[PATCH v5 1/3] dt-bindings: media: atmel: csi2dc: add bindings for microchip csi2dc

[PATCH v5 1/3] dt-bindings: media: atmel: csi2dc: add bindings for microchip csi2dc

[Eugen Hristev]

Add bindings documentation for Microchip CSI2 Demultiplexer controller.

CSI2DC is a demultiplexer from Synopsys IDI interface specification to
parallel interface connection or direct memory access.

Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
---
Changes in v5:
- modified bindings as per Rob Herring review

Changes in v4:
- Removed property for inter-line-delay and for clock continuous/non-continuous
- Removed virtual channel by reg for second endpoint

Changes in v3:
- Removed some text from description, as it was explained in the schema
- fixed other things as per Rob's review
- moved some text inside the schema, like the clock description

Changes in v2:
- fixed warnings reported by dt_binding_check

 .../bindings/media/microchip,csi2dc.yaml      | 119 ++++++++++++++++++
 1 file changed, 119 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/media/microchip,csi2dc.yaml

diff --git a/Documentation/devicetree/bindings/media/microchip,csi2dc.yaml b/Documentation/devicetree/bindings/media/microchip,csi2dc.yaml
new file mode 100644
index 000000000000..e79f0d6ba9db
--- /dev/null
+++ b/Documentation/devicetree/bindings/media/microchip,csi2dc.yaml
@@ -0,0 +1,119 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/media/microchip,csi2dc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Microchip CSI2 Demux Controller (CSI2DC)
+
+maintainers:
+  - Eugen Hristev <eugen.hristev@microchip.com>
+
+description:
+  CSI2DC - Camera Serial Interface 2 Demux Controller
+
+  CSI2DC is a hardware block that receives incoming data from an IDI interface
+  and filters packets based on their data type and virtual channel identifier,
+  then converts the byte stream into a cross clock domain to a pixel stream
+  to a parallel interface that can be read by a sensor controller.
+
+  CSI2DC provides two pipes, one video pipe and one data pipe. Video pipe
+  is connected to a sensor controller and the data pipe is accessible
+  as a DMA slave port to a DMA controller.
+
+  CSI2DC supports a single 'port' node as a source pad with Synopsys 32-bit
+  IDI interface. The connected endpoint must be a IDI interface compatible
+  device (like Synopsys CSI2HOST) , that can provide 32-bit IDI interface
+  connection as sink pad.
+  For media entity and endpoints please refer to the bindings defined in
+  Documentation/devicetree/bindings/media/video-interfaces.txt.
+  For Synopsys IDI interface please refer to
+  Documentation/devicetree/bindings/media/snps,dw-csi-plat.txt
+
+  CSI2DC supports one 'port' node as sink pad with parallel interface. This is
+  called video pipe.
+  This port has an 'endpoint' can then be used as a source pad for another
+  controller (next in pipeline).
+  Please refer to the bindings defined in
+  Documentation/devicetree/bindings/media/video-interfaces.txt.
+
+  CSI2DC also supports direct access to the data through AHB, via DMA channel,
+  called data pipe.
+  Because of this, the sink 'port' child node (second) is not mandatory.
+  If the sink 'port' child node is missing, only data pipe is available.
+
+properties:
+  compatible:
+    const: microchip,sama7g5-csi2dc
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    maxItems: 2
+
+  clock-names:
+    description:
+      CSI2DC must have two clocks to function correctly. One clock is the
+      peripheral clock for the inside functionality of the hardware block.
+      This is named 'pclk'. The second clock must be the cross domain clock,
+      in which CSI2DC will perform clock crossing. This clock must be fed
+      by the next controller in pipeline, which usually is a sensor controller.
+      Normally this clock should be given by this sensor controller who
+      is also a clock source. This clock is named 'scck', sensor controller clock.
+    items:
+      - const: pclk
+      - const: scck
+
+  ports:
+    type: object
+    description:
+      List of ports
+
+    properties:
+      port@0:
+        type: object
+        description:
+          Input port node, single endpoint describing the input pad.
+      port@1:
+        type: object
+        description:
+          Output port node, single endpoint, describing the output pad.
+
+additionalProperties: false
+
+required:
+  - compatible
+  - reg
+  - clocks
+  - clock-names
+  - ports
+
+examples:
+  - |
+    csi2dc@e1404000 {
+        compatible = "microchip,sama7g5-csi2dc";
+        reg = <0xe1404000 0x500>;
+        clocks = <&pclk>, <&scck>;
+        clock-names = "pclk", "scck";
+
+        ports {
+               #address-cells = <1>;
+               #size-cells = <0>;
+               port@0 {
+                       reg = <0>; /* must be 0, first child port */
+                       csi2dc_in: endpoint { /* input from IDI interface */
+                               remote-endpoint = <&csi2host_out>;
+                       };
+               };
+
+               port@1 {
+                       reg = <1>; /* must be 1, second child port */
+                       csi2dc_out: endpoint {
+                               remote-endpoint = <&xisc_in>; /* output to sensor controller */
+                       };
+               };
+        };
+    };
+
+...
-- 
2.25.1

[PATCH v5 2/3] media: atmel: introduce microchip csi2dc driver

[Eugen Hristev]

Microchip CSI2DC (CSI2 Demultiplexer Controller) is a misc bridge device
that converts a byte stream in IDI Synopsys format (coming from a CSI2HOST)
to a pixel stream that can be captured by a sensor controller.

Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
---
Hello,

There still are some open questions regarding the last reviews on the ML.

Regarding the format list which is not const, I cannot have it const because
I reference elements from this list into a dynamic list which is non-const.

Regarding the presence of the v4l2_dev, without this I cannot add a notifier
for this device to have it async completed , when the underlying subdevice
finishes probing.

Regarding the callbacks for set frame interval, set frame size, etc, I cannot
remove them because losing functionality to the underlying subdevice, as
explained in :
https://lkml.org/lkml/2020/10/12/427

Changes in v5:
- only in bindings

Changes in v4:
- now using get_mbus_config ops to get data from the subdevice, like the
virtual channel id, and the clock type.
- now having possibility to select any of the RAW10 data modes
- at completion time, select which formats are also available in the subdevice,
and move to the dynamic list accordingly
- changed the pipeline integration, do not advertise subdev ready at probe time.
wait until completion is done, and then start a workqueue that will register
this device as a subdevice for the next element in pipeline.
- moved the s_power code into a different function called now csi2dc_power
that is called with CONFIG_PM functions. This is also called at completion,
to have the device ready in case CONFIG_PM is not selected on the platform.
- merged try_fmt into set_fmt
- driver cleanup, wrapped lines over 80 characters

Changes in v2:
- moved driver to platform/atmel
- fixed minor things as per Sakari's review
- still some things from v2 review are not yet addressed, to be followed up

 drivers/media/platform/atmel/Kconfig          |  13 +
 drivers/media/platform/atmel/Makefile         |   1 +
 .../media/platform/atmel/microchip-csi2dc.c   | 785 ++++++++++++++++++
 3 files changed, 799 insertions(+)
 create mode 100644 drivers/media/platform/atmel/microchip-csi2dc.c

diff --git a/drivers/media/platform/atmel/Kconfig b/drivers/media/platform/atmel/Kconfig
index 99b51213f871..147e1c14129b 100644
--- a/drivers/media/platform/atmel/Kconfig
+++ b/drivers/media/platform/atmel/Kconfig
@@ -32,3 +32,16 @@ config VIDEO_ATMEL_ISI
 	help
 	  This module makes the ATMEL Image Sensor Interface available
 	  as a v4l2 device.
+
+config VIDEO_MICROCHIP_CSI2DC
+	tristate "Microchip CSI2 Demux Controller"
+	depends on VIDEO_V4L2 && COMMON_CLK && OF
+	depends on ARCH_AT91 || COMPILE_TEST
+	select MEDIA_CONTROLLER
+	select VIDEO_V4L2_SUBDEV_API
+	select V4L2_FWNODE
+	help
+	  CSI2 Demux Controller driver. CSI2DC is a helper chip
+	  that converts IDI interface byte stream to a parallel pixel stream.
+	  It supports various RAW formats as input.
+	  Performs clock domain crossing between hardware blocks.
diff --git a/drivers/media/platform/atmel/Makefile b/drivers/media/platform/atmel/Makefile
index c5c01556c653..8e80af500bf5 100644
--- a/drivers/media/platform/atmel/Makefile
+++ b/drivers/media/platform/atmel/Makefile
@@ -5,3 +5,4 @@ atmel-xisc-objs = atmel-sama7g5-isc.o atmel-isc-base.o
 obj-$(CONFIG_VIDEO_ATMEL_ISI) += atmel-isi.o
 obj-$(CONFIG_VIDEO_ATMEL_ISC) += atmel-isc.o
 obj-$(CONFIG_VIDEO_ATMEL_XISC) += atmel-xisc.o
+obj-$(CONFIG_VIDEO_MICROCHIP_CSI2DC) += microchip-csi2dc.o
diff --git a/drivers/media/platform/atmel/microchip-csi2dc.c b/drivers/media/platform/atmel/microchip-csi2dc.c
new file mode 100644
index 000000000000..fda1d5882dbb
--- /dev/null
+++ b/drivers/media/platform/atmel/microchip-csi2dc.c
@@ -0,0 +1,785 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Microchip CSI2 Demux Controller (CSI2DC) driver
+ *
+ * Copyright (C) 2018-2020 Microchip Technology, Inc.
+ *
+ * Author: Eugen Hristev <eugen.hristev@microchip.com>
+ *
+ */
+
+#include <linux/clk.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_graph.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/videodev2.h>
+
+#include <media/v4l2-device.h>
+#include <media/v4l2-fwnode.h>
+#include <media/v4l2-subdev.h>
+#include <media/videobuf2-dma-contig.h>
+
+/* Global configuration register */
+#define CSI2DC_GCFG			0x0
+
+/* MIPI sensor pixel clock is free running */
+#define CSI2DC_GCFG_MIPIFRN		BIT(0)
+/* Output waveform inter-line minimum delay */
+#define CSI2DC_GCFG_HLC(v)		((v) << 4)
+#define CSI2DC_GCFG_HLC_MASK		GENMASK(7, 4)
+/* SAMA7G5 requires a HLC delay of 15 */
+#define SAMA7G5_HLC			(15)
+
+/* Global control register */
+#define CSI2DC_GCTLR			0x04
+#define CSI2DC_GCTLR_SWRST		BIT(0)
+
+/* Global status register */
+#define CSI2DC_GS			0x08
+
+/* SSP interrupt status register */
+#define CSI2DC_SSPIS			0x28
+/* Pipe update register */
+#define CSI2DC_PU			0xC0
+/* Video pipe attributes update */
+#define CSI2DC_PU_VP			BIT(0)
+
+/* Pipe update status register */
+#define CSI2DC_PUS			0xC4
+
+/* Video pipeline enable register */
+#define CSI2DC_VPE			0xF8
+#define CSI2DC_VPE_ENABLE		BIT(0)
+
+/* Video pipeline configuration register */
+#define CSI2DC_VPCFG			0xFC
+/* Data type */
+#define CSI2DC_VPCFG_DT(v)		((v) << 0)
+#define CSI2DC_VPCFG_DT_MASK		GENMASK(5, 0)
+/* Virtual channel identifier */
+#define CSI2DC_VPCFG_VC(v)		((v) << 6)
+#define CSI2DC_VPCFG_VC_MASK		GENMASK(7, 6)
+/* Decompression enable */
+#define CSI2DC_VPCFG_DE			BIT(8)
+/* Decoder mode */
+#define CSI2DC_VPCFG_DM(v)		((v) << 9)
+#define CSI2DC_VPCFG_DM_DECODER8TO12	0
+/* Decoder predictor 2 selection */
+#define CSI2DC_VPCFG_DP2		BIT(12)
+/* Recommended memory storage */
+#define CSI2DC_VPCFG_RMS		BIT(13)
+/* Post adjustment */
+#define CSI2DC_VPCFG_PA			BIT(14)
+
+/* Video pipeline column register */
+#define CSI2DC_VPCOL			0x100
+/* Column number */
+#define CSI2DC_VPCOL_COL(v)		((v) << 0)
+#define CSI2DC_VPCOL_COL_MASK		GENMASK(15, 0)
+
+/* Video pipeline row register */
+#define CSI2DC_VPROW			0x104
+/* Row number */
+#define CSI2DC_VPROW_ROW(v)		((v) << 0)
+#define CSI2DC_VPROW_ROW_MASK		GENMASK(15, 0)
+
+/* Version register */
+#define CSI2DC_VERSION			0x1FC
+
+/* register read/write helpers */
+#define csi2dc_readl(st, reg)		readl_relaxed((st)->base + (reg))
+#define csi2dc_writel(st, reg, val)	writel_relaxed((val), \
+					(st)->base + (reg))
+
+/* supported RAW data types */
+#define CSI2DC_DT_RAW6			0x28
+#define CSI2DC_DT_RAW7			0x29
+#define CSI2DC_DT_RAW8			0x2A
+#define CSI2DC_DT_RAW10			0x2B
+#define CSI2DC_DT_RAW12			0x2C
+#define CSI2DC_DT_RAW14			0x2D
+
+struct csi2dc_format {
+	u32				mbus_code;
+	u32				dt;
+};
+
+static struct csi2dc_format csi2dc_formats_list[] = {
+	{
+		.mbus_code =		MEDIA_BUS_FMT_SRGGB10_1X10,
+		.dt =			CSI2DC_DT_RAW10,
+	}, {
+		.mbus_code =		MEDIA_BUS_FMT_SBGGR10_1X10,
+		.dt =			CSI2DC_DT_RAW10,
+	}, {
+		.mbus_code =		MEDIA_BUS_FMT_SGRBG10_1X10,
+		.dt =			CSI2DC_DT_RAW10,
+	}, {
+		.mbus_code =		MEDIA_BUS_FMT_SGBRG10_1X10,
+		.dt =			CSI2DC_DT_RAW10,
+	},
+};
+
+enum mipi_csi_pads {
+	CSI2DC_PAD_SINK			= 0,
+	CSI2DC_PAD_SOURCE		= 1,
+	CSI2DC_PADS_NUM			= 2,
+};
+
+struct csi2dc_device {
+	void __iomem			*base;
+	struct v4l2_subdev		csi2dc_sd;
+	struct device			*dev;
+	struct v4l2_device		v4l2_dev;
+	struct clk			*pclk;
+	struct clk			*scck;
+
+	bool				video_pipe;
+
+	u32				num_fmts;
+	struct csi2dc_format		**formats;
+
+	struct csi2dc_format		*cur_fmt;
+	struct csi2dc_format		*try_fmt;
+
+	struct media_pad		pads[CSI2DC_PADS_NUM];
+
+	bool				clk_gated;
+	u32				vc;
+
+	struct v4l2_async_subdev	*asd;
+	struct v4l2_async_notifier	notifier;
+
+	struct v4l2_subdev		*input_sd;
+
+	u32				remote_pad;
+
+	bool				completed;
+	bool				powered_on;
+
+	struct work_struct		workq;
+};
+
+static void csi2dc_vp_update(struct csi2dc_device *csi2dc)
+{
+	u32 vp;
+
+	vp = CSI2DC_VPCFG_DT(csi2dc->cur_fmt->dt) & CSI2DC_VPCFG_DT_MASK;
+	vp |= CSI2DC_VPCFG_VC(csi2dc->vc) & CSI2DC_VPCFG_VC_MASK;
+	vp &= ~CSI2DC_VPCFG_DE;
+	vp |= CSI2DC_VPCFG_DM(CSI2DC_VPCFG_DM_DECODER8TO12);
+	vp &= ~CSI2DC_VPCFG_DP2;
+	vp &= ~CSI2DC_VPCFG_RMS;
+	vp |= CSI2DC_VPCFG_PA;
+
+	csi2dc_writel(csi2dc, CSI2DC_VPCFG, vp);
+	csi2dc_writel(csi2dc, CSI2DC_VPE, CSI2DC_VPE_ENABLE);
+	csi2dc_writel(csi2dc, CSI2DC_PU, CSI2DC_PU_VP);
+}
+
+static inline struct csi2dc_device *
+csi2dc_sd_to_csi2dc_device(struct v4l2_subdev *csi2dc_sd)
+{
+	return container_of(csi2dc_sd, struct csi2dc_device, csi2dc_sd);
+}
+
+static int csi2dc_enum_mbus_code(struct v4l2_subdev *csi2dc_sd,
+				 struct v4l2_subdev_pad_config *cfg,
+				 struct v4l2_subdev_mbus_code_enum *code)
+{
+	struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
+
+	if (code->index >= csi2dc->num_fmts)
+		return -EINVAL;
+
+	code->code = csi2dc->formats[code->index]->mbus_code;
+	return 0;
+}
+
+static int csi2dc_set_fmt(struct v4l2_subdev *csi2dc_sd,
+			  struct v4l2_subdev_pad_config *cfg,
+			  struct v4l2_subdev_format *req_fmt)
+{
+	struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
+	struct csi2dc_format *fmt;
+	int ret, i;
+
+	if (!csi2dc->completed) {
+		dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
+		return 0;
+	}
+
+	for (fmt = csi2dc->formats[0], i = 0; i < csi2dc->num_fmts; fmt++, i++)
+		if (req_fmt->format.code == fmt->mbus_code)
+			csi2dc->try_fmt = fmt;
+
+	/* in case we could not find the desired format, default to something */
+	if (!csi2dc->try_fmt  ||
+	    req_fmt->format.code != csi2dc->try_fmt->mbus_code) {
+		csi2dc->try_fmt = csi2dc->formats[0];
+
+		dev_dbg(csi2dc->dev,
+			"CSI2DC unsupported format 0x%x, defaulting to 0x%x\n",
+			req_fmt->format.code, csi2dc->formats[0]->mbus_code);
+
+		req_fmt->format.code = csi2dc->formats[0]->mbus_code;
+	}
+
+	/* if we are just trying, we are done */
+	if (req_fmt->which == V4L2_SUBDEV_FORMAT_TRY)
+		return 0;
+
+	ret = v4l2_subdev_call(csi2dc->input_sd, pad, set_fmt, cfg, req_fmt);
+	if (ret) {
+		dev_err(csi2dc->dev, "input subdev failed %d\n", ret);
+		return ret;
+	}
+
+	csi2dc->cur_fmt = csi2dc->try_fmt;
+	/* update video pipe */
+	csi2dc_vp_update(csi2dc);
+
+	dev_dbg(csi2dc->dev, "CSI2DC new format: 0x%x\n", req_fmt->format.code);
+	return 0;
+}
+
+static int csi2dc_formats_init(struct csi2dc_device *csi2dc)
+{
+	struct csi2dc_format *fmt;
+	struct v4l2_subdev *subdev = csi2dc->input_sd;
+	unsigned int num_fmts, i;
+
+	struct v4l2_subdev_mbus_code_enum mbus_code = {
+		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+		.index = 0,
+	};
+
+	num_fmts = 0;
+
+	csi2dc->formats = devm_kcalloc(csi2dc->dev,
+				       ARRAY_SIZE(csi2dc_formats_list),
+				       sizeof(*csi2dc->formats), GFP_KERNEL);
+	if (!csi2dc->formats)
+		return -ENOMEM;
+
+	while (!v4l2_subdev_call(subdev, pad, enum_mbus_code, NULL,
+	       &mbus_code)) {
+		mbus_code.index++;
+		for (fmt = &csi2dc_formats_list[0], i = 0;
+		     i < ARRAY_SIZE(csi2dc_formats_list); i++, fmt++)
+			if (fmt->mbus_code == mbus_code.code) {
+				csi2dc->formats[num_fmts] = fmt;
+				num_fmts++;
+			}
+	}
+
+	if (!num_fmts)
+		return -ENXIO;
+
+	csi2dc->num_fmts = num_fmts;
+
+	return 0;
+}
+
+static int csi2dc_power(struct csi2dc_device *csi2dc, int on)
+{
+	int ret = 0;
+
+	if (!csi2dc->completed) {
+		dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
+		return 0;
+	}
+
+	if (csi2dc->powered_on == on)
+		return 0;
+
+	if (on)
+		ret = clk_prepare_enable(csi2dc->scck);
+	else
+		clk_disable_unprepare(csi2dc->scck);
+	if (ret)
+		dev_err(csi2dc->dev, "failed to enable scck: %d\n", ret);
+
+	/* if powering up, deassert reset line */
+	if (on)
+		csi2dc_writel(csi2dc, CSI2DC_GCTLR, CSI2DC_GCTLR_SWRST);
+
+	/* if powering down, assert reset line */
+	if (!on)
+		csi2dc_writel(csi2dc, CSI2DC_GCTLR, !CSI2DC_GCTLR_SWRST);
+	if (!ret)
+		csi2dc->powered_on = on;
+
+	return ret;
+}
+
+static int csi2dc_s_stream(struct v4l2_subdev *csi2dc_sd, int enable)
+{
+	struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
+
+	if (!csi2dc->completed) {
+		dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
+		return 0;
+	}
+
+	return v4l2_subdev_call(csi2dc->input_sd, video, s_stream, enable);
+}
+
+static int csi2dc_g_frame_interval(struct v4l2_subdev *csi2dc_sd,
+				   struct v4l2_subdev_frame_interval *interval)
+{
+	struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
+
+	if (!csi2dc->completed) {
+		dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
+		return 0;
+	}
+
+	return v4l2_subdev_call(csi2dc->input_sd, video, g_frame_interval,
+				interval);
+}
+
+static int csi2dc_s_frame_interval(struct v4l2_subdev *csi2dc_sd,
+				   struct v4l2_subdev_frame_interval *interval)
+{
+	struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
+
+	if (!csi2dc->completed) {
+		dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
+		return 0;
+	}
+
+	return v4l2_subdev_call(csi2dc->input_sd, video, s_frame_interval,
+				interval);
+}
+
+static int csi2dc_enum_frame_size(struct v4l2_subdev *csi2dc_sd,
+				  struct v4l2_subdev_pad_config *cfg,
+				  struct v4l2_subdev_frame_size_enum *fse)
+{
+	struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
+
+	if (!csi2dc->completed) {
+		dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
+		return 0;
+	}
+
+	return v4l2_subdev_call(csi2dc->input_sd, pad, enum_frame_size, cfg,
+				fse);
+}
+
+static int csi2dc_enum_frame_interval(struct v4l2_subdev *csi2dc_sd,
+			      struct v4l2_subdev_pad_config *cfg,
+			      struct v4l2_subdev_frame_interval_enum *fie)
+{
+	struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
+
+	if (!csi2dc->completed) {
+		dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
+		return 0;
+	}
+
+	return v4l2_subdev_call(csi2dc->input_sd, pad, enum_frame_interval, cfg,
+				fie);
+}
+
+static const struct v4l2_subdev_pad_ops csi2dc_pad_ops = {
+	.enum_mbus_code = csi2dc_enum_mbus_code,
+	.set_fmt = csi2dc_set_fmt,
+	.enum_frame_size = csi2dc_enum_frame_size,
+	.enum_frame_interval = csi2dc_enum_frame_interval,
+};
+
+static const struct v4l2_subdev_video_ops csi2dc_video_ops = {
+	.s_stream = csi2dc_s_stream,
+	.g_frame_interval = csi2dc_g_frame_interval,
+	.s_frame_interval = csi2dc_s_frame_interval,
+};
+
+static const struct v4l2_subdev_ops csi2dc_subdev_ops = {
+	.pad = &csi2dc_pad_ops,
+	.video = &csi2dc_video_ops,
+};
+
+static int csi2dc_get_mbus_config(struct csi2dc_device *csi2dc)
+{
+	struct v4l2_mbus_config mbus_config = { 0 };
+	int ret;
+
+	ret = v4l2_subdev_call(csi2dc->input_sd, pad, get_mbus_config,
+			       csi2dc->remote_pad, &mbus_config);
+	if (ret == -ENOIOCTLCMD) {
+		dev_dbg(csi2dc->dev,
+			"no remote mbus configuration available\n");
+		goto csi2dc_get_mbus_config_defaults;
+	}
+
+	if (ret) {
+		dev_err(csi2dc->dev,
+			"failed to get remote mbus configuration\n");
+		goto csi2dc_get_mbus_config_defaults;
+	}
+
+	if (mbus_config.flags & V4L2_MBUS_CSI2_CHANNEL_0)
+		csi2dc->vc = 0;
+	else if (mbus_config.flags & V4L2_MBUS_CSI2_CHANNEL_1)
+		csi2dc->vc = 1;
+	else if (mbus_config.flags & V4L2_MBUS_CSI2_CHANNEL_2)
+		csi2dc->vc = 2;
+	else if (mbus_config.flags & V4L2_MBUS_CSI2_CHANNEL_3)
+		csi2dc->vc = 3;
+
+	dev_dbg(csi2dc->dev, "subdev sending on channel %d\n", csi2dc->vc);
+
+	csi2dc->clk_gated = mbus_config.flags &
+			    V4L2_MBUS_CSI2_NONCONTINUOUS_CLOCK;
+
+	dev_dbg(csi2dc->dev, "%s clock\n",
+		csi2dc->clk_gated ? "gated" : "free running");
+
+	return 0;
+
+csi2dc_get_mbus_config_defaults:
+	csi2dc->vc = 0; /* Virtual ID 0 by default */
+	csi2dc->clk_gated = false; /* Free running clock by default */
+
+	return 0;
+}
+
+static int csi2dc_async_bound(struct v4l2_async_notifier *notifier,
+			      struct v4l2_subdev *subdev,
+			      struct v4l2_async_subdev *asd)
+{
+	struct csi2dc_device *csi2dc = container_of(notifier->v4l2_dev,
+					struct csi2dc_device, v4l2_dev);
+	int pad;
+
+	csi2dc->input_sd = subdev;
+
+	pad = media_entity_get_fwnode_pad(&subdev->entity,
+					  asd->match.fwnode,
+					  MEDIA_PAD_FL_SOURCE);
+	if (pad < 0) {
+		dev_err(csi2dc->dev, "Failed to find pad for %s\n",
+			subdev->name);
+		return pad;
+	}
+
+	csi2dc->remote_pad = pad;
+
+	csi2dc_get_mbus_config(csi2dc);
+
+	return 0;
+}
+
+static int csi2dc_async_complete(struct v4l2_async_notifier *notifier)
+{
+	struct csi2dc_device *csi2dc =
+		container_of(notifier->v4l2_dev, struct csi2dc_device,
+			     v4l2_dev);
+	int ret;
+
+	ret = csi2dc_formats_init(csi2dc);
+	if (ret)
+		return ret;
+
+	ret = v4l2_device_register_subdev_nodes(&csi2dc->v4l2_dev);
+	if (ret < 0) {
+		v4l2_err(&csi2dc->v4l2_dev,
+			 "failed to register subdev nodes\n");
+		return ret;
+	}
+
+	csi2dc->completed = true;
+
+	csi2dc_writel(csi2dc, CSI2DC_GCFG,
+		      (SAMA7G5_HLC & CSI2DC_GCFG_HLC_MASK) |
+		      (csi2dc->clk_gated ? 0 : CSI2DC_GCFG_MIPIFRN));
+
+	csi2dc_writel(csi2dc, CSI2DC_VPCOL,
+		      CSI2DC_VPCOL_COL(0xFFF) & CSI2DC_VPCOL_COL_MASK);
+	csi2dc_writel(csi2dc, CSI2DC_VPROW,
+		      CSI2DC_VPROW_ROW(0xFFF) & CSI2DC_VPROW_ROW_MASK);
+
+	/* once we are completed, we can register ourselves in the pipeline */
+	schedule_work(&csi2dc->workq);
+
+	return ret;
+}
+
+static const struct v4l2_async_notifier_operations csi2dc_async_ops = {
+	.bound = csi2dc_async_bound,
+	.complete = csi2dc_async_complete,
+};
+
+static void csi2dc_cleanup_notifier(struct csi2dc_device *csi2dc)
+{
+	v4l2_async_notifier_unregister(&csi2dc->notifier);
+	v4l2_async_notifier_cleanup(&csi2dc->notifier);
+}
+
+static int csi2dc_prepare_notifier(struct csi2dc_device *csi2dc,
+				   struct device_node *input_parent)
+{
+	int ret;
+
+	v4l2_async_notifier_init(&csi2dc->notifier);
+
+	csi2dc->asd = kzalloc(sizeof(*csi2dc->asd), GFP_KERNEL);
+	if (!csi2dc->asd)
+		return -ENOMEM;
+
+	csi2dc->asd->match_type = V4L2_ASYNC_MATCH_FWNODE;
+	csi2dc->asd->match.fwnode = of_fwnode_handle(input_parent);
+
+	ret = v4l2_async_notifier_add_subdev(&csi2dc->notifier, csi2dc->asd);
+	if (ret) {
+		dev_err(csi2dc->dev, "failed to add async notifier.\n");
+		v4l2_async_notifier_cleanup(&csi2dc->notifier);
+		goto csi2dc_prepare_notifier_err;
+	}
+
+	csi2dc->notifier.ops = &csi2dc_async_ops;
+
+	ret = v4l2_async_notifier_register(&csi2dc->v4l2_dev,
+					   &csi2dc->notifier);
+
+	if (ret) {
+		dev_err(csi2dc->dev, "fail to register async notifier.\n");
+		goto csi2dc_prepare_notifier_err;
+	}
+
+csi2dc_prepare_notifier_err:
+	of_node_put(input_parent);
+
+	return ret;
+}
+
+static int csi2dc_of_parse(struct csi2dc_device *csi2dc,
+			   struct device_node *of_node)
+{
+	struct device_node *input_node, *sink_node, *input_parent;
+	struct v4l2_fwnode_endpoint input_endpoint = { 0 },
+				    sink_endpoint = { 0 };
+	int ret;
+
+	input_node = of_graph_get_next_endpoint(of_node, NULL);
+
+	if (!input_node) {
+		dev_err(csi2dc->dev,
+			"missing port node at %s, input node is mandatory.\n",
+			of_node->full_name);
+		return -EINVAL;
+	}
+
+	ret = v4l2_fwnode_endpoint_parse(of_fwnode_handle(input_node),
+					 &input_endpoint);
+
+	if (ret) {
+		dev_err(csi2dc->dev, "endpoint not defined at %s\n",
+			of_node->full_name);
+		return ret;
+	}
+
+	input_parent = of_graph_get_remote_port_parent(input_node);
+	if (!input_parent) {
+		dev_err(csi2dc->dev,
+			"could not get input node's parent node.\n");
+		return -EINVAL;
+	}
+
+	sink_node = of_graph_get_next_endpoint(of_node, input_node);
+
+	if (sink_node)
+		ret = v4l2_fwnode_endpoint_parse(of_fwnode_handle(sink_node),
+						 &sink_endpoint);
+
+	if (!sink_node || ret) {
+		dev_info(csi2dc->dev,
+			 "missing sink node at %s, data pipe available only.\n",
+			 of_node->full_name);
+	} else {
+		csi2dc->video_pipe = true;
+
+		dev_dbg(csi2dc->dev, "block %s %d.%d->%d.%d video pipeline\n",
+			of_node->full_name, input_endpoint.base.port,
+			input_endpoint.base.id,	sink_endpoint.base.port,
+			sink_endpoint.base.id);
+	}
+
+	of_node_put(sink_node);
+	of_node_put(input_node);
+
+	/* prepare async notifier for subdevice completion */
+	return csi2dc_prepare_notifier(csi2dc, input_parent);
+}
+
+static void csi2dc_workq_handler(struct work_struct *workq)
+{
+	struct csi2dc_device *csi2dc = container_of(workq,
+					struct csi2dc_device, workq);
+	int ret;
+
+	if (v4l2_async_register_subdev(&csi2dc->csi2dc_sd))
+		dev_dbg(csi2dc->dev, "failed to register the subdevice\n");
+
+	ret = csi2dc_power(csi2dc, true);
+	if (ret < 0)
+		v4l2_err(&csi2dc->v4l2_dev, "failed to power on\n");
+}
+
+static int csi2dc_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct csi2dc_device *csi2dc;
+	struct resource *res = NULL;
+	int ret = 0;
+
+	csi2dc = devm_kzalloc(dev, sizeof(*csi2dc), GFP_KERNEL);
+	if (!csi2dc)
+		return -ENOMEM;
+
+	csi2dc->dev = dev;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -EINVAL;
+
+	csi2dc->base = devm_ioremap_resource(dev, res);
+
+	if (IS_ERR(csi2dc->base)) {
+		dev_err(dev, "base address not set\n");
+		return PTR_ERR(csi2dc->base);
+	}
+
+	csi2dc->pclk = devm_clk_get(dev, "pclk");
+	if (IS_ERR(csi2dc->pclk)) {
+		ret = PTR_ERR(csi2dc->pclk);
+		dev_err(dev, "failed to get pclk: %d\n", ret);
+		return ret;
+	}
+
+	ret = clk_prepare_enable(csi2dc->pclk);
+	if (ret) {
+		dev_err(dev, "failed to enable pclk: %d\n", ret);
+		return ret;
+	}
+
+	csi2dc->scck = devm_clk_get(dev, "scck");
+	if (IS_ERR(csi2dc->scck)) {
+		ret = PTR_ERR(csi2dc->scck);
+		dev_err(dev, "failed to get scck: %d\n", ret);
+		goto csi2dc_clk_fail;
+	}
+
+	ret = v4l2_device_register(dev, &csi2dc->v4l2_dev);
+	if (ret) {
+		dev_err(dev, "unable to register v4l2 device.\n");
+		goto csi2dc_clk_fail;
+	}
+
+	v4l2_subdev_init(&csi2dc->csi2dc_sd, &csi2dc_subdev_ops);
+
+	csi2dc->csi2dc_sd.owner = THIS_MODULE;
+	csi2dc->csi2dc_sd.dev = dev;
+	snprintf(csi2dc->csi2dc_sd.name, sizeof(csi2dc->csi2dc_sd.name),
+		 "CSI2DC.0");
+
+	csi2dc->csi2dc_sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
+	csi2dc->csi2dc_sd.entity.function = MEDIA_ENT_F_VID_IF_BRIDGE;
+	csi2dc->pads[CSI2DC_PAD_SINK].flags = MEDIA_PAD_FL_SINK;
+	csi2dc->pads[CSI2DC_PAD_SOURCE].flags = MEDIA_PAD_FL_SOURCE;
+
+	ret = media_entity_pads_init(&csi2dc->csi2dc_sd.entity, CSI2DC_PADS_NUM,
+				     csi2dc->pads);
+	if (ret < 0) {
+		dev_err(dev, "media entity init failed\n");
+		goto csi2dc_probe_entity_err;
+	}
+
+	v4l2_set_subdevdata(&csi2dc->csi2dc_sd, pdev);
+
+	platform_set_drvdata(pdev, &csi2dc->csi2dc_sd);
+
+	INIT_WORK(&csi2dc->workq, csi2dc_workq_handler);
+
+	ret = csi2dc_of_parse(csi2dc, dev->of_node);
+	if (ret)
+		goto csi2dc_probe_entity_err;
+
+	dev_info(dev, "Microchip CSI2DC version %x\n",
+		 csi2dc_readl(csi2dc, CSI2DC_VERSION));
+
+	pm_runtime_set_active(dev);
+	pm_runtime_enable(dev);
+	pm_request_idle(dev);
+
+	return 0;
+
+csi2dc_probe_entity_err:
+	media_entity_cleanup(&csi2dc->csi2dc_sd.entity);
+	v4l2_device_unregister(&csi2dc->v4l2_dev);
+csi2dc_clk_fail:
+	clk_disable_unprepare(csi2dc->pclk);
+	return ret;
+}
+
+static int csi2dc_remove(struct platform_device *pdev)
+{
+	struct v4l2_subdev *csi2dc_sd = platform_get_drvdata(pdev);
+	struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
+
+	pm_runtime_disable(&pdev->dev);
+
+	v4l2_async_unregister_subdev(&csi2dc->csi2dc_sd);
+	csi2dc_cleanup_notifier(csi2dc);
+	media_entity_cleanup(&csi2dc->csi2dc_sd.entity);
+	v4l2_device_unregister(&csi2dc->v4l2_dev);
+	clk_disable_unprepare(csi2dc->pclk);
+
+	return 0;
+}
+
+static int __maybe_unused csi2dc_runtime_suspend(struct device *dev)
+{
+	struct csi2dc_device *csi2dc = dev_get_drvdata(dev);
+
+	return csi2dc_power(csi2dc, false);
+}
+
+static int __maybe_unused csi2dc_runtime_resume(struct device *dev)
+{
+	struct csi2dc_device *csi2dc = dev_get_drvdata(dev);
+
+	return csi2dc_power(csi2dc, true);
+}
+
+static const struct dev_pm_ops csi2dc_dev_pm_ops = {
+	SET_RUNTIME_PM_OPS(csi2dc_runtime_suspend, csi2dc_runtime_resume, NULL)
+};
+
+static const struct of_device_id csi2dc_of_match[] = {
+	{ .compatible = "microchip,sama7g5-csi2dc" },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(of, csi2dc_of_match);
+
+static struct platform_driver csi2dc_driver = {
+	.probe	= csi2dc_probe,
+	.remove	= csi2dc_remove,
+	.driver	= {
+		.name		= "microchip-csi2dc",
+		.pm		= &csi2dc_dev_pm_ops,
+		.of_match_table = of_match_ptr(csi2dc_of_match),
+	},
+};
+
+module_platform_driver(csi2dc_driver);
+
+MODULE_AUTHOR("Eugen Hristev <eugen.hristev@microchip.com>");
+MODULE_DESCRIPTION("Microchip CSI2 Demux Controller driver");
+MODULE_LICENSE("GPL v2");
+MODULE_SUPPORTED_DEVICE("video");
-- 
2.25.1

Re: [PATCH v5 2/3] media: atmel: introduce microchip csi2dc driver

[Jacopo Mondi]

Hi Eugen,

On Thu, Nov 12, 2020 at 03:34:36PM +0200, Eugen Hristev wrote:
> Microchip CSI2DC (CSI2 Demultiplexer Controller) is a misc bridge device
> that converts a byte stream in IDI Synopsys format (coming from a CSI2HOST)
> to a pixel stream that can be captured by a sensor controller.
>
> Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
> ---
> Hello,
>
> There still are some open questions regarding the last reviews on the ML.
>
> Regarding the format list which is not const, I cannot have it const because
> I reference elements from this list into a dynamic list which is non-const.
>
> Regarding the presence of the v4l2_dev, without this I cannot add a notifier
> for this device to have it async completed , when the underlying subdevice
> finishes probing.
>

I see you have a discussion with Sakari on-going on this, and I have
the very same comment he had.

Should a sub-notifier be used and this driver should not register any
v4l2_dev but integrate in the media graph of the receiver ?

For reference, rcar-csi2 uses sub-notifiers and register in the
rcar-vin media graph, it doesn't need to set up a v4l2_dev.

rcar-vin (the DMA engine driver) that register video nodes and the v4l2-dev
also registers the device nodes for all the connected subdevices.

> Regarding the callbacks for set frame interval, set frame size, etc, I cannot
> remove them because losing functionality to the underlying subdevice, as
> explained in :
> https://lkml.org/lkml/2020/10/12/427
>

Using the frame sizes as in the example you reported, if this device has
limitations on the supported sizes, (a min and a max most
probably) that's the only thing that should be exposed from this
driver subdevice. The sensor subdevice instead will report the
available discrete sizes and userspace configures the sensor's source
pad and the bridge's sink pad with the same sizes to properly set up the
capture pipeline. video0 should not report the sizes exposed by the sensor
nor any information that depends on what's connected to it.

I know what your next question is: what about existing application
that only know about video0 and want to setup everything from there. I
understand vendors not wanting to wrap gstreamer or what is used in
the wild in custom scripts that sets up the pipeline opportunely
before streaming, and I'm pretty sure you know what is the solution I
would propose for this :)

I've just gone through the same path with RPi's Unicam, that does the
same thing as your one does: it's an MC driver, but wants to control
the sensor through the v4l2-subdev kAPI to support legacy use cases
not covered by libcamera. The fact is that we're stuck in this limbo
where MC pipeline tries to decouple components one from each other and
delegate their configuration to userspace, but at the same time
vendors want to be able to use the simple plain video node centric
interface because of their existing user base, so I understand your
discomfort, but the 'simple plain' approach is what's preventing Linux
platforms to be in-par with proprietary and custom solutions for any
use case that is not a simple frame capture, so I think it's fair for
mainline to push for this evolution to happen. Just my2c of course.

Some more comments on the implementation below

> Changes in v5:
> - only in bindings
>
> Changes in v4:
> - now using get_mbus_config ops to get data from the subdevice, like the
> virtual channel id, and the clock type.
> - now having possibility to select any of the RAW10 data modes
> - at completion time, select which formats are also available in the subdevice,
> and move to the dynamic list accordingly
> - changed the pipeline integration, do not advertise subdev ready at probe time.
> wait until completion is done, and then start a workqueue that will register
> this device as a subdevice for the next element in pipeline.
> - moved the s_power code into a different function called now csi2dc_power
> that is called with CONFIG_PM functions. This is also called at completion,
> to have the device ready in case CONFIG_PM is not selected on the platform.
> - merged try_fmt into set_fmt
> - driver cleanup, wrapped lines over 80 characters
>
> Changes in v2:
> - moved driver to platform/atmel
> - fixed minor things as per Sakari's review
> - still some things from v2 review are not yet addressed, to be followed up
>
>  drivers/media/platform/atmel/Kconfig          |  13 +
>  drivers/media/platform/atmel/Makefile         |   1 +
>  .../media/platform/atmel/microchip-csi2dc.c   | 785 ++++++++++++++++++
>  3 files changed, 799 insertions(+)
>  create mode 100644 drivers/media/platform/atmel/microchip-csi2dc.c
>
> diff --git a/drivers/media/platform/atmel/Kconfig b/drivers/media/platform/atmel/Kconfig
> index 99b51213f871..147e1c14129b 100644
> --- a/drivers/media/platform/atmel/Kconfig
> +++ b/drivers/media/platform/atmel/Kconfig
> @@ -32,3 +32,16 @@ config VIDEO_ATMEL_ISI
>  	help
>  	  This module makes the ATMEL Image Sensor Interface available
>  	  as a v4l2 device.
> +
> +config VIDEO_MICROCHIP_CSI2DC
> +	tristate "Microchip CSI2 Demux Controller"
> +	depends on VIDEO_V4L2 && COMMON_CLK && OF
> +	depends on ARCH_AT91 || COMPILE_TEST
> +	select MEDIA_CONTROLLER
> +	select VIDEO_V4L2_SUBDEV_API
> +	select V4L2_FWNODE
> +	help
> +	  CSI2 Demux Controller driver. CSI2DC is a helper chip
> +	  that converts IDI interface byte stream to a parallel pixel stream.
> +	  It supports various RAW formats as input.
> +	  Performs clock domain crossing between hardware blocks.

Is the last phrase necessary ? Also missing the usual

	  To compile this driver as a module, choose M here: the
	  module will be called ...

> diff --git a/drivers/media/platform/atmel/Makefile b/drivers/media/platform/atmel/Makefile
> index c5c01556c653..8e80af500bf5 100644
> --- a/drivers/media/platform/atmel/Makefile
> +++ b/drivers/media/platform/atmel/Makefile
> @@ -5,3 +5,4 @@ atmel-xisc-objs = atmel-sama7g5-isc.o atmel-isc-base.o
>  obj-$(CONFIG_VIDEO_ATMEL_ISI) += atmel-isi.o
>  obj-$(CONFIG_VIDEO_ATMEL_ISC) += atmel-isc.o
>  obj-$(CONFIG_VIDEO_ATMEL_XISC) += atmel-xisc.o
> +obj-$(CONFIG_VIDEO_MICROCHIP_CSI2DC) += microchip-csi2dc.o
> diff --git a/drivers/media/platform/atmel/microchip-csi2dc.c b/drivers/media/platform/atmel/microchip-csi2dc.c
> new file mode 100644
> index 000000000000..fda1d5882dbb
> --- /dev/null
> +++ b/drivers/media/platform/atmel/microchip-csi2dc.c
> @@ -0,0 +1,785 @@
> +// SPDX-License-Identifier: GPL-2.0

Nit: I see GPL-2.0 listed as deprecated by spdx.org
Should you use one of:
        	GPL-2.0-only
               	GPL-2.0-or-later

> +/*
> + * Microchip CSI2 Demux Controller (CSI2DC) driver
> + *
> + * Copyright (C) 2018-2020 Microchip Technology, Inc.
> + *
> + * Author: Eugen Hristev <eugen.hristev@microchip.com>
> + *
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_graph.h>
> +#include <linux/platform_device.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/videodev2.h>
> +
> +#include <media/v4l2-device.h>
> +#include <media/v4l2-fwnode.h>
> +#include <media/v4l2-subdev.h>
> +#include <media/videobuf2-dma-contig.h>
> +
> +/* Global configuration register */
> +#define CSI2DC_GCFG			0x0
> +
> +/* MIPI sensor pixel clock is free running */
> +#define CSI2DC_GCFG_MIPIFRN		BIT(0)
> +/* Output waveform inter-line minimum delay */
> +#define CSI2DC_GCFG_HLC(v)		((v) << 4)
> +#define CSI2DC_GCFG_HLC_MASK		GENMASK(7, 4)
> +/* SAMA7G5 requires a HLC delay of 15 */
> +#define SAMA7G5_HLC			(15)
> +
> +/* Global control register */
> +#define CSI2DC_GCTLR			0x04
> +#define CSI2DC_GCTLR_SWRST		BIT(0)
> +
> +/* Global status register */
> +#define CSI2DC_GS			0x08
> +
> +/* SSP interrupt status register */
> +#define CSI2DC_SSPIS			0x28
> +/* Pipe update register */
> +#define CSI2DC_PU			0xC0
> +/* Video pipe attributes update */
> +#define CSI2DC_PU_VP			BIT(0)
> +
> +/* Pipe update status register */
> +#define CSI2DC_PUS			0xC4
> +
> +/* Video pipeline enable register */
> +#define CSI2DC_VPE			0xF8
> +#define CSI2DC_VPE_ENABLE		BIT(0)
> +
> +/* Video pipeline configuration register */
> +#define CSI2DC_VPCFG			0xFC
> +/* Data type */
> +#define CSI2DC_VPCFG_DT(v)		((v) << 0)
> +#define CSI2DC_VPCFG_DT_MASK		GENMASK(5, 0)
> +/* Virtual channel identifier */
> +#define CSI2DC_VPCFG_VC(v)		((v) << 6)
> +#define CSI2DC_VPCFG_VC_MASK		GENMASK(7, 6)
> +/* Decompression enable */
> +#define CSI2DC_VPCFG_DE			BIT(8)
> +/* Decoder mode */
> +#define CSI2DC_VPCFG_DM(v)		((v) << 9)
> +#define CSI2DC_VPCFG_DM_DECODER8TO12	0
> +/* Decoder predictor 2 selection */
> +#define CSI2DC_VPCFG_DP2		BIT(12)
> +/* Recommended memory storage */
> +#define CSI2DC_VPCFG_RMS		BIT(13)
> +/* Post adjustment */
> +#define CSI2DC_VPCFG_PA			BIT(14)
> +
> +/* Video pipeline column register */
> +#define CSI2DC_VPCOL			0x100
> +/* Column number */
> +#define CSI2DC_VPCOL_COL(v)		((v) << 0)
> +#define CSI2DC_VPCOL_COL_MASK		GENMASK(15, 0)
> +
> +/* Video pipeline row register */
> +#define CSI2DC_VPROW			0x104
> +/* Row number */
> +#define CSI2DC_VPROW_ROW(v)		((v) << 0)
> +#define CSI2DC_VPROW_ROW_MASK		GENMASK(15, 0)
> +
> +/* Version register */
> +#define CSI2DC_VERSION			0x1FC
> +
> +/* register read/write helpers */
> +#define csi2dc_readl(st, reg)		readl_relaxed((st)->base + (reg))
> +#define csi2dc_writel(st, reg, val)	writel_relaxed((val), \
> +					(st)->base + (reg))
> +
> +/* supported RAW data types */
> +#define CSI2DC_DT_RAW6			0x28
> +#define CSI2DC_DT_RAW7			0x29
> +#define CSI2DC_DT_RAW8			0x2A
> +#define CSI2DC_DT_RAW10			0x2B
> +#define CSI2DC_DT_RAW12			0x2C
> +#define CSI2DC_DT_RAW14			0x2D
> +
> +struct csi2dc_format {
> +	u32				mbus_code;
> +	u32				dt;
> +};
> +
> +static struct csi2dc_format csi2dc_formats_list[] = {
> +	{
> +		.mbus_code =		MEDIA_BUS_FMT_SRGGB10_1X10,
> +		.dt =			CSI2DC_DT_RAW10,
> +	}, {
> +		.mbus_code =		MEDIA_BUS_FMT_SBGGR10_1X10,
> +		.dt =			CSI2DC_DT_RAW10,
> +	}, {
> +		.mbus_code =		MEDIA_BUS_FMT_SGRBG10_1X10,
> +		.dt =			CSI2DC_DT_RAW10,
> +	}, {
> +		.mbus_code =		MEDIA_BUS_FMT_SGBRG10_1X10,
> +		.dt =			CSI2DC_DT_RAW10,
> +	},
> +};
> +
> +enum mipi_csi_pads {
> +	CSI2DC_PAD_SINK			= 0,
> +	CSI2DC_PAD_SOURCE		= 1,
> +	CSI2DC_PADS_NUM			= 2,
> +};
> +
> +struct csi2dc_device {
> +	void __iomem			*base;
> +	struct v4l2_subdev		csi2dc_sd;
> +	struct device			*dev;
> +	struct v4l2_device		v4l2_dev;
> +	struct clk			*pclk;
> +	struct clk			*scck;
> +
> +	bool				video_pipe;
> +
> +	u32				num_fmts;
> +	struct csi2dc_format		**formats;
> +
> +	struct csi2dc_format		*cur_fmt;
> +	struct csi2dc_format		*try_fmt;
> +
> +	struct media_pad		pads[CSI2DC_PADS_NUM];
> +
> +	bool				clk_gated;
> +	u32				vc;
> +
> +	struct v4l2_async_subdev	*asd;
> +	struct v4l2_async_notifier	notifier;
> +
> +	struct v4l2_subdev		*input_sd;
> +
> +	u32				remote_pad;
> +
> +	bool				completed;
> +	bool				powered_on;
> +
> +	struct work_struct		workq;
> +};
> +
> +static void csi2dc_vp_update(struct csi2dc_device *csi2dc)
> +{
> +	u32 vp;
> +
> +	vp = CSI2DC_VPCFG_DT(csi2dc->cur_fmt->dt) & CSI2DC_VPCFG_DT_MASK;
> +	vp |= CSI2DC_VPCFG_VC(csi2dc->vc) & CSI2DC_VPCFG_VC_MASK;
> +	vp &= ~CSI2DC_VPCFG_DE;
> +	vp |= CSI2DC_VPCFG_DM(CSI2DC_VPCFG_DM_DECODER8TO12);
> +	vp &= ~CSI2DC_VPCFG_DP2;
> +	vp &= ~CSI2DC_VPCFG_RMS;
> +	vp |= CSI2DC_VPCFG_PA;
> +
> +	csi2dc_writel(csi2dc, CSI2DC_VPCFG, vp);
> +	csi2dc_writel(csi2dc, CSI2DC_VPE, CSI2DC_VPE_ENABLE);
> +	csi2dc_writel(csi2dc, CSI2DC_PU, CSI2DC_PU_VP);
> +}
> +
> +static inline struct csi2dc_device *
> +csi2dc_sd_to_csi2dc_device(struct v4l2_subdev *csi2dc_sd)
> +{
> +	return container_of(csi2dc_sd, struct csi2dc_device, csi2dc_sd);
> +}
> +
> +static int csi2dc_enum_mbus_code(struct v4l2_subdev *csi2dc_sd,
> +				 struct v4l2_subdev_pad_config *cfg,
> +				 struct v4l2_subdev_mbus_code_enum *code)
> +{
> +	struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
> +
> +	if (code->index >= csi2dc->num_fmts)
> +		return -EINVAL;
> +
> +	code->code = csi2dc->formats[code->index]->mbus_code;
> +	return 0;
> +}
> +
> +static int csi2dc_set_fmt(struct v4l2_subdev *csi2dc_sd,
> +			  struct v4l2_subdev_pad_config *cfg,
> +			  struct v4l2_subdev_format *req_fmt)
> +{
> +	struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
> +	struct csi2dc_format *fmt;
> +	int ret, i;
> +
> +	if (!csi2dc->completed) {
> +		dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
> +		return 0;
> +	}
> +
> +	for (fmt = csi2dc->formats[0], i = 0; i < csi2dc->num_fmts; fmt++, i++)
> +		if (req_fmt->format.code == fmt->mbus_code)
> +			csi2dc->try_fmt = fmt;
> +
> +	/* in case we could not find the desired format, default to something */
> +	if (!csi2dc->try_fmt  ||
> +	    req_fmt->format.code != csi2dc->try_fmt->mbus_code) {
> +		csi2dc->try_fmt = csi2dc->formats[0];
> +
> +		dev_dbg(csi2dc->dev,
> +			"CSI2DC unsupported format 0x%x, defaulting to 0x%x\n",
> +			req_fmt->format.code, csi2dc->formats[0]->mbus_code);
> +
> +		req_fmt->format.code = csi2dc->formats[0]->mbus_code;
> +	}
> +
> +	/* if we are just trying, we are done */
> +	if (req_fmt->which == V4L2_SUBDEV_FORMAT_TRY)
> +		return 0;
> +
> +	ret = v4l2_subdev_call(csi2dc->input_sd, pad, set_fmt, cfg, req_fmt);
> +	if (ret) {
> +		dev_err(csi2dc->dev, "input subdev failed %d\n", ret);
> +		return ret;
> +	}
> +
> +	csi2dc->cur_fmt = csi2dc->try_fmt;
> +	/* update video pipe */
> +	csi2dc_vp_update(csi2dc);
> +
> +	dev_dbg(csi2dc->dev, "CSI2DC new format: 0x%x\n", req_fmt->format.code);
> +	return 0;
> +}
> +
> +static int csi2dc_formats_init(struct csi2dc_device *csi2dc)
> +{
> +	struct csi2dc_format *fmt;
> +	struct v4l2_subdev *subdev = csi2dc->input_sd;
> +	unsigned int num_fmts, i;
> +
> +	struct v4l2_subdev_mbus_code_enum mbus_code = {
> +		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
> +		.index = 0,
> +	};
> +
> +	num_fmts = 0;
> +
> +	csi2dc->formats = devm_kcalloc(csi2dc->dev,
> +				       ARRAY_SIZE(csi2dc_formats_list),
> +				       sizeof(*csi2dc->formats), GFP_KERNEL);
> +	if (!csi2dc->formats)
> +		return -ENOMEM;
> +
> +	while (!v4l2_subdev_call(subdev, pad, enum_mbus_code, NULL,
> +	       &mbus_code)) {
> +		mbus_code.index++;
> +		for (fmt = &csi2dc_formats_list[0], i = 0;
> +		     i < ARRAY_SIZE(csi2dc_formats_list); i++, fmt++)
> +			if (fmt->mbus_code == mbus_code.code) {
> +				csi2dc->formats[num_fmts] = fmt;
> +				num_fmts++;
> +			}
> +	}

For the reasons explained above and by Sakari, I think this should be dropped

> +
> +	if (!num_fmts)
> +		return -ENXIO;
> +
> +	csi2dc->num_fmts = num_fmts;
> +
> +	return 0;
> +}
> +
> +static int csi2dc_power(struct csi2dc_device *csi2dc, int on)
> +{
> +	int ret = 0;
> +
> +	if (!csi2dc->completed) {
> +		dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
> +		return 0;
> +	}

Can this happen ?

> +
> +	if (csi2dc->powered_on == on)
> +		return 0;

Same question

> +
> +	if (on)
> +		ret = clk_prepare_enable(csi2dc->scck);
> +	else
> +		clk_disable_unprepare(csi2dc->scck);
> +	if (ret)
> +		dev_err(csi2dc->dev, "failed to enable scck: %d\n", ret);
> +
> +	/* if powering up, deassert reset line */
> +	if (on)
> +		csi2dc_writel(csi2dc, CSI2DC_GCTLR, CSI2DC_GCTLR_SWRST);
> +
> +	/* if powering down, assert reset line */
> +	if (!on)
> +		csi2dc_writel(csi2dc, CSI2DC_GCTLR, !CSI2DC_GCTLR_SWRST);
> +	if (!ret)
> +		csi2dc->powered_on = on;

Wouldn't this be better coded as

        if (on) {
                clk_prepare_enable
                csi2dc_writel(SWRST)
                powered_on = true
        } else {
                clk_disable_unrepare
                csi2dc_writel(!SWRST)
                powered_on = false
        }
> +
> +	return ret;
> +}
> +
> +static int csi2dc_s_stream(struct v4l2_subdev *csi2dc_sd, int enable)
> +{
> +	struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
> +
> +	if (!csi2dc->completed) {
> +		dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
> +		return 0;
> +	}
> +
> +	return v4l2_subdev_call(csi2dc->input_sd, video, s_stream, enable);
> +}
> +
> +static int csi2dc_g_frame_interval(struct v4l2_subdev *csi2dc_sd,
> +				   struct v4l2_subdev_frame_interval *interval)
> +{
> +	struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
> +
> +	if (!csi2dc->completed) {
> +		dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
> +		return 0;
> +	}
> +
> +	return v4l2_subdev_call(csi2dc->input_sd, video, g_frame_interval,
> +				interval);
> +}
> +
> +static int csi2dc_s_frame_interval(struct v4l2_subdev *csi2dc_sd,
> +				   struct v4l2_subdev_frame_interval *interval)
> +{
> +	struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
> +
> +	if (!csi2dc->completed) {
> +		dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
> +		return 0;
> +	}
> +
> +	return v4l2_subdev_call(csi2dc->input_sd, video, s_frame_interval,
> +				interval);
> +}
> +
> +static int csi2dc_enum_frame_size(struct v4l2_subdev *csi2dc_sd,
> +				  struct v4l2_subdev_pad_config *cfg,
> +				  struct v4l2_subdev_frame_size_enum *fse)
> +{
> +	struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
> +
> +	if (!csi2dc->completed) {
> +		dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
> +		return 0;
> +	}
> +
> +	return v4l2_subdev_call(csi2dc->input_sd, pad, enum_frame_size, cfg,
> +				fse);
> +}
> +
> +static int csi2dc_enum_frame_interval(struct v4l2_subdev *csi2dc_sd,
> +			      struct v4l2_subdev_pad_config *cfg,
> +			      struct v4l2_subdev_frame_interval_enum *fie)
> +{
> +	struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
> +
> +	if (!csi2dc->completed) {
> +		dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
> +		return 0;
> +	}
> +
> +	return v4l2_subdev_call(csi2dc->input_sd, pad, enum_frame_interval, cfg,
> +				fie);
> +}
> +
> +static const struct v4l2_subdev_pad_ops csi2dc_pad_ops = {
> +	.enum_mbus_code = csi2dc_enum_mbus_code,
> +	.set_fmt = csi2dc_set_fmt,
> +	.enum_frame_size = csi2dc_enum_frame_size,
> +	.enum_frame_interval = csi2dc_enum_frame_interval,
> +};
> +
> +static const struct v4l2_subdev_video_ops csi2dc_video_ops = {
> +	.s_stream = csi2dc_s_stream,
> +	.g_frame_interval = csi2dc_g_frame_interval,
> +	.s_frame_interval = csi2dc_s_frame_interval,
> +};
> +
> +static const struct v4l2_subdev_ops csi2dc_subdev_ops = {
> +	.pad = &csi2dc_pad_ops,
> +	.video = &csi2dc_video_ops,
> +};
> +
> +static int csi2dc_get_mbus_config(struct csi2dc_device *csi2dc)
> +{
> +	struct v4l2_mbus_config mbus_config = { 0 };
> +	int ret;
> +
> +	ret = v4l2_subdev_call(csi2dc->input_sd, pad, get_mbus_config,
> +			       csi2dc->remote_pad, &mbus_config);
> +	if (ret == -ENOIOCTLCMD) {
> +		dev_dbg(csi2dc->dev,
> +			"no remote mbus configuration available\n");
> +		goto csi2dc_get_mbus_config_defaults;
> +	}
> +
> +	if (ret) {
> +		dev_err(csi2dc->dev,
> +			"failed to get remote mbus configuration\n");
> +		goto csi2dc_get_mbus_config_defaults;

This should probably be an error reported to the caller. But this
function return value is not checked, so it's probably fine.

> +	}
> +
> +	if (mbus_config.flags & V4L2_MBUS_CSI2_CHANNEL_0)
> +		csi2dc->vc = 0;
> +	else if (mbus_config.flags & V4L2_MBUS_CSI2_CHANNEL_1)
> +		csi2dc->vc = 1;
> +	else if (mbus_config.flags & V4L2_MBUS_CSI2_CHANNEL_2)
> +		csi2dc->vc = 2;
> +	else if (mbus_config.flags & V4L2_MBUS_CSI2_CHANNEL_3)
> +		csi2dc->vc = 3;
> +
> +	dev_dbg(csi2dc->dev, "subdev sending on channel %d\n", csi2dc->vc);
> +
> +	csi2dc->clk_gated = mbus_config.flags &
> +			    V4L2_MBUS_CSI2_NONCONTINUOUS_CLOCK;
> +
> +	dev_dbg(csi2dc->dev, "%s clock\n",
> +		csi2dc->clk_gated ? "gated" : "free running");
> +
> +	return 0;
> +
> +csi2dc_get_mbus_config_defaults:
> +	csi2dc->vc = 0; /* Virtual ID 0 by default */
> +	csi2dc->clk_gated = false; /* Free running clock by default */
> +
> +	return 0;
> +}
> +
> +static int csi2dc_async_bound(struct v4l2_async_notifier *notifier,
> +			      struct v4l2_subdev *subdev,
> +			      struct v4l2_async_subdev *asd)
> +{
> +	struct csi2dc_device *csi2dc = container_of(notifier->v4l2_dev,
> +					struct csi2dc_device, v4l2_dev);
> +	int pad;
> +
> +	csi2dc->input_sd = subdev;
> +
> +	pad = media_entity_get_fwnode_pad(&subdev->entity,
> +					  asd->match.fwnode,
> +					  MEDIA_PAD_FL_SOURCE);
> +	if (pad < 0) {
> +		dev_err(csi2dc->dev, "Failed to find pad for %s\n",
> +			subdev->name);
> +		return pad;
> +	}
> +
> +	csi2dc->remote_pad = pad;
> +
> +	csi2dc_get_mbus_config(csi2dc);

The closer to s_stream you call get_mbus_config, the less the chances
of receiving a stale configuration, if this can happen.

> +
> +	return 0;
> +}
> +
> +static int csi2dc_async_complete(struct v4l2_async_notifier *notifier)
> +{
> +	struct csi2dc_device *csi2dc =
> +		container_of(notifier->v4l2_dev, struct csi2dc_device,
> +			     v4l2_dev);
> +	int ret;
> +
> +	ret = csi2dc_formats_init(csi2dc);
> +	if (ret)
> +		return ret;
> +
> +	ret = v4l2_device_register_subdev_nodes(&csi2dc->v4l2_dev);
> +	if (ret < 0) {
> +		v4l2_err(&csi2dc->v4l2_dev,
> +			 "failed to register subdev nodes\n");
> +		return ret;
> +	}
> +
> +	csi2dc->completed = true;
> +
> +	csi2dc_writel(csi2dc, CSI2DC_GCFG,
> +		      (SAMA7G5_HLC & CSI2DC_GCFG_HLC_MASK) |
> +		      (csi2dc->clk_gated ? 0 : CSI2DC_GCFG_MIPIFRN));
> +
> +	csi2dc_writel(csi2dc, CSI2DC_VPCOL,
> +		      CSI2DC_VPCOL_COL(0xFFF) & CSI2DC_VPCOL_COL_MASK);
> +	csi2dc_writel(csi2dc, CSI2DC_VPROW,
> +		      CSI2DC_VPROW_ROW(0xFFF) & CSI2DC_VPROW_ROW_MASK);
> +
> +	/* once we are completed, we can register ourselves in the pipeline */
> +	schedule_work(&csi2dc->workq);
> +
> +	return ret;
> +}
> +
> +static const struct v4l2_async_notifier_operations csi2dc_async_ops = {
> +	.bound = csi2dc_async_bound,
> +	.complete = csi2dc_async_complete,
> +};
> +
> +static void csi2dc_cleanup_notifier(struct csi2dc_device *csi2dc)
> +{
> +	v4l2_async_notifier_unregister(&csi2dc->notifier);
> +	v4l2_async_notifier_cleanup(&csi2dc->notifier);
> +}
> +
> +static int csi2dc_prepare_notifier(struct csi2dc_device *csi2dc,
> +				   struct device_node *input_parent)
> +{
> +	int ret;
> +
> +	v4l2_async_notifier_init(&csi2dc->notifier);
> +
> +	csi2dc->asd = kzalloc(sizeof(*csi2dc->asd), GFP_KERNEL);
> +	if (!csi2dc->asd)
> +		return -ENOMEM;
> +
> +	csi2dc->asd->match_type = V4L2_ASYNC_MATCH_FWNODE;
> +	csi2dc->asd->match.fwnode = of_fwnode_handle(input_parent);

If you use v4l2_async_notifier_add_fwnode_subdev() the framework does
this for you.

> +
> +	ret = v4l2_async_notifier_add_subdev(&csi2dc->notifier, csi2dc->asd);
> +	if (ret) {
> +		dev_err(csi2dc->dev, "failed to add async notifier.\n");
> +		v4l2_async_notifier_cleanup(&csi2dc->notifier);
> +		goto csi2dc_prepare_notifier_err;
> +	}
> +
> +	csi2dc->notifier.ops = &csi2dc_async_ops;
> +
> +	ret = v4l2_async_notifier_register(&csi2dc->v4l2_dev,
> +					   &csi2dc->notifier);
> +
> +	if (ret) {
> +		dev_err(csi2dc->dev, "fail to register async notifier.\n");

Shouldn't you cleanup the notifier if registration fails ?

> +		goto csi2dc_prepare_notifier_err;
> +	}
> +
> +csi2dc_prepare_notifier_err:
> +	of_node_put(input_parent);
> +
> +	return ret;
> +}
> +
> +static int csi2dc_of_parse(struct csi2dc_device *csi2dc,
> +			   struct device_node *of_node)
> +{
> +	struct device_node *input_node, *sink_node, *input_parent;
> +	struct v4l2_fwnode_endpoint input_endpoint = { 0 },
> +				    sink_endpoint = { 0 };
> +	int ret;
> +
> +	input_node = of_graph_get_next_endpoint(of_node, NULL);
> +
> +	if (!input_node) {
> +		dev_err(csi2dc->dev,
> +			"missing port node at %s, input node is mandatory.\n",

Please use %pOF to print the node name
Also, input_node should be put in the error path

> +			of_node->full_name);
> +		return -EINVAL;
> +	}
> +
> +	ret = v4l2_fwnode_endpoint_parse(of_fwnode_handle(input_node),
> +					 &input_endpoint);

Please set input_endpoint.bus_type if you know what kind of bus you're
dealing with (not having the bindings of the IDI transmitter I'm not
sure. Is this V4L2_MBUS_CSI2_DPHY ?)

> +
> +	if (ret) {
> +		dev_err(csi2dc->dev, "endpoint not defined at %s\n",
> +			of_node->full_name);
> +		return ret;
> +	}
> +
> +	input_parent = of_graph_get_remote_port_parent(input_node);
> +	if (!input_parent) {

Missing of_node_put(input_node)

> +		dev_err(csi2dc->dev,
> +			"could not get input node's parent node.\n");
> +		return -EINVAL;
> +	}
> +
> +	sink_node = of_graph_get_next_endpoint(of_node, input_node);
> +
> +	if (sink_node)
> +		ret = v4l2_fwnode_endpoint_parse(of_fwnode_handle(sink_node),
> +						 &sink_endpoint);

Same, set sink_endpoint.bus_type if you know it's MBUS_PARALLEL

> +
> +	if (!sink_node || ret) {

If parsing fail you don't return an error but continue registering the
notifier and potentially end up registering the async subdev for this
entity even if the endpoint parsing failed.

> +		dev_info(csi2dc->dev,
> +			 "missing sink node at %s, data pipe available only.\n",
> +			 of_node->full_name);
> +	} else {
> +		csi2dc->video_pipe = true;

video_pipe is unused it seems

> +
> +		dev_dbg(csi2dc->dev, "block %s %d.%d->%d.%d video pipeline\n",
> +			of_node->full_name, input_endpoint.base.port,
> +			input_endpoint.base.id,	sink_endpoint.base.port,
> +			sink_endpoint.base.id);
> +	}
> +
> +	of_node_put(sink_node);
> +	of_node_put(input_node);
> +
> +	/* prepare async notifier for subdevice completion */
> +	return csi2dc_prepare_notifier(csi2dc, input_parent);
> +}
> +
> +static void csi2dc_workq_handler(struct work_struct *workq)
> +{
> +	struct csi2dc_device *csi2dc = container_of(workq,
> +					struct csi2dc_device, workq);
> +	int ret;
> +
> +	if (v4l2_async_register_subdev(&csi2dc->csi2dc_sd))
> +		dev_dbg(csi2dc->dev, "failed to register the subdevice\n");

That's peculiar, why do you have to schedule this to a workqueue
instead of doing this in the complete() callback ?

> +
> +	ret = csi2dc_power(csi2dc, true);
> +	if (ret < 0)
> +		v4l2_err(&csi2dc->v4l2_dev, "failed to power on\n");

Should the device be powered on at s_stream time ? Possibly with a
pm_runtime_get_sync() call ? I see you register pm_runtime operations,
but never call get_sync() or _put().

What if CONFIG_PM not selected ? Should this driver select it ? Do you
have use cases where that's not possible ?

> +}
> +
> +static int csi2dc_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct csi2dc_device *csi2dc;
> +	struct resource *res = NULL;
> +	int ret = 0;
> +
> +	csi2dc = devm_kzalloc(dev, sizeof(*csi2dc), GFP_KERNEL);
> +	if (!csi2dc)
> +		return -ENOMEM;
> +
> +	csi2dc->dev = dev;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!res)
> +		return -EINVAL;

devm_ioremap_resource() checks for the validity of 'res' so you can
drop the previous two lines

> +
> +	csi2dc->base = devm_ioremap_resource(dev, res);
> +

Is the empy line intentional, sometimes you have one, sometimes you
don't ?

> +	if (IS_ERR(csi2dc->base)) {
> +		dev_err(dev, "base address not set\n");


> +		return PTR_ERR(csi2dc->base);
> +	}
> +
> +	csi2dc->pclk = devm_clk_get(dev, "pclk");
> +	if (IS_ERR(csi2dc->pclk)) {
> +		ret = PTR_ERR(csi2dc->pclk);
> +		dev_err(dev, "failed to get pclk: %d\n", ret);
> +		return ret;

Just return PTR_ERR instead of assigning to ret

> +	}
> +
> +	ret = clk_prepare_enable(csi2dc->pclk);
> +	if (ret) {
> +		dev_err(dev, "failed to enable pclk: %d\n", ret);
> +		return ret;
> +	}

Has this clock to be enabled here or can it be done in the
pm_runtime callback ?

> +
> +	csi2dc->scck = devm_clk_get(dev, "scck");
> +	if (IS_ERR(csi2dc->scck)) {
> +		ret = PTR_ERR(csi2dc->scck);
> +		dev_err(dev, "failed to get scck: %d\n", ret);
> +		goto csi2dc_clk_fail;
> +	}
> +
> +	ret = v4l2_device_register(dev, &csi2dc->v4l2_dev);
> +	if (ret) {
> +		dev_err(dev, "unable to register v4l2 device.\n");
> +		goto csi2dc_clk_fail;
> +	}
> +
> +	v4l2_subdev_init(&csi2dc->csi2dc_sd, &csi2dc_subdev_ops);
> +
> +	csi2dc->csi2dc_sd.owner = THIS_MODULE;
> +	csi2dc->csi2dc_sd.dev = dev;
> +	snprintf(csi2dc->csi2dc_sd.name, sizeof(csi2dc->csi2dc_sd.name),
> +		 "CSI2DC.0");
> +
> +	csi2dc->csi2dc_sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
> +	csi2dc->csi2dc_sd.entity.function = MEDIA_ENT_F_VID_IF_BRIDGE;
> +	csi2dc->pads[CSI2DC_PAD_SINK].flags = MEDIA_PAD_FL_SINK;
> +	csi2dc->pads[CSI2DC_PAD_SOURCE].flags = MEDIA_PAD_FL_SOURCE;

Isn't the source pad presence conditional to the presence of
port@1 ?

> +
> +	ret = media_entity_pads_init(&csi2dc->csi2dc_sd.entity, CSI2DC_PADS_NUM,
> +				     csi2dc->pads);
> +	if (ret < 0) {
> +		dev_err(dev, "media entity init failed\n");
> +		goto csi2dc_probe_entity_err;
> +	}
> +
> +	v4l2_set_subdevdata(&csi2dc->csi2dc_sd, pdev);
> +
> +	platform_set_drvdata(pdev, &csi2dc->csi2dc_sd);
> +
> +	INIT_WORK(&csi2dc->workq, csi2dc_workq_handler);
> +
> +	ret = csi2dc_of_parse(csi2dc, dev->of_node);
> +	if (ret)
> +		goto csi2dc_probe_entity_err;
> +
> +	dev_info(dev, "Microchip CSI2DC version %x\n",
> +		 csi2dc_readl(csi2dc, CSI2DC_VERSION));
> +
> +	pm_runtime_set_active(dev);
> +	pm_runtime_enable(dev);
> +	pm_request_idle(dev);
> +
> +	return 0;
> +
> +csi2dc_probe_entity_err:
> +	media_entity_cleanup(&csi2dc->csi2dc_sd.entity);
> +	v4l2_device_unregister(&csi2dc->v4l2_dev);
> +csi2dc_clk_fail:
> +	clk_disable_unprepare(csi2dc->pclk);
> +	return ret;
> +}
> +
> +static int csi2dc_remove(struct platform_device *pdev)
> +{
> +	struct v4l2_subdev *csi2dc_sd = platform_get_drvdata(pdev);
> +	struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
> +
> +	pm_runtime_disable(&pdev->dev);
> +
> +	v4l2_async_unregister_subdev(&csi2dc->csi2dc_sd);
> +	csi2dc_cleanup_notifier(csi2dc);
> +	media_entity_cleanup(&csi2dc->csi2dc_sd.entity);
> +	v4l2_device_unregister(&csi2dc->v4l2_dev);
> +	clk_disable_unprepare(csi2dc->pclk);
> +
> +	return 0;
> +}
> +
> +static int __maybe_unused csi2dc_runtime_suspend(struct device *dev)
> +{
> +	struct csi2dc_device *csi2dc = dev_get_drvdata(dev);
> +
> +	return csi2dc_power(csi2dc, false);
> +}
> +
> +static int __maybe_unused csi2dc_runtime_resume(struct device *dev)
> +{
> +	struct csi2dc_device *csi2dc = dev_get_drvdata(dev);
> +
> +	return csi2dc_power(csi2dc, true);
> +}
> +
> +static const struct dev_pm_ops csi2dc_dev_pm_ops = {
> +	SET_RUNTIME_PM_OPS(csi2dc_runtime_suspend, csi2dc_runtime_resume, NULL)
> +};
> +
> +static const struct of_device_id csi2dc_of_match[] = {
> +	{ .compatible = "microchip,sama7g5-csi2dc" },
> +	{ }
> +};
> +
> +MODULE_DEVICE_TABLE(of, csi2dc_of_match);
> +
> +static struct platform_driver csi2dc_driver = {
> +	.probe	= csi2dc_probe,
> +	.remove	= csi2dc_remove,
> +	.driver	= {
> +		.name		= "microchip-csi2dc",
> +		.pm		= &csi2dc_dev_pm_ops,
> +		.of_match_table = of_match_ptr(csi2dc_of_match),
> +	},
> +};
> +
> +module_platform_driver(csi2dc_driver);
> +
> +MODULE_AUTHOR("Eugen Hristev <eugen.hristev@microchip.com>");
> +MODULE_DESCRIPTION("Microchip CSI2 Demux Controller driver");
> +MODULE_LICENSE("GPL v2");
> +MODULE_SUPPORTED_DEVICE("video");

For my education, what's MODULE_SUPPORTED_DEVICE for ?

Thanks
  j

> --
> 2.25.1
>

Re: [PATCH v5 2/3] media: atmel: introduce microchip csi2dc driver

[Laurent Pinchart]

Hello everybody,

On Tue, Nov 17, 2020 at 12:59:02PM +0100, Jacopo Mondi wrote:
> On Thu, Nov 12, 2020 at 03:34:36PM +0200, Eugen Hristev wrote:
> > Microchip CSI2DC (CSI2 Demultiplexer Controller) is a misc bridge device
> > that converts a byte stream in IDI Synopsys format (coming from a CSI2HOST)
> > to a pixel stream that can be captured by a sensor controller.
> >
> > Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
> > ---
> > Hello,
> >
> > There still are some open questions regarding the last reviews on the ML.
> >
> > Regarding the format list which is not const, I cannot have it const because
> > I reference elements from this list into a dynamic list which is non-const.
> >
> > Regarding the presence of the v4l2_dev, without this I cannot add a notifier
> > for this device to have it async completed , when the underlying subdevice
> > finishes probing.
> 
> I see you have a discussion with Sakari on-going on this, and I have
> the very same comment he had.
> 
> Should a sub-notifier be used and this driver should not register any
> v4l2_dev but integrate in the media graph of the receiver ?
> 
> For reference, rcar-csi2 uses sub-notifiers and register in the
> rcar-vin media graph, it doesn't need to set up a v4l2_dev.
> 
> rcar-vin (the DMA engine driver) that register video nodes and the v4l2-dev
> also registers the device nodes for all the connected subdevices.

Sub-notifiers were invited for this purpose, so I think they're the
right tool.

> > Regarding the callbacks for set frame interval, set frame size, etc, I cannot
> > remove them because losing functionality to the underlying subdevice, as
> > explained in :
> > https://lkml.org/lkml/2020/10/12/427
> 
> Using the frame sizes as in the example you reported, if this device has
> limitations on the supported sizes, (a min and a max most
> probably) that's the only thing that should be exposed from this
> driver subdevice. The sensor subdevice instead will report the
> available discrete sizes and userspace configures the sensor's source
> pad and the bridge's sink pad with the same sizes to properly set up the
> capture pipeline. video0 should not report the sizes exposed by the sensor
> nor any information that depends on what's connected to it.

Agreed. Subdev drivers should remain simple and cover only the subdev
they manage. Bundling it together is the job of userspace. In the legacy
model it uses to be the job of the top-level V4L2 driver (the one
implementing v4l2_device), but that's legacy, especially for embedded
camera use cases. In any case, the top-level logic must not be spread
across subdevices.

> I know what your next question is: what about existing application
> that only know about video0 and want to setup everything from there. I
> understand vendors not wanting to wrap gstreamer or what is used in
> the wild in custom scripts that sets up the pipeline opportunely
> before streaming, and I'm pretty sure you know what is the solution I
> would propose for this :)
> 
> I've just gone through the same path with RPi's Unicam, that does the
> same thing as your one does: it's an MC driver, but wants to control
> the sensor through the v4l2-subdev kAPI to support legacy use cases
> not covered by libcamera. The fact is that we're stuck in this limbo
> where MC pipeline tries to decouple components one from each other and
> delegate their configuration to userspace, but at the same time
> vendors want to be able to use the simple plain video node centric
> interface because of their existing user base, so I understand your
> discomfort, but the 'simple plain' approach is what's preventing Linux
> platforms to be in-par with proprietary and custom solutions for any
> use case that is not a simple frame capture, so I think it's fair for
> mainline to push for this evolution to happen. Just my2c of course.

Compatibility with the userspace of downstream kernels is important, but
that's a downstream kernel issue. In mainline we want to go the MC way,
and downstream can then, if desired, implement the configuration of the
pipeline in the top-level V4L2 driver in the kernel to support the
existing userbase. For new drivers I wouldn't recommend that, for
existing downstream drivers it may be required.

> Some more comments on the implementation below
> 
> > Changes in v5:
> > - only in bindings
> >
> > Changes in v4:
> > - now using get_mbus_config ops to get data from the subdevice, like the
> > virtual channel id, and the clock type.
> > - now having possibility to select any of the RAW10 data modes
> > - at completion time, select which formats are also available in the subdevice,
> > and move to the dynamic list accordingly
> > - changed the pipeline integration, do not advertise subdev ready at probe time.
> > wait until completion is done, and then start a workqueue that will register
> > this device as a subdevice for the next element in pipeline.
> > - moved the s_power code into a different function called now csi2dc_power
> > that is called with CONFIG_PM functions. This is also called at completion,
> > to have the device ready in case CONFIG_PM is not selected on the platform.
> > - merged try_fmt into set_fmt
> > - driver cleanup, wrapped lines over 80 characters
> >
> > Changes in v2:
> > - moved driver to platform/atmel
> > - fixed minor things as per Sakari's review
> > - still some things from v2 review are not yet addressed, to be followed up
> >
> >  drivers/media/platform/atmel/Kconfig          |  13 +
> >  drivers/media/platform/atmel/Makefile         |   1 +
> >  .../media/platform/atmel/microchip-csi2dc.c   | 785 ++++++++++++++++++
> >  3 files changed, 799 insertions(+)
> >  create mode 100644 drivers/media/platform/atmel/microchip-csi2dc.c
> >
> > diff --git a/drivers/media/platform/atmel/Kconfig b/drivers/media/platform/atmel/Kconfig
> > index 99b51213f871..147e1c14129b 100644
> > --- a/drivers/media/platform/atmel/Kconfig
> > +++ b/drivers/media/platform/atmel/Kconfig
> > @@ -32,3 +32,16 @@ config VIDEO_ATMEL_ISI
> >  	help
> >  	  This module makes the ATMEL Image Sensor Interface available
> >  	  as a v4l2 device.
> > +
> > +config VIDEO_MICROCHIP_CSI2DC
> > +	tristate "Microchip CSI2 Demux Controller"
> > +	depends on VIDEO_V4L2 && COMMON_CLK && OF
> > +	depends on ARCH_AT91 || COMPILE_TEST
> > +	select MEDIA_CONTROLLER
> > +	select VIDEO_V4L2_SUBDEV_API
> > +	select V4L2_FWNODE
> > +	help
> > +	  CSI2 Demux Controller driver. CSI2DC is a helper chip
> > +	  that converts IDI interface byte stream to a parallel pixel stream.
> > +	  It supports various RAW formats as input.
> > +	  Performs clock domain crossing between hardware blocks.
> 
> Is the last phrase necessary ? Also missing the usual
> 
> 	  To compile this driver as a module, choose M here: the
> 	  module will be called ...
> 
> > diff --git a/drivers/media/platform/atmel/Makefile b/drivers/media/platform/atmel/Makefile
> > index c5c01556c653..8e80af500bf5 100644
> > --- a/drivers/media/platform/atmel/Makefile
> > +++ b/drivers/media/platform/atmel/Makefile
> > @@ -5,3 +5,4 @@ atmel-xisc-objs = atmel-sama7g5-isc.o atmel-isc-base.o
> >  obj-$(CONFIG_VIDEO_ATMEL_ISI) += atmel-isi.o
> >  obj-$(CONFIG_VIDEO_ATMEL_ISC) += atmel-isc.o
> >  obj-$(CONFIG_VIDEO_ATMEL_XISC) += atmel-xisc.o
> > +obj-$(CONFIG_VIDEO_MICROCHIP_CSI2DC) += microchip-csi2dc.o
> > diff --git a/drivers/media/platform/atmel/microchip-csi2dc.c b/drivers/media/platform/atmel/microchip-csi2dc.c
> > new file mode 100644
> > index 000000000000..fda1d5882dbb
> > --- /dev/null
> > +++ b/drivers/media/platform/atmel/microchip-csi2dc.c
> > @@ -0,0 +1,785 @@
> > +// SPDX-License-Identifier: GPL-2.0
> 
> Nit: I see GPL-2.0 listed as deprecated by spdx.org
> Should you use one of:
>         	GPL-2.0-only
>                	GPL-2.0-or-later
> 
> > +/*
> > + * Microchip CSI2 Demux Controller (CSI2DC) driver
> > + *
> > + * Copyright (C) 2018-2020 Microchip Technology, Inc.
> > + *
> > + * Author: Eugen Hristev <eugen.hristev@microchip.com>
> > + *
> > + */
> > +
> > +#include <linux/clk.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/of_graph.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/pm_runtime.h>
> > +#include <linux/videodev2.h>
> > +
> > +#include <media/v4l2-device.h>
> > +#include <media/v4l2-fwnode.h>
> > +#include <media/v4l2-subdev.h>
> > +#include <media/videobuf2-dma-contig.h>
> > +
> > +/* Global configuration register */
> > +#define CSI2DC_GCFG			0x0
> > +
> > +/* MIPI sensor pixel clock is free running */
> > +#define CSI2DC_GCFG_MIPIFRN		BIT(0)
> > +/* Output waveform inter-line minimum delay */
> > +#define CSI2DC_GCFG_HLC(v)		((v) << 4)
> > +#define CSI2DC_GCFG_HLC_MASK		GENMASK(7, 4)
> > +/* SAMA7G5 requires a HLC delay of 15 */
> > +#define SAMA7G5_HLC			(15)
> > +
> > +/* Global control register */
> > +#define CSI2DC_GCTLR			0x04
> > +#define CSI2DC_GCTLR_SWRST		BIT(0)
> > +
> > +/* Global status register */
> > +#define CSI2DC_GS			0x08
> > +
> > +/* SSP interrupt status register */
> > +#define CSI2DC_SSPIS			0x28
> > +/* Pipe update register */
> > +#define CSI2DC_PU			0xC0
> > +/* Video pipe attributes update */
> > +#define CSI2DC_PU_VP			BIT(0)
> > +
> > +/* Pipe update status register */
> > +#define CSI2DC_PUS			0xC4
> > +
> > +/* Video pipeline enable register */
> > +#define CSI2DC_VPE			0xF8
> > +#define CSI2DC_VPE_ENABLE		BIT(0)
> > +
> > +/* Video pipeline configuration register */
> > +#define CSI2DC_VPCFG			0xFC
> > +/* Data type */
> > +#define CSI2DC_VPCFG_DT(v)		((v) << 0)
> > +#define CSI2DC_VPCFG_DT_MASK		GENMASK(5, 0)
> > +/* Virtual channel identifier */
> > +#define CSI2DC_VPCFG_VC(v)		((v) << 6)
> > +#define CSI2DC_VPCFG_VC_MASK		GENMASK(7, 6)
> > +/* Decompression enable */
> > +#define CSI2DC_VPCFG_DE			BIT(8)
> > +/* Decoder mode */
> > +#define CSI2DC_VPCFG_DM(v)		((v) << 9)
> > +#define CSI2DC_VPCFG_DM_DECODER8TO12	0
> > +/* Decoder predictor 2 selection */
> > +#define CSI2DC_VPCFG_DP2		BIT(12)
> > +/* Recommended memory storage */
> > +#define CSI2DC_VPCFG_RMS		BIT(13)
> > +/* Post adjustment */
> > +#define CSI2DC_VPCFG_PA			BIT(14)
> > +
> > +/* Video pipeline column register */
> > +#define CSI2DC_VPCOL			0x100
> > +/* Column number */
> > +#define CSI2DC_VPCOL_COL(v)		((v) << 0)
> > +#define CSI2DC_VPCOL_COL_MASK		GENMASK(15, 0)
> > +
> > +/* Video pipeline row register */
> > +#define CSI2DC_VPROW			0x104
> > +/* Row number */
> > +#define CSI2DC_VPROW_ROW(v)		((v) << 0)
> > +#define CSI2DC_VPROW_ROW_MASK		GENMASK(15, 0)
> > +
> > +/* Version register */
> > +#define CSI2DC_VERSION			0x1FC
> > +
> > +/* register read/write helpers */
> > +#define csi2dc_readl(st, reg)		readl_relaxed((st)->base + (reg))
> > +#define csi2dc_writel(st, reg, val)	writel_relaxed((val), \
> > +					(st)->base + (reg))
> > +
> > +/* supported RAW data types */
> > +#define CSI2DC_DT_RAW6			0x28
> > +#define CSI2DC_DT_RAW7			0x29
> > +#define CSI2DC_DT_RAW8			0x2A
> > +#define CSI2DC_DT_RAW10			0x2B
> > +#define CSI2DC_DT_RAW12			0x2C
> > +#define CSI2DC_DT_RAW14			0x2D
> > +
> > +struct csi2dc_format {
> > +	u32				mbus_code;
> > +	u32				dt;
> > +};
> > +
> > +static struct csi2dc_format csi2dc_formats_list[] = {
> > +	{
> > +		.mbus_code =		MEDIA_BUS_FMT_SRGGB10_1X10,
> > +		.dt =			CSI2DC_DT_RAW10,
> > +	}, {
> > +		.mbus_code =		MEDIA_BUS_FMT_SBGGR10_1X10,
> > +		.dt =			CSI2DC_DT_RAW10,
> > +	}, {
> > +		.mbus_code =		MEDIA_BUS_FMT_SGRBG10_1X10,
> > +		.dt =			CSI2DC_DT_RAW10,
> > +	}, {
> > +		.mbus_code =		MEDIA_BUS_FMT_SGBRG10_1X10,
> > +		.dt =			CSI2DC_DT_RAW10,
> > +	},
> > +};
> > +
> > +enum mipi_csi_pads {
> > +	CSI2DC_PAD_SINK			= 0,
> > +	CSI2DC_PAD_SOURCE		= 1,
> > +	CSI2DC_PADS_NUM			= 2,
> > +};
> > +
> > +struct csi2dc_device {
> > +	void __iomem			*base;
> > +	struct v4l2_subdev		csi2dc_sd;
> > +	struct device			*dev;
> > +	struct v4l2_device		v4l2_dev;
> > +	struct clk			*pclk;
> > +	struct clk			*scck;
> > +
> > +	bool				video_pipe;
> > +
> > +	u32				num_fmts;
> > +	struct csi2dc_format		**formats;
> > +
> > +	struct csi2dc_format		*cur_fmt;
> > +	struct csi2dc_format		*try_fmt;
> > +
> > +	struct media_pad		pads[CSI2DC_PADS_NUM];
> > +
> > +	bool				clk_gated;
> > +	u32				vc;
> > +
> > +	struct v4l2_async_subdev	*asd;
> > +	struct v4l2_async_notifier	notifier;
> > +
> > +	struct v4l2_subdev		*input_sd;
> > +
> > +	u32				remote_pad;
> > +
> > +	bool				completed;
> > +	bool				powered_on;
> > +
> > +	struct work_struct		workq;
> > +};
> > +
> > +static void csi2dc_vp_update(struct csi2dc_device *csi2dc)
> > +{
> > +	u32 vp;
> > +
> > +	vp = CSI2DC_VPCFG_DT(csi2dc->cur_fmt->dt) & CSI2DC_VPCFG_DT_MASK;
> > +	vp |= CSI2DC_VPCFG_VC(csi2dc->vc) & CSI2DC_VPCFG_VC_MASK;
> > +	vp &= ~CSI2DC_VPCFG_DE;
> > +	vp |= CSI2DC_VPCFG_DM(CSI2DC_VPCFG_DM_DECODER8TO12);
> > +	vp &= ~CSI2DC_VPCFG_DP2;
> > +	vp &= ~CSI2DC_VPCFG_RMS;
> > +	vp |= CSI2DC_VPCFG_PA;
> > +
> > +	csi2dc_writel(csi2dc, CSI2DC_VPCFG, vp);
> > +	csi2dc_writel(csi2dc, CSI2DC_VPE, CSI2DC_VPE_ENABLE);
> > +	csi2dc_writel(csi2dc, CSI2DC_PU, CSI2DC_PU_VP);
> > +}
> > +
> > +static inline struct csi2dc_device *
> > +csi2dc_sd_to_csi2dc_device(struct v4l2_subdev *csi2dc_sd)
> > +{
> > +	return container_of(csi2dc_sd, struct csi2dc_device, csi2dc_sd);
> > +}
> > +
> > +static int csi2dc_enum_mbus_code(struct v4l2_subdev *csi2dc_sd,
> > +				 struct v4l2_subdev_pad_config *cfg,
> > +				 struct v4l2_subdev_mbus_code_enum *code)
> > +{
> > +	struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
> > +
> > +	if (code->index >= csi2dc->num_fmts)
> > +		return -EINVAL;
> > +
> > +	code->code = csi2dc->formats[code->index]->mbus_code;
> > +	return 0;
> > +}
> > +
> > +static int csi2dc_set_fmt(struct v4l2_subdev *csi2dc_sd,
> > +			  struct v4l2_subdev_pad_config *cfg,
> > +			  struct v4l2_subdev_format *req_fmt)
> > +{
> > +	struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
> > +	struct csi2dc_format *fmt;
> > +	int ret, i;
> > +
> > +	if (!csi2dc->completed) {
> > +		dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
> > +		return 0;
> > +	}
> > +
> > +	for (fmt = csi2dc->formats[0], i = 0; i < csi2dc->num_fmts; fmt++, i++)
> > +		if (req_fmt->format.code == fmt->mbus_code)
> > +			csi2dc->try_fmt = fmt;
> > +
> > +	/* in case we could not find the desired format, default to something */
> > +	if (!csi2dc->try_fmt  ||
> > +	    req_fmt->format.code != csi2dc->try_fmt->mbus_code) {
> > +		csi2dc->try_fmt = csi2dc->formats[0];
> > +
> > +		dev_dbg(csi2dc->dev,
> > +			"CSI2DC unsupported format 0x%x, defaulting to 0x%x\n",
> > +			req_fmt->format.code, csi2dc->formats[0]->mbus_code);
> > +
> > +		req_fmt->format.code = csi2dc->formats[0]->mbus_code;
> > +	}
> > +
> > +	/* if we are just trying, we are done */
> > +	if (req_fmt->which == V4L2_SUBDEV_FORMAT_TRY)
> > +		return 0;
> > +
> > +	ret = v4l2_subdev_call(csi2dc->input_sd, pad, set_fmt, cfg, req_fmt);
> > +	if (ret) {
> > +		dev_err(csi2dc->dev, "input subdev failed %d\n", ret);
> > +		return ret;
> > +	}
> > +
> > +	csi2dc->cur_fmt = csi2dc->try_fmt;
> > +	/* update video pipe */
> > +	csi2dc_vp_update(csi2dc);
> > +
> > +	dev_dbg(csi2dc->dev, "CSI2DC new format: 0x%x\n", req_fmt->format.code);
> > +	return 0;
> > +}
> > +
> > +static int csi2dc_formats_init(struct csi2dc_device *csi2dc)
> > +{
> > +	struct csi2dc_format *fmt;
> > +	struct v4l2_subdev *subdev = csi2dc->input_sd;
> > +	unsigned int num_fmts, i;
> > +
> > +	struct v4l2_subdev_mbus_code_enum mbus_code = {
> > +		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
> > +		.index = 0,
> > +	};
> > +
> > +	num_fmts = 0;
> > +
> > +	csi2dc->formats = devm_kcalloc(csi2dc->dev,
> > +				       ARRAY_SIZE(csi2dc_formats_list),
> > +				       sizeof(*csi2dc->formats), GFP_KERNEL);
> > +	if (!csi2dc->formats)
> > +		return -ENOMEM;
> > +
> > +	while (!v4l2_subdev_call(subdev, pad, enum_mbus_code, NULL,
> > +	       &mbus_code)) {
> > +		mbus_code.index++;
> > +		for (fmt = &csi2dc_formats_list[0], i = 0;
> > +		     i < ARRAY_SIZE(csi2dc_formats_list); i++, fmt++)
> > +			if (fmt->mbus_code == mbus_code.code) {
> > +				csi2dc->formats[num_fmts] = fmt;
> > +				num_fmts++;
> > +			}
> > +	}
> 
> For the reasons explained above and by Sakari, I think this should be dropped
> 
> > +
> > +	if (!num_fmts)
> > +		return -ENXIO;
> > +
> > +	csi2dc->num_fmts = num_fmts;
> > +
> > +	return 0;
> > +}
> > +
> > +static int csi2dc_power(struct csi2dc_device *csi2dc, int on)
> > +{
> > +	int ret = 0;
> > +
> > +	if (!csi2dc->completed) {
> > +		dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
> > +		return 0;
> > +	}
> 
> Can this happen ?
> 
> > +
> > +	if (csi2dc->powered_on == on)
> > +		return 0;
> 
> Same question
> 
> > +
> > +	if (on)
> > +		ret = clk_prepare_enable(csi2dc->scck);
> > +	else
> > +		clk_disable_unprepare(csi2dc->scck);
> > +	if (ret)
> > +		dev_err(csi2dc->dev, "failed to enable scck: %d\n", ret);
> > +
> > +	/* if powering up, deassert reset line */
> > +	if (on)
> > +		csi2dc_writel(csi2dc, CSI2DC_GCTLR, CSI2DC_GCTLR_SWRST);
> > +
> > +	/* if powering down, assert reset line */
> > +	if (!on)
> > +		csi2dc_writel(csi2dc, CSI2DC_GCTLR, !CSI2DC_GCTLR_SWRST);
> > +	if (!ret)
> > +		csi2dc->powered_on = on;
> 
> Wouldn't this be better coded as
> 
>         if (on) {
>                 clk_prepare_enable
>                 csi2dc_writel(SWRST)
>                 powered_on = true
>         } else {
>                 clk_disable_unrepare
>                 csi2dc_writel(!SWRST)
>                 powered_on = false
>         }
> > +
> > +	return ret;
> > +}
> > +
> > +static int csi2dc_s_stream(struct v4l2_subdev *csi2dc_sd, int enable)
> > +{
> > +	struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
> > +
> > +	if (!csi2dc->completed) {
> > +		dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
> > +		return 0;
> > +	}
> > +
> > +	return v4l2_subdev_call(csi2dc->input_sd, video, s_stream, enable);
> > +}
> > +
> > +static int csi2dc_g_frame_interval(struct v4l2_subdev *csi2dc_sd,
> > +				   struct v4l2_subdev_frame_interval *interval)
> > +{
> > +	struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
> > +
> > +	if (!csi2dc->completed) {
> > +		dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
> > +		return 0;
> > +	}
> > +
> > +	return v4l2_subdev_call(csi2dc->input_sd, video, g_frame_interval,
> > +				interval);
> > +}
> > +
> > +static int csi2dc_s_frame_interval(struct v4l2_subdev *csi2dc_sd,
> > +				   struct v4l2_subdev_frame_interval *interval)
> > +{
> > +	struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
> > +
> > +	if (!csi2dc->completed) {
> > +		dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
> > +		return 0;
> > +	}
> > +
> > +	return v4l2_subdev_call(csi2dc->input_sd, video, s_frame_interval,
> > +				interval);
> > +}
> > +
> > +static int csi2dc_enum_frame_size(struct v4l2_subdev *csi2dc_sd,
> > +				  struct v4l2_subdev_pad_config *cfg,
> > +				  struct v4l2_subdev_frame_size_enum *fse)
> > +{
> > +	struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
> > +
> > +	if (!csi2dc->completed) {
> > +		dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
> > +		return 0;
> > +	}
> > +
> > +	return v4l2_subdev_call(csi2dc->input_sd, pad, enum_frame_size, cfg,
> > +				fse);
> > +}
> > +
> > +static int csi2dc_enum_frame_interval(struct v4l2_subdev *csi2dc_sd,
> > +			      struct v4l2_subdev_pad_config *cfg,
> > +			      struct v4l2_subdev_frame_interval_enum *fie)
> > +{
> > +	struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
> > +
> > +	if (!csi2dc->completed) {
> > +		dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
> > +		return 0;
> > +	}
> > +
> > +	return v4l2_subdev_call(csi2dc->input_sd, pad, enum_frame_interval, cfg,
> > +				fie);
> > +}
> > +
> > +static const struct v4l2_subdev_pad_ops csi2dc_pad_ops = {
> > +	.enum_mbus_code = csi2dc_enum_mbus_code,
> > +	.set_fmt = csi2dc_set_fmt,
> > +	.enum_frame_size = csi2dc_enum_frame_size,
> > +	.enum_frame_interval = csi2dc_enum_frame_interval,
> > +};
> > +
> > +static const struct v4l2_subdev_video_ops csi2dc_video_ops = {
> > +	.s_stream = csi2dc_s_stream,
> > +	.g_frame_interval = csi2dc_g_frame_interval,
> > +	.s_frame_interval = csi2dc_s_frame_interval,
> > +};
> > +
> > +static const struct v4l2_subdev_ops csi2dc_subdev_ops = {
> > +	.pad = &csi2dc_pad_ops,
> > +	.video = &csi2dc_video_ops,
> > +};
> > +
> > +static int csi2dc_get_mbus_config(struct csi2dc_device *csi2dc)
> > +{
> > +	struct v4l2_mbus_config mbus_config = { 0 };
> > +	int ret;
> > +
> > +	ret = v4l2_subdev_call(csi2dc->input_sd, pad, get_mbus_config,
> > +			       csi2dc->remote_pad, &mbus_config);
> > +	if (ret == -ENOIOCTLCMD) {
> > +		dev_dbg(csi2dc->dev,
> > +			"no remote mbus configuration available\n");
> > +		goto csi2dc_get_mbus_config_defaults;
> > +	}
> > +
> > +	if (ret) {
> > +		dev_err(csi2dc->dev,
> > +			"failed to get remote mbus configuration\n");
> > +		goto csi2dc_get_mbus_config_defaults;
> 
> This should probably be an error reported to the caller. But this
> function return value is not checked, so it's probably fine.
> 
> > +	}
> > +
> > +	if (mbus_config.flags & V4L2_MBUS_CSI2_CHANNEL_0)
> > +		csi2dc->vc = 0;
> > +	else if (mbus_config.flags & V4L2_MBUS_CSI2_CHANNEL_1)
> > +		csi2dc->vc = 1;
> > +	else if (mbus_config.flags & V4L2_MBUS_CSI2_CHANNEL_2)
> > +		csi2dc->vc = 2;
> > +	else if (mbus_config.flags & V4L2_MBUS_CSI2_CHANNEL_3)
> > +		csi2dc->vc = 3;
> > +
> > +	dev_dbg(csi2dc->dev, "subdev sending on channel %d\n", csi2dc->vc);
> > +
> > +	csi2dc->clk_gated = mbus_config.flags &
> > +			    V4L2_MBUS_CSI2_NONCONTINUOUS_CLOCK;
> > +
> > +	dev_dbg(csi2dc->dev, "%s clock\n",
> > +		csi2dc->clk_gated ? "gated" : "free running");
> > +
> > +	return 0;
> > +
> > +csi2dc_get_mbus_config_defaults:
> > +	csi2dc->vc = 0; /* Virtual ID 0 by default */
> > +	csi2dc->clk_gated = false; /* Free running clock by default */
> > +
> > +	return 0;
> > +}
> > +
> > +static int csi2dc_async_bound(struct v4l2_async_notifier *notifier,
> > +			      struct v4l2_subdev *subdev,
> > +			      struct v4l2_async_subdev *asd)
> > +{
> > +	struct csi2dc_device *csi2dc = container_of(notifier->v4l2_dev,
> > +					struct csi2dc_device, v4l2_dev);
> > +	int pad;
> > +
> > +	csi2dc->input_sd = subdev;
> > +
> > +	pad = media_entity_get_fwnode_pad(&subdev->entity,
> > +					  asd->match.fwnode,
> > +					  MEDIA_PAD_FL_SOURCE);
> > +	if (pad < 0) {
> > +		dev_err(csi2dc->dev, "Failed to find pad for %s\n",
> > +			subdev->name);
> > +		return pad;
> > +	}
> > +
> > +	csi2dc->remote_pad = pad;
> > +
> > +	csi2dc_get_mbus_config(csi2dc);
> 
> The closer to s_stream you call get_mbus_config, the less the chances
> of receiving a stale configuration, if this can happen.
> 
> > +
> > +	return 0;
> > +}
> > +
> > +static int csi2dc_async_complete(struct v4l2_async_notifier *notifier)
> > +{
> > +	struct csi2dc_device *csi2dc =
> > +		container_of(notifier->v4l2_dev, struct csi2dc_device,
> > +			     v4l2_dev);
> > +	int ret;
> > +
> > +	ret = csi2dc_formats_init(csi2dc);
> > +	if (ret)
> > +		return ret;
> > +
> > +	ret = v4l2_device_register_subdev_nodes(&csi2dc->v4l2_dev);
> > +	if (ret < 0) {
> > +		v4l2_err(&csi2dc->v4l2_dev,
> > +			 "failed to register subdev nodes\n");
> > +		return ret;
> > +	}
> > +
> > +	csi2dc->completed = true;
> > +
> > +	csi2dc_writel(csi2dc, CSI2DC_GCFG,
> > +		      (SAMA7G5_HLC & CSI2DC_GCFG_HLC_MASK) |
> > +		      (csi2dc->clk_gated ? 0 : CSI2DC_GCFG_MIPIFRN));
> > +
> > +	csi2dc_writel(csi2dc, CSI2DC_VPCOL,
> > +		      CSI2DC_VPCOL_COL(0xFFF) & CSI2DC_VPCOL_COL_MASK);
> > +	csi2dc_writel(csi2dc, CSI2DC_VPROW,
> > +		      CSI2DC_VPROW_ROW(0xFFF) & CSI2DC_VPROW_ROW_MASK);
> > +
> > +	/* once we are completed, we can register ourselves in the pipeline */
> > +	schedule_work(&csi2dc->workq);
> > +
> > +	return ret;
> > +}
> > +
> > +static const struct v4l2_async_notifier_operations csi2dc_async_ops = {
> > +	.bound = csi2dc_async_bound,
> > +	.complete = csi2dc_async_complete,
> > +};
> > +
> > +static void csi2dc_cleanup_notifier(struct csi2dc_device *csi2dc)
> > +{
> > +	v4l2_async_notifier_unregister(&csi2dc->notifier);
> > +	v4l2_async_notifier_cleanup(&csi2dc->notifier);
> > +}
> > +
> > +static int csi2dc_prepare_notifier(struct csi2dc_device *csi2dc,
> > +				   struct device_node *input_parent)
> > +{
> > +	int ret;
> > +
> > +	v4l2_async_notifier_init(&csi2dc->notifier);
> > +
> > +	csi2dc->asd = kzalloc(sizeof(*csi2dc->asd), GFP_KERNEL);
> > +	if (!csi2dc->asd)
> > +		return -ENOMEM;
> > +
> > +	csi2dc->asd->match_type = V4L2_ASYNC_MATCH_FWNODE;
> > +	csi2dc->asd->match.fwnode = of_fwnode_handle(input_parent);
> 
> If you use v4l2_async_notifier_add_fwnode_subdev() the framework does
> this for you.
> 
> > +
> > +	ret = v4l2_async_notifier_add_subdev(&csi2dc->notifier, csi2dc->asd);
> > +	if (ret) {
> > +		dev_err(csi2dc->dev, "failed to add async notifier.\n");
> > +		v4l2_async_notifier_cleanup(&csi2dc->notifier);
> > +		goto csi2dc_prepare_notifier_err;
> > +	}
> > +
> > +	csi2dc->notifier.ops = &csi2dc_async_ops;
> > +
> > +	ret = v4l2_async_notifier_register(&csi2dc->v4l2_dev,
> > +					   &csi2dc->notifier);
> > +
> > +	if (ret) {
> > +		dev_err(csi2dc->dev, "fail to register async notifier.\n");
> 
> Shouldn't you cleanup the notifier if registration fails ?
> 
> > +		goto csi2dc_prepare_notifier_err;
> > +	}
> > +
> > +csi2dc_prepare_notifier_err:
> > +	of_node_put(input_parent);
> > +
> > +	return ret;
> > +}
> > +
> > +static int csi2dc_of_parse(struct csi2dc_device *csi2dc,
> > +			   struct device_node *of_node)
> > +{
> > +	struct device_node *input_node, *sink_node, *input_parent;
> > +	struct v4l2_fwnode_endpoint input_endpoint = { 0 },
> > +				    sink_endpoint = { 0 };
> > +	int ret;
> > +
> > +	input_node = of_graph_get_next_endpoint(of_node, NULL);
> > +
> > +	if (!input_node) {
> > +		dev_err(csi2dc->dev,
> > +			"missing port node at %s, input node is mandatory.\n",
> 
> Please use %pOF to print the node name
> Also, input_node should be put in the error path
> 
> > +			of_node->full_name);
> > +		return -EINVAL;
> > +	}
> > +
> > +	ret = v4l2_fwnode_endpoint_parse(of_fwnode_handle(input_node),
> > +					 &input_endpoint);
> 
> Please set input_endpoint.bus_type if you know what kind of bus you're
> dealing with (not having the bindings of the IDI transmitter I'm not
> sure. Is this V4L2_MBUS_CSI2_DPHY ?)
> 
> > +
> > +	if (ret) {
> > +		dev_err(csi2dc->dev, "endpoint not defined at %s\n",
> > +			of_node->full_name);
> > +		return ret;
> > +	}
> > +
> > +	input_parent = of_graph_get_remote_port_parent(input_node);
> > +	if (!input_parent) {
> 
> Missing of_node_put(input_node)
> 
> > +		dev_err(csi2dc->dev,
> > +			"could not get input node's parent node.\n");
> > +		return -EINVAL;
> > +	}
> > +
> > +	sink_node = of_graph_get_next_endpoint(of_node, input_node);
> > +
> > +	if (sink_node)
> > +		ret = v4l2_fwnode_endpoint_parse(of_fwnode_handle(sink_node),
> > +						 &sink_endpoint);
> 
> Same, set sink_endpoint.bus_type if you know it's MBUS_PARALLEL
> 
> > +
> > +	if (!sink_node || ret) {
> 
> If parsing fail you don't return an error but continue registering the
> notifier and potentially end up registering the async subdev for this
> entity even if the endpoint parsing failed.
> 
> > +		dev_info(csi2dc->dev,
> > +			 "missing sink node at %s, data pipe available only.\n",
> > +			 of_node->full_name);
> > +	} else {
> > +		csi2dc->video_pipe = true;
> 
> video_pipe is unused it seems
> 
> > +
> > +		dev_dbg(csi2dc->dev, "block %s %d.%d->%d.%d video pipeline\n",
> > +			of_node->full_name, input_endpoint.base.port,
> > +			input_endpoint.base.id,	sink_endpoint.base.port,
> > +			sink_endpoint.base.id);
> > +	}
> > +
> > +	of_node_put(sink_node);
> > +	of_node_put(input_node);
> > +
> > +	/* prepare async notifier for subdevice completion */
> > +	return csi2dc_prepare_notifier(csi2dc, input_parent);
> > +}
> > +
> > +static void csi2dc_workq_handler(struct work_struct *workq)
> > +{
> > +	struct csi2dc_device *csi2dc = container_of(workq,
> > +					struct csi2dc_device, workq);
> > +	int ret;
> > +
> > +	if (v4l2_async_register_subdev(&csi2dc->csi2dc_sd))
> > +		dev_dbg(csi2dc->dev, "failed to register the subdevice\n");
> 
> That's peculiar, why do you have to schedule this to a workqueue
> instead of doing this in the complete() callback ?
> 
> > +
> > +	ret = csi2dc_power(csi2dc, true);
> > +	if (ret < 0)
> > +		v4l2_err(&csi2dc->v4l2_dev, "failed to power on\n");
> 
> Should the device be powered on at s_stream time ? Possibly with a
> pm_runtime_get_sync() call ? I see you register pm_runtime operations,
> but never call get_sync() or _put().
> 
> What if CONFIG_PM not selected ? Should this driver select it ? Do you
> have use cases where that's not possible ?
> 
> > +}
> > +
> > +static int csi2dc_probe(struct platform_device *pdev)
> > +{
> > +	struct device *dev = &pdev->dev;
> > +	struct csi2dc_device *csi2dc;
> > +	struct resource *res = NULL;
> > +	int ret = 0;
> > +
> > +	csi2dc = devm_kzalloc(dev, sizeof(*csi2dc), GFP_KERNEL);
> > +	if (!csi2dc)
> > +		return -ENOMEM;
> > +
> > +	csi2dc->dev = dev;
> > +
> > +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > +	if (!res)
> > +		return -EINVAL;
> 
> devm_ioremap_resource() checks for the validity of 'res' so you can
> drop the previous two lines
> 
> > +
> > +	csi2dc->base = devm_ioremap_resource(dev, res);
> > +
> 
> Is the empy line intentional, sometimes you have one, sometimes you
> don't ?
> 
> > +	if (IS_ERR(csi2dc->base)) {
> > +		dev_err(dev, "base address not set\n");
> 
> 
> > +		return PTR_ERR(csi2dc->base);
> > +	}
> > +
> > +	csi2dc->pclk = devm_clk_get(dev, "pclk");
> > +	if (IS_ERR(csi2dc->pclk)) {
> > +		ret = PTR_ERR(csi2dc->pclk);
> > +		dev_err(dev, "failed to get pclk: %d\n", ret);
> > +		return ret;
> 
> Just return PTR_ERR instead of assigning to ret
> 
> > +	}
> > +
> > +	ret = clk_prepare_enable(csi2dc->pclk);
> > +	if (ret) {
> > +		dev_err(dev, "failed to enable pclk: %d\n", ret);
> > +		return ret;
> > +	}
> 
> Has this clock to be enabled here or can it be done in the
> pm_runtime callback ?
> 
> > +
> > +	csi2dc->scck = devm_clk_get(dev, "scck");
> > +	if (IS_ERR(csi2dc->scck)) {
> > +		ret = PTR_ERR(csi2dc->scck);
> > +		dev_err(dev, "failed to get scck: %d\n", ret);
> > +		goto csi2dc_clk_fail;
> > +	}
> > +
> > +	ret = v4l2_device_register(dev, &csi2dc->v4l2_dev);
> > +	if (ret) {
> > +		dev_err(dev, "unable to register v4l2 device.\n");
> > +		goto csi2dc_clk_fail;
> > +	}
> > +
> > +	v4l2_subdev_init(&csi2dc->csi2dc_sd, &csi2dc_subdev_ops);
> > +
> > +	csi2dc->csi2dc_sd.owner = THIS_MODULE;
> > +	csi2dc->csi2dc_sd.dev = dev;
> > +	snprintf(csi2dc->csi2dc_sd.name, sizeof(csi2dc->csi2dc_sd.name),
> > +		 "CSI2DC.0");
> > +
> > +	csi2dc->csi2dc_sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
> > +	csi2dc->csi2dc_sd.entity.function = MEDIA_ENT_F_VID_IF_BRIDGE;
> > +	csi2dc->pads[CSI2DC_PAD_SINK].flags = MEDIA_PAD_FL_SINK;
> > +	csi2dc->pads[CSI2DC_PAD_SOURCE].flags = MEDIA_PAD_FL_SOURCE;
> 
> Isn't the source pad presence conditional to the presence of
> port@1 ?
> 
> > +
> > +	ret = media_entity_pads_init(&csi2dc->csi2dc_sd.entity, CSI2DC_PADS_NUM,
> > +				     csi2dc->pads);
> > +	if (ret < 0) {
> > +		dev_err(dev, "media entity init failed\n");
> > +		goto csi2dc_probe_entity_err;
> > +	}
> > +
> > +	v4l2_set_subdevdata(&csi2dc->csi2dc_sd, pdev);
> > +
> > +	platform_set_drvdata(pdev, &csi2dc->csi2dc_sd);
> > +
> > +	INIT_WORK(&csi2dc->workq, csi2dc_workq_handler);
> > +
> > +	ret = csi2dc_of_parse(csi2dc, dev->of_node);
> > +	if (ret)
> > +		goto csi2dc_probe_entity_err;
> > +
> > +	dev_info(dev, "Microchip CSI2DC version %x\n",
> > +		 csi2dc_readl(csi2dc, CSI2DC_VERSION));
> > +
> > +	pm_runtime_set_active(dev);
> > +	pm_runtime_enable(dev);
> > +	pm_request_idle(dev);
> > +
> > +	return 0;
> > +
> > +csi2dc_probe_entity_err:
> > +	media_entity_cleanup(&csi2dc->csi2dc_sd.entity);
> > +	v4l2_device_unregister(&csi2dc->v4l2_dev);
> > +csi2dc_clk_fail:
> > +	clk_disable_unprepare(csi2dc->pclk);
> > +	return ret;
> > +}
> > +
> > +static int csi2dc_remove(struct platform_device *pdev)
> > +{
> > +	struct v4l2_subdev *csi2dc_sd = platform_get_drvdata(pdev);
> > +	struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
> > +
> > +	pm_runtime_disable(&pdev->dev);
> > +
> > +	v4l2_async_unregister_subdev(&csi2dc->csi2dc_sd);
> > +	csi2dc_cleanup_notifier(csi2dc);
> > +	media_entity_cleanup(&csi2dc->csi2dc_sd.entity);
> > +	v4l2_device_unregister(&csi2dc->v4l2_dev);
> > +	clk_disable_unprepare(csi2dc->pclk);
> > +
> > +	return 0;
> > +}
> > +
> > +static int __maybe_unused csi2dc_runtime_suspend(struct device *dev)
> > +{
> > +	struct csi2dc_device *csi2dc = dev_get_drvdata(dev);
> > +
> > +	return csi2dc_power(csi2dc, false);
> > +}
> > +
> > +static int __maybe_unused csi2dc_runtime_resume(struct device *dev)
> > +{
> > +	struct csi2dc_device *csi2dc = dev_get_drvdata(dev);
> > +
> > +	return csi2dc_power(csi2dc, true);
> > +}
> > +
> > +static const struct dev_pm_ops csi2dc_dev_pm_ops = {
> > +	SET_RUNTIME_PM_OPS(csi2dc_runtime_suspend, csi2dc_runtime_resume, NULL)
> > +};
> > +
> > +static const struct of_device_id csi2dc_of_match[] = {
> > +	{ .compatible = "microchip,sama7g5-csi2dc" },
> > +	{ }
> > +};
> > +
> > +MODULE_DEVICE_TABLE(of, csi2dc_of_match);
> > +
> > +static struct platform_driver csi2dc_driver = {
> > +	.probe	= csi2dc_probe,
> > +	.remove	= csi2dc_remove,
> > +	.driver	= {
> > +		.name		= "microchip-csi2dc",
> > +		.pm		= &csi2dc_dev_pm_ops,
> > +		.of_match_table = of_match_ptr(csi2dc_of_match),
> > +	},
> > +};
> > +
> > +module_platform_driver(csi2dc_driver);
> > +
> > +MODULE_AUTHOR("Eugen Hristev <eugen.hristev@microchip.com>");
> > +MODULE_DESCRIPTION("Microchip CSI2 Demux Controller driver");
> > +MODULE_LICENSE("GPL v2");
> > +MODULE_SUPPORTED_DEVICE("video");
> 
> For my education, what's MODULE_SUPPORTED_DEVICE for ?

It's "not yet implemented" since 2005, I think it can be dropped :-)

-- 
Regards,

Laurent Pinchart

Re: [PATCH v5 2/3] media: atmel: introduce microchip csi2dc driver

[Eugen.Hristev]

On 17.11.2020 14:09, Laurent Pinchart wrote:
> Hello everybody,
> 
> On Tue, Nov 17, 2020 at 12:59:02PM +0100, Jacopo Mondi wrote:
>> On Thu, Nov 12, 2020 at 03:34:36PM +0200, Eugen Hristev wrote:
>>> Microchip CSI2DC (CSI2 Demultiplexer Controller) is a misc bridge device
>>> that converts a byte stream in IDI Synopsys format (coming from a CSI2HOST)
>>> to a pixel stream that can be captured by a sensor controller.
>>>
>>> Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
>>> ---
>>> Hello,
>>>
>>> There still are some open questions regarding the last reviews on the ML.
>>>
>>> Regarding the format list which is not const, I cannot have it const because
>>> I reference elements from this list into a dynamic list which is non-const.
>>>
>>> Regarding the presence of the v4l2_dev, without this I cannot add a notifier
>>> for this device to have it async completed , when the underlying subdevice
>>> finishes probing.
>>
>> I see you have a discussion with Sakari on-going on this, and I have
>> the very same comment he had.
>>
>> Should a sub-notifier be used and this driver should not register any
>> v4l2_dev but integrate in the media graph of the receiver ?
>>
>> For reference, rcar-csi2 uses sub-notifiers and register in the
>> rcar-vin media graph, it doesn't need to set up a v4l2_dev.
>>
>> rcar-vin (the DMA engine driver) that register video nodes and the v4l2-dev
>> also registers the device nodes for all the connected subdevices.
> 
> Sub-notifiers were invited for this purpose, so I think they're the
> right tool.
> 
>>> Regarding the callbacks for set frame interval, set frame size, etc, I cannot
>>> remove them because losing functionality to the underlying subdevice, as
>>> explained in :
>>> https://lkml.org/lkml/2020/10/12/427
>>
>> Using the frame sizes as in the example you reported, if this device has
>> limitations on the supported sizes, (a min and a max most
>> probably) that's the only thing that should be exposed from this
>> driver subdevice. The sensor subdevice instead will report the
>> available discrete sizes and userspace configures the sensor's source
>> pad and the bridge's sink pad with the same sizes to properly set up the
>> capture pipeline. video0 should not report the sizes exposed by the sensor
>> nor any information that depends on what's connected to it.
> 
> Agreed. Subdev drivers should remain simple and cover only the subdev
> they manage. Bundling it together is the job of userspace. In the legacy
> model it uses to be the job of the top-level V4L2 driver (the one
> implementing v4l2_device), but that's legacy, especially for embedded
> camera use cases. In any case, the top-level logic must not be spread
> across subdevices.
> 
>> I know what your next question is: what about existing application
>> that only know about video0 and want to setup everything from there. I
>> understand vendors not wanting to wrap gstreamer or what is used in
>> the wild in custom scripts that sets up the pipeline opportunely
>> before streaming, and I'm pretty sure you know what is the solution I
>> would propose for this :)
>>
>> I've just gone through the same path with RPi's Unicam, that does the
>> same thing as your one does: it's an MC driver, but wants to control
>> the sensor through the v4l2-subdev kAPI to support legacy use cases
>> not covered by libcamera. The fact is that we're stuck in this limbo
>> where MC pipeline tries to decouple components one from each other and
>> delegate their configuration to userspace, but at the same time
>> vendors want to be able to use the simple plain video node centric
>> interface because of their existing user base, so I understand your
>> discomfort, but the 'simple plain' approach is what's preventing Linux
>> platforms to be in-par with proprietary and custom solutions for any
>> use case that is not a simple frame capture, so I think it's fair for
>> mainline to push for this evolution to happen. Just my2c of course.
> 
> Compatibility with the userspace of downstream kernels is important, but
> that's a downstream kernel issue. In mainline we want to go the MC way,
> and downstream can then, if desired, implement the configuration of the
> pipeline in the top-level V4L2 driver in the kernel to support the
> existing userbase. For new drivers I wouldn't recommend that, for
> existing downstream drivers it may be required.

Hello,

First of all thank you for the review and explanations.

I am still confused about how does the userspace know which elements are 
in the pipeline and how to connect them ?
And if this is the case, what is the purpose of the endpoints in the DT ?

At this moment, I just use the /dev/video0, because the top v4l2 driver 
configures the subdevice, and this subdevice configures it's own 
subdevice and so on, until the sensor itself.

My top v4l2 driver will not 'complete' unless a subdevice registers 
itself , and if this subdevice does not provide any information 
regarding its formats, the probe of the top v4l2 driver will fail, 
because it will not find compatibility between it's supported input 
formats and what the subdevice provides.

So what to do in this case ? Libcamera will configure this whole 
pipeline for me , if the drivers just probe ( and start/stop streaming 
by selecting the respective registers) ? or how to do this whole 
pipeline configuration ?


> 
>> Some more comments on the implementation below
>>
>>> Changes in v5:
>>> - only in bindings
>>>
>>> Changes in v4:
>>> - now using get_mbus_config ops to get data from the subdevice, like the
>>> virtual channel id, and the clock type.
>>> - now having possibility to select any of the RAW10 data modes
>>> - at completion time, select which formats are also available in the subdevice,
>>> and move to the dynamic list accordingly
>>> - changed the pipeline integration, do not advertise subdev ready at probe time.
>>> wait until completion is done, and then start a workqueue that will register
>>> this device as a subdevice for the next element in pipeline.
>>> - moved the s_power code into a different function called now csi2dc_power
>>> that is called with CONFIG_PM functions. This is also called at completion,
>>> to have the device ready in case CONFIG_PM is not selected on the platform.
>>> - merged try_fmt into set_fmt
>>> - driver cleanup, wrapped lines over 80 characters
>>>
>>> Changes in v2:
>>> - moved driver to platform/atmel
>>> - fixed minor things as per Sakari's review
>>> - still some things from v2 review are not yet addressed, to be followed up
>>>
>>>   drivers/media/platform/atmel/Kconfig          |  13 +
>>>   drivers/media/platform/atmel/Makefile         |   1 +
>>>   .../media/platform/atmel/microchip-csi2dc.c   | 785 ++++++++++++++++++
>>>   3 files changed, 799 insertions(+)
>>>   create mode 100644 drivers/media/platform/atmel/microchip-csi2dc.c
>>>
>>> diff --git a/drivers/media/platform/atmel/Kconfig b/drivers/media/platform/atmel/Kconfig
>>> index 99b51213f871..147e1c14129b 100644
>>> --- a/drivers/media/platform/atmel/Kconfig
>>> +++ b/drivers/media/platform/atmel/Kconfig
>>> @@ -32,3 +32,16 @@ config VIDEO_ATMEL_ISI
>>>      help
>>>        This module makes the ATMEL Image Sensor Interface available
>>>        as a v4l2 device.
>>> +
>>> +config VIDEO_MICROCHIP_CSI2DC
>>> +   tristate "Microchip CSI2 Demux Controller"
>>> +   depends on VIDEO_V4L2 && COMMON_CLK && OF
>>> +   depends on ARCH_AT91 || COMPILE_TEST
>>> +   select MEDIA_CONTROLLER
>>> +   select VIDEO_V4L2_SUBDEV_API
>>> +   select V4L2_FWNODE
>>> +   help
>>> +     CSI2 Demux Controller driver. CSI2DC is a helper chip
>>> +     that converts IDI interface byte stream to a parallel pixel stream.
>>> +     It supports various RAW formats as input.
>>> +     Performs clock domain crossing between hardware blocks.
>>
>> Is the last phrase necessary ? Also missing the usual
>>
>>          To compile this driver as a module, choose M here: the
>>          module will be called ...
>>
>>> diff --git a/drivers/media/platform/atmel/Makefile b/drivers/media/platform/atmel/Makefile
>>> index c5c01556c653..8e80af500bf5 100644
>>> --- a/drivers/media/platform/atmel/Makefile
>>> +++ b/drivers/media/platform/atmel/Makefile
>>> @@ -5,3 +5,4 @@ atmel-xisc-objs = atmel-sama7g5-isc.o atmel-isc-base.o
>>>   obj-$(CONFIG_VIDEO_ATMEL_ISI) += atmel-isi.o
>>>   obj-$(CONFIG_VIDEO_ATMEL_ISC) += atmel-isc.o
>>>   obj-$(CONFIG_VIDEO_ATMEL_XISC) += atmel-xisc.o
>>> +obj-$(CONFIG_VIDEO_MICROCHIP_CSI2DC) += microchip-csi2dc.o
>>> diff --git a/drivers/media/platform/atmel/microchip-csi2dc.c b/drivers/media/platform/atmel/microchip-csi2dc.c
>>> new file mode 100644
>>> index 000000000000..fda1d5882dbb
>>> --- /dev/null
>>> +++ b/drivers/media/platform/atmel/microchip-csi2dc.c
>>> @@ -0,0 +1,785 @@
>>> +// SPDX-License-Identifier: GPL-2.0
>>
>> Nit: I see GPL-2.0 listed as deprecated by spdx.org
>> Should you use one of:
>>                GPL-2.0-only
>>                        GPL-2.0-or-later
>>
>>> +/*
>>> + * Microchip CSI2 Demux Controller (CSI2DC) driver
>>> + *
>>> + * Copyright (C) 2018-2020 Microchip Technology, Inc.
>>> + *
>>> + * Author: Eugen Hristev <eugen.hristev@microchip.com>
>>> + *
>>> + */
>>> +
>>> +#include <linux/clk.h>
>>> +#include <linux/module.h>
>>> +#include <linux/of.h>
>>> +#include <linux/of_graph.h>
>>> +#include <linux/platform_device.h>
>>> +#include <linux/pm_runtime.h>
>>> +#include <linux/videodev2.h>
>>> +
>>> +#include <media/v4l2-device.h>
>>> +#include <media/v4l2-fwnode.h>
>>> +#include <media/v4l2-subdev.h>
>>> +#include <media/videobuf2-dma-contig.h>
>>> +
>>> +/* Global configuration register */
>>> +#define CSI2DC_GCFG                        0x0
>>> +
>>> +/* MIPI sensor pixel clock is free running */
>>> +#define CSI2DC_GCFG_MIPIFRN                BIT(0)
>>> +/* Output waveform inter-line minimum delay */
>>> +#define CSI2DC_GCFG_HLC(v)         ((v) << 4)
>>> +#define CSI2DC_GCFG_HLC_MASK               GENMASK(7, 4)
>>> +/* SAMA7G5 requires a HLC delay of 15 */
>>> +#define SAMA7G5_HLC                        (15)
>>> +
>>> +/* Global control register */
>>> +#define CSI2DC_GCTLR                       0x04
>>> +#define CSI2DC_GCTLR_SWRST         BIT(0)
>>> +
>>> +/* Global status register */
>>> +#define CSI2DC_GS                  0x08
>>> +
>>> +/* SSP interrupt status register */
>>> +#define CSI2DC_SSPIS                       0x28
>>> +/* Pipe update register */
>>> +#define CSI2DC_PU                  0xC0
>>> +/* Video pipe attributes update */
>>> +#define CSI2DC_PU_VP                       BIT(0)
>>> +
>>> +/* Pipe update status register */
>>> +#define CSI2DC_PUS                 0xC4
>>> +
>>> +/* Video pipeline enable register */
>>> +#define CSI2DC_VPE                 0xF8
>>> +#define CSI2DC_VPE_ENABLE          BIT(0)
>>> +
>>> +/* Video pipeline configuration register */
>>> +#define CSI2DC_VPCFG                       0xFC
>>> +/* Data type */
>>> +#define CSI2DC_VPCFG_DT(v)         ((v) << 0)
>>> +#define CSI2DC_VPCFG_DT_MASK               GENMASK(5, 0)
>>> +/* Virtual channel identifier */
>>> +#define CSI2DC_VPCFG_VC(v)         ((v) << 6)
>>> +#define CSI2DC_VPCFG_VC_MASK               GENMASK(7, 6)
>>> +/* Decompression enable */
>>> +#define CSI2DC_VPCFG_DE                    BIT(8)
>>> +/* Decoder mode */
>>> +#define CSI2DC_VPCFG_DM(v)         ((v) << 9)
>>> +#define CSI2DC_VPCFG_DM_DECODER8TO12       0
>>> +/* Decoder predictor 2 selection */
>>> +#define CSI2DC_VPCFG_DP2           BIT(12)
>>> +/* Recommended memory storage */
>>> +#define CSI2DC_VPCFG_RMS           BIT(13)
>>> +/* Post adjustment */
>>> +#define CSI2DC_VPCFG_PA                    BIT(14)
>>> +
>>> +/* Video pipeline column register */
>>> +#define CSI2DC_VPCOL                       0x100
>>> +/* Column number */
>>> +#define CSI2DC_VPCOL_COL(v)                ((v) << 0)
>>> +#define CSI2DC_VPCOL_COL_MASK              GENMASK(15, 0)
>>> +
>>> +/* Video pipeline row register */
>>> +#define CSI2DC_VPROW                       0x104
>>> +/* Row number */
>>> +#define CSI2DC_VPROW_ROW(v)                ((v) << 0)
>>> +#define CSI2DC_VPROW_ROW_MASK              GENMASK(15, 0)
>>> +
>>> +/* Version register */
>>> +#define CSI2DC_VERSION                     0x1FC
>>> +
>>> +/* register read/write helpers */
>>> +#define csi2dc_readl(st, reg)              readl_relaxed((st)->base + (reg))
>>> +#define csi2dc_writel(st, reg, val)        writel_relaxed((val), \
>>> +                                   (st)->base + (reg))
>>> +
>>> +/* supported RAW data types */
>>> +#define CSI2DC_DT_RAW6                     0x28
>>> +#define CSI2DC_DT_RAW7                     0x29
>>> +#define CSI2DC_DT_RAW8                     0x2A
>>> +#define CSI2DC_DT_RAW10                    0x2B
>>> +#define CSI2DC_DT_RAW12                    0x2C
>>> +#define CSI2DC_DT_RAW14                    0x2D
>>> +
>>> +struct csi2dc_format {
>>> +   u32                             mbus_code;
>>> +   u32                             dt;
>>> +};
>>> +
>>> +static struct csi2dc_format csi2dc_formats_list[] = {
>>> +   {
>>> +           .mbus_code =            MEDIA_BUS_FMT_SRGGB10_1X10,
>>> +           .dt =                   CSI2DC_DT_RAW10,
>>> +   }, {
>>> +           .mbus_code =            MEDIA_BUS_FMT_SBGGR10_1X10,
>>> +           .dt =                   CSI2DC_DT_RAW10,
>>> +   }, {
>>> +           .mbus_code =            MEDIA_BUS_FMT_SGRBG10_1X10,
>>> +           .dt =                   CSI2DC_DT_RAW10,
>>> +   }, {
>>> +           .mbus_code =            MEDIA_BUS_FMT_SGBRG10_1X10,
>>> +           .dt =                   CSI2DC_DT_RAW10,
>>> +   },
>>> +};
>>> +
>>> +enum mipi_csi_pads {
>>> +   CSI2DC_PAD_SINK                 = 0,
>>> +   CSI2DC_PAD_SOURCE               = 1,
>>> +   CSI2DC_PADS_NUM                 = 2,
>>> +};
>>> +
>>> +struct csi2dc_device {
>>> +   void __iomem                    *base;
>>> +   struct v4l2_subdev              csi2dc_sd;
>>> +   struct device                   *dev;
>>> +   struct v4l2_device              v4l2_dev;
>>> +   struct clk                      *pclk;
>>> +   struct clk                      *scck;
>>> +
>>> +   bool                            video_pipe;
>>> +
>>> +   u32                             num_fmts;
>>> +   struct csi2dc_format            **formats;
>>> +
>>> +   struct csi2dc_format            *cur_fmt;
>>> +   struct csi2dc_format            *try_fmt;
>>> +
>>> +   struct media_pad                pads[CSI2DC_PADS_NUM];
>>> +
>>> +   bool                            clk_gated;
>>> +   u32                             vc;
>>> +
>>> +   struct v4l2_async_subdev        *asd;
>>> +   struct v4l2_async_notifier      notifier;
>>> +
>>> +   struct v4l2_subdev              *input_sd;
>>> +
>>> +   u32                             remote_pad;
>>> +
>>> +   bool                            completed;
>>> +   bool                            powered_on;
>>> +
>>> +   struct work_struct              workq;
>>> +};
>>> +
>>> +static void csi2dc_vp_update(struct csi2dc_device *csi2dc)
>>> +{
>>> +   u32 vp;
>>> +
>>> +   vp = CSI2DC_VPCFG_DT(csi2dc->cur_fmt->dt) & CSI2DC_VPCFG_DT_MASK;
>>> +   vp |= CSI2DC_VPCFG_VC(csi2dc->vc) & CSI2DC_VPCFG_VC_MASK;
>>> +   vp &= ~CSI2DC_VPCFG_DE;
>>> +   vp |= CSI2DC_VPCFG_DM(CSI2DC_VPCFG_DM_DECODER8TO12);
>>> +   vp &= ~CSI2DC_VPCFG_DP2;
>>> +   vp &= ~CSI2DC_VPCFG_RMS;
>>> +   vp |= CSI2DC_VPCFG_PA;
>>> +
>>> +   csi2dc_writel(csi2dc, CSI2DC_VPCFG, vp);
>>> +   csi2dc_writel(csi2dc, CSI2DC_VPE, CSI2DC_VPE_ENABLE);
>>> +   csi2dc_writel(csi2dc, CSI2DC_PU, CSI2DC_PU_VP);
>>> +}
>>> +
>>> +static inline struct csi2dc_device *
>>> +csi2dc_sd_to_csi2dc_device(struct v4l2_subdev *csi2dc_sd)
>>> +{
>>> +   return container_of(csi2dc_sd, struct csi2dc_device, csi2dc_sd);
>>> +}
>>> +
>>> +static int csi2dc_enum_mbus_code(struct v4l2_subdev *csi2dc_sd,
>>> +                            struct v4l2_subdev_pad_config *cfg,
>>> +                            struct v4l2_subdev_mbus_code_enum *code)
>>> +{
>>> +   struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
>>> +
>>> +   if (code->index >= csi2dc->num_fmts)
>>> +           return -EINVAL;
>>> +
>>> +   code->code = csi2dc->formats[code->index]->mbus_code;
>>> +   return 0;
>>> +}
>>> +
>>> +static int csi2dc_set_fmt(struct v4l2_subdev *csi2dc_sd,
>>> +                     struct v4l2_subdev_pad_config *cfg,
>>> +                     struct v4l2_subdev_format *req_fmt)
>>> +{
>>> +   struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
>>> +   struct csi2dc_format *fmt;
>>> +   int ret, i;
>>> +
>>> +   if (!csi2dc->completed) {
>>> +           dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
>>> +           return 0;
>>> +   }
>>> +
>>> +   for (fmt = csi2dc->formats[0], i = 0; i < csi2dc->num_fmts; fmt++, i++)
>>> +           if (req_fmt->format.code == fmt->mbus_code)
>>> +                   csi2dc->try_fmt = fmt;
>>> +
>>> +   /* in case we could not find the desired format, default to something */
>>> +   if (!csi2dc->try_fmt  ||
>>> +       req_fmt->format.code != csi2dc->try_fmt->mbus_code) {
>>> +           csi2dc->try_fmt = csi2dc->formats[0];
>>> +
>>> +           dev_dbg(csi2dc->dev,
>>> +                   "CSI2DC unsupported format 0x%x, defaulting to 0x%x\n",
>>> +                   req_fmt->format.code, csi2dc->formats[0]->mbus_code);
>>> +
>>> +           req_fmt->format.code = csi2dc->formats[0]->mbus_code;
>>> +   }
>>> +
>>> +   /* if we are just trying, we are done */
>>> +   if (req_fmt->which == V4L2_SUBDEV_FORMAT_TRY)
>>> +           return 0;
>>> +
>>> +   ret = v4l2_subdev_call(csi2dc->input_sd, pad, set_fmt, cfg, req_fmt);
>>> +   if (ret) {
>>> +           dev_err(csi2dc->dev, "input subdev failed %d\n", ret);
>>> +           return ret;
>>> +   }
>>> +
>>> +   csi2dc->cur_fmt = csi2dc->try_fmt;
>>> +   /* update video pipe */
>>> +   csi2dc_vp_update(csi2dc);
>>> +
>>> +   dev_dbg(csi2dc->dev, "CSI2DC new format: 0x%x\n", req_fmt->format.code);
>>> +   return 0;
>>> +}
>>> +
>>> +static int csi2dc_formats_init(struct csi2dc_device *csi2dc)
>>> +{
>>> +   struct csi2dc_format *fmt;
>>> +   struct v4l2_subdev *subdev = csi2dc->input_sd;
>>> +   unsigned int num_fmts, i;
>>> +
>>> +   struct v4l2_subdev_mbus_code_enum mbus_code = {
>>> +           .which = V4L2_SUBDEV_FORMAT_ACTIVE,
>>> +           .index = 0,
>>> +   };
>>> +
>>> +   num_fmts = 0;
>>> +
>>> +   csi2dc->formats = devm_kcalloc(csi2dc->dev,
>>> +                                  ARRAY_SIZE(csi2dc_formats_list),
>>> +                                  sizeof(*csi2dc->formats), GFP_KERNEL);
>>> +   if (!csi2dc->formats)
>>> +           return -ENOMEM;
>>> +
>>> +   while (!v4l2_subdev_call(subdev, pad, enum_mbus_code, NULL,
>>> +          &mbus_code)) {
>>> +           mbus_code.index++;
>>> +           for (fmt = &csi2dc_formats_list[0], i = 0;
>>> +                i < ARRAY_SIZE(csi2dc_formats_list); i++, fmt++)
>>> +                   if (fmt->mbus_code == mbus_code.code) {
>>> +                           csi2dc->formats[num_fmts] = fmt;
>>> +                           num_fmts++;
>>> +                   }
>>> +   }
>>
>> For the reasons explained above and by Sakari, I think this should be dropped
>>
>>> +
>>> +   if (!num_fmts)
>>> +           return -ENXIO;
>>> +
>>> +   csi2dc->num_fmts = num_fmts;
>>> +
>>> +   return 0;
>>> +}
>>> +
>>> +static int csi2dc_power(struct csi2dc_device *csi2dc, int on)
>>> +{
>>> +   int ret = 0;
>>> +
>>> +   if (!csi2dc->completed) {
>>> +           dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
>>> +           return 0;
>>> +   }
>>
>> Can this happen ?
>>
>>> +
>>> +   if (csi2dc->powered_on == on)
>>> +           return 0;
>>
>> Same question
>>
>>> +
>>> +   if (on)
>>> +           ret = clk_prepare_enable(csi2dc->scck);
>>> +   else
>>> +           clk_disable_unprepare(csi2dc->scck);
>>> +   if (ret)
>>> +           dev_err(csi2dc->dev, "failed to enable scck: %d\n", ret);
>>> +
>>> +   /* if powering up, deassert reset line */
>>> +   if (on)
>>> +           csi2dc_writel(csi2dc, CSI2DC_GCTLR, CSI2DC_GCTLR_SWRST);
>>> +
>>> +   /* if powering down, assert reset line */
>>> +   if (!on)
>>> +           csi2dc_writel(csi2dc, CSI2DC_GCTLR, !CSI2DC_GCTLR_SWRST);
>>> +   if (!ret)
>>> +           csi2dc->powered_on = on;
>>
>> Wouldn't this be better coded as
>>
>>          if (on) {
>>                  clk_prepare_enable
>>                  csi2dc_writel(SWRST)
>>                  powered_on = true
>>          } else {
>>                  clk_disable_unrepare
>>                  csi2dc_writel(!SWRST)
>>                  powered_on = false
>>          }
>>> +
>>> +   return ret;
>>> +}
>>> +
>>> +static int csi2dc_s_stream(struct v4l2_subdev *csi2dc_sd, int enable)
>>> +{
>>> +   struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
>>> +
>>> +   if (!csi2dc->completed) {
>>> +           dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
>>> +           return 0;
>>> +   }
>>> +
>>> +   return v4l2_subdev_call(csi2dc->input_sd, video, s_stream, enable);
>>> +}
>>> +
>>> +static int csi2dc_g_frame_interval(struct v4l2_subdev *csi2dc_sd,
>>> +                              struct v4l2_subdev_frame_interval *interval)
>>> +{
>>> +   struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
>>> +
>>> +   if (!csi2dc->completed) {
>>> +           dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
>>> +           return 0;
>>> +   }
>>> +
>>> +   return v4l2_subdev_call(csi2dc->input_sd, video, g_frame_interval,
>>> +                           interval);
>>> +}
>>> +
>>> +static int csi2dc_s_frame_interval(struct v4l2_subdev *csi2dc_sd,
>>> +                              struct v4l2_subdev_frame_interval *interval)
>>> +{
>>> +   struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
>>> +
>>> +   if (!csi2dc->completed) {
>>> +           dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
>>> +           return 0;
>>> +   }
>>> +
>>> +   return v4l2_subdev_call(csi2dc->input_sd, video, s_frame_interval,
>>> +                           interval);
>>> +}
>>> +
>>> +static int csi2dc_enum_frame_size(struct v4l2_subdev *csi2dc_sd,
>>> +                             struct v4l2_subdev_pad_config *cfg,
>>> +                             struct v4l2_subdev_frame_size_enum *fse)
>>> +{
>>> +   struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
>>> +
>>> +   if (!csi2dc->completed) {
>>> +           dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
>>> +           return 0;
>>> +   }
>>> +
>>> +   return v4l2_subdev_call(csi2dc->input_sd, pad, enum_frame_size, cfg,
>>> +                           fse);
>>> +}
>>> +
>>> +static int csi2dc_enum_frame_interval(struct v4l2_subdev *csi2dc_sd,
>>> +                         struct v4l2_subdev_pad_config *cfg,
>>> +                         struct v4l2_subdev_frame_interval_enum *fie)
>>> +{
>>> +   struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
>>> +
>>> +   if (!csi2dc->completed) {
>>> +           dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
>>> +           return 0;
>>> +   }
>>> +
>>> +   return v4l2_subdev_call(csi2dc->input_sd, pad, enum_frame_interval, cfg,
>>> +                           fie);
>>> +}
>>> +
>>> +static const struct v4l2_subdev_pad_ops csi2dc_pad_ops = {
>>> +   .enum_mbus_code = csi2dc_enum_mbus_code,
>>> +   .set_fmt = csi2dc_set_fmt,
>>> +   .enum_frame_size = csi2dc_enum_frame_size,
>>> +   .enum_frame_interval = csi2dc_enum_frame_interval,
>>> +};
>>> +
>>> +static const struct v4l2_subdev_video_ops csi2dc_video_ops = {
>>> +   .s_stream = csi2dc_s_stream,
>>> +   .g_frame_interval = csi2dc_g_frame_interval,
>>> +   .s_frame_interval = csi2dc_s_frame_interval,
>>> +};
>>> +
>>> +static const struct v4l2_subdev_ops csi2dc_subdev_ops = {
>>> +   .pad = &csi2dc_pad_ops,
>>> +   .video = &csi2dc_video_ops,
>>> +};
>>> +
>>> +static int csi2dc_get_mbus_config(struct csi2dc_device *csi2dc)
>>> +{
>>> +   struct v4l2_mbus_config mbus_config = { 0 };
>>> +   int ret;
>>> +
>>> +   ret = v4l2_subdev_call(csi2dc->input_sd, pad, get_mbus_config,
>>> +                          csi2dc->remote_pad, &mbus_config);
>>> +   if (ret == -ENOIOCTLCMD) {
>>> +           dev_dbg(csi2dc->dev,
>>> +                   "no remote mbus configuration available\n");
>>> +           goto csi2dc_get_mbus_config_defaults;
>>> +   }
>>> +
>>> +   if (ret) {
>>> +           dev_err(csi2dc->dev,
>>> +                   "failed to get remote mbus configuration\n");
>>> +           goto csi2dc_get_mbus_config_defaults;
>>
>> This should probably be an error reported to the caller. But this
>> function return value is not checked, so it's probably fine.
>>
>>> +   }
>>> +
>>> +   if (mbus_config.flags & V4L2_MBUS_CSI2_CHANNEL_0)
>>> +           csi2dc->vc = 0;
>>> +   else if (mbus_config.flags & V4L2_MBUS_CSI2_CHANNEL_1)
>>> +           csi2dc->vc = 1;
>>> +   else if (mbus_config.flags & V4L2_MBUS_CSI2_CHANNEL_2)
>>> +           csi2dc->vc = 2;
>>> +   else if (mbus_config.flags & V4L2_MBUS_CSI2_CHANNEL_3)
>>> +           csi2dc->vc = 3;
>>> +
>>> +   dev_dbg(csi2dc->dev, "subdev sending on channel %d\n", csi2dc->vc);
>>> +
>>> +   csi2dc->clk_gated = mbus_config.flags &
>>> +                       V4L2_MBUS_CSI2_NONCONTINUOUS_CLOCK;
>>> +
>>> +   dev_dbg(csi2dc->dev, "%s clock\n",
>>> +           csi2dc->clk_gated ? "gated" : "free running");
>>> +
>>> +   return 0;
>>> +
>>> +csi2dc_get_mbus_config_defaults:
>>> +   csi2dc->vc = 0; /* Virtual ID 0 by default */
>>> +   csi2dc->clk_gated = false; /* Free running clock by default */
>>> +
>>> +   return 0;
>>> +}
>>> +
>>> +static int csi2dc_async_bound(struct v4l2_async_notifier *notifier,
>>> +                         struct v4l2_subdev *subdev,
>>> +                         struct v4l2_async_subdev *asd)
>>> +{
>>> +   struct csi2dc_device *csi2dc = container_of(notifier->v4l2_dev,
>>> +                                   struct csi2dc_device, v4l2_dev);
>>> +   int pad;
>>> +
>>> +   csi2dc->input_sd = subdev;
>>> +
>>> +   pad = media_entity_get_fwnode_pad(&subdev->entity,
>>> +                                     asd->match.fwnode,
>>> +                                     MEDIA_PAD_FL_SOURCE);
>>> +   if (pad < 0) {
>>> +           dev_err(csi2dc->dev, "Failed to find pad for %s\n",
>>> +                   subdev->name);
>>> +           return pad;
>>> +   }
>>> +
>>> +   csi2dc->remote_pad = pad;
>>> +
>>> +   csi2dc_get_mbus_config(csi2dc);
>>
>> The closer to s_stream you call get_mbus_config, the less the chances
>> of receiving a stale configuration, if this can happen.
>>
>>> +
>>> +   return 0;
>>> +}
>>> +
>>> +static int csi2dc_async_complete(struct v4l2_async_notifier *notifier)
>>> +{
>>> +   struct csi2dc_device *csi2dc =
>>> +           container_of(notifier->v4l2_dev, struct csi2dc_device,
>>> +                        v4l2_dev);
>>> +   int ret;
>>> +
>>> +   ret = csi2dc_formats_init(csi2dc);
>>> +   if (ret)
>>> +           return ret;
>>> +
>>> +   ret = v4l2_device_register_subdev_nodes(&csi2dc->v4l2_dev);
>>> +   if (ret < 0) {
>>> +           v4l2_err(&csi2dc->v4l2_dev,
>>> +                    "failed to register subdev nodes\n");
>>> +           return ret;
>>> +   }
>>> +
>>> +   csi2dc->completed = true;
>>> +
>>> +   csi2dc_writel(csi2dc, CSI2DC_GCFG,
>>> +                 (SAMA7G5_HLC & CSI2DC_GCFG_HLC_MASK) |
>>> +                 (csi2dc->clk_gated ? 0 : CSI2DC_GCFG_MIPIFRN));
>>> +
>>> +   csi2dc_writel(csi2dc, CSI2DC_VPCOL,
>>> +                 CSI2DC_VPCOL_COL(0xFFF) & CSI2DC_VPCOL_COL_MASK);
>>> +   csi2dc_writel(csi2dc, CSI2DC_VPROW,
>>> +                 CSI2DC_VPROW_ROW(0xFFF) & CSI2DC_VPROW_ROW_MASK);
>>> +
>>> +   /* once we are completed, we can register ourselves in the pipeline */
>>> +   schedule_work(&csi2dc->workq);
>>> +
>>> +   return ret;
>>> +}
>>> +
>>> +static const struct v4l2_async_notifier_operations csi2dc_async_ops = {
>>> +   .bound = csi2dc_async_bound,
>>> +   .complete = csi2dc_async_complete,
>>> +};
>>> +
>>> +static void csi2dc_cleanup_notifier(struct csi2dc_device *csi2dc)
>>> +{
>>> +   v4l2_async_notifier_unregister(&csi2dc->notifier);
>>> +   v4l2_async_notifier_cleanup(&csi2dc->notifier);
>>> +}
>>> +
>>> +static int csi2dc_prepare_notifier(struct csi2dc_device *csi2dc,
>>> +                              struct device_node *input_parent)
>>> +{
>>> +   int ret;
>>> +
>>> +   v4l2_async_notifier_init(&csi2dc->notifier);
>>> +
>>> +   csi2dc->asd = kzalloc(sizeof(*csi2dc->asd), GFP_KERNEL);
>>> +   if (!csi2dc->asd)
>>> +           return -ENOMEM;
>>> +
>>> +   csi2dc->asd->match_type = V4L2_ASYNC_MATCH_FWNODE;
>>> +   csi2dc->asd->match.fwnode = of_fwnode_handle(input_parent);
>>
>> If you use v4l2_async_notifier_add_fwnode_subdev() the framework does
>> this for you.
>>
>>> +
>>> +   ret = v4l2_async_notifier_add_subdev(&csi2dc->notifier, csi2dc->asd);
>>> +   if (ret) {
>>> +           dev_err(csi2dc->dev, "failed to add async notifier.\n");
>>> +           v4l2_async_notifier_cleanup(&csi2dc->notifier);
>>> +           goto csi2dc_prepare_notifier_err;
>>> +   }
>>> +
>>> +   csi2dc->notifier.ops = &csi2dc_async_ops;
>>> +
>>> +   ret = v4l2_async_notifier_register(&csi2dc->v4l2_dev,
>>> +                                      &csi2dc->notifier);
>>> +
>>> +   if (ret) {
>>> +           dev_err(csi2dc->dev, "fail to register async notifier.\n");
>>
>> Shouldn't you cleanup the notifier if registration fails ?
>>
>>> +           goto csi2dc_prepare_notifier_err;
>>> +   }
>>> +
>>> +csi2dc_prepare_notifier_err:
>>> +   of_node_put(input_parent);
>>> +
>>> +   return ret;
>>> +}
>>> +
>>> +static int csi2dc_of_parse(struct csi2dc_device *csi2dc,
>>> +                      struct device_node *of_node)
>>> +{
>>> +   struct device_node *input_node, *sink_node, *input_parent;
>>> +   struct v4l2_fwnode_endpoint input_endpoint = { 0 },
>>> +                               sink_endpoint = { 0 };
>>> +   int ret;
>>> +
>>> +   input_node = of_graph_get_next_endpoint(of_node, NULL);
>>> +
>>> +   if (!input_node) {
>>> +           dev_err(csi2dc->dev,
>>> +                   "missing port node at %s, input node is mandatory.\n",
>>
>> Please use %pOF to print the node name
>> Also, input_node should be put in the error path
>>
>>> +                   of_node->full_name);
>>> +           return -EINVAL;
>>> +   }
>>> +
>>> +   ret = v4l2_fwnode_endpoint_parse(of_fwnode_handle(input_node),
>>> +                                    &input_endpoint);
>>
>> Please set input_endpoint.bus_type if you know what kind of bus you're
>> dealing with (not having the bindings of the IDI transmitter I'm not
>> sure. Is this V4L2_MBUS_CSI2_DPHY ?)
>>
>>> +
>>> +   if (ret) {
>>> +           dev_err(csi2dc->dev, "endpoint not defined at %s\n",
>>> +                   of_node->full_name);
>>> +           return ret;
>>> +   }
>>> +
>>> +   input_parent = of_graph_get_remote_port_parent(input_node);
>>> +   if (!input_parent) {
>>
>> Missing of_node_put(input_node)
>>
>>> +           dev_err(csi2dc->dev,
>>> +                   "could not get input node's parent node.\n");
>>> +           return -EINVAL;
>>> +   }
>>> +
>>> +   sink_node = of_graph_get_next_endpoint(of_node, input_node);
>>> +
>>> +   if (sink_node)
>>> +           ret = v4l2_fwnode_endpoint_parse(of_fwnode_handle(sink_node),
>>> +                                            &sink_endpoint);
>>
>> Same, set sink_endpoint.bus_type if you know it's MBUS_PARALLEL
>>
>>> +
>>> +   if (!sink_node || ret) {
>>
>> If parsing fail you don't return an error but continue registering the
>> notifier and potentially end up registering the async subdev for this
>> entity even if the endpoint parsing failed.
>>
>>> +           dev_info(csi2dc->dev,
>>> +                    "missing sink node at %s, data pipe available only.\n",
>>> +                    of_node->full_name);
>>> +   } else {
>>> +           csi2dc->video_pipe = true;
>>
>> video_pipe is unused it seems
>>
>>> +
>>> +           dev_dbg(csi2dc->dev, "block %s %d.%d->%d.%d video pipeline\n",
>>> +                   of_node->full_name, input_endpoint.base.port,
>>> +                   input_endpoint.base.id, sink_endpoint.base.port,
>>> +                   sink_endpoint.base.id);
>>> +   }
>>> +
>>> +   of_node_put(sink_node);
>>> +   of_node_put(input_node);
>>> +
>>> +   /* prepare async notifier for subdevice completion */
>>> +   return csi2dc_prepare_notifier(csi2dc, input_parent);
>>> +}
>>> +
>>> +static void csi2dc_workq_handler(struct work_struct *workq)
>>> +{
>>> +   struct csi2dc_device *csi2dc = container_of(workq,
>>> +                                   struct csi2dc_device, workq);
>>> +   int ret;
>>> +
>>> +   if (v4l2_async_register_subdev(&csi2dc->csi2dc_sd))
>>> +           dev_dbg(csi2dc->dev, "failed to register the subdevice\n");
>>
>> That's peculiar, why do you have to schedule this to a workqueue
>> instead of doing this in the complete() callback ?
>>
>>> +
>>> +   ret = csi2dc_power(csi2dc, true);
>>> +   if (ret < 0)
>>> +           v4l2_err(&csi2dc->v4l2_dev, "failed to power on\n");
>>
>> Should the device be powered on at s_stream time ? Possibly with a
>> pm_runtime_get_sync() call ? I see you register pm_runtime operations,
>> but never call get_sync() or _put().
>>
>> What if CONFIG_PM not selected ? Should this driver select it ? Do you
>> have use cases where that's not possible ?
>>
>>> +}
>>> +
>>> +static int csi2dc_probe(struct platform_device *pdev)
>>> +{
>>> +   struct device *dev = &pdev->dev;
>>> +   struct csi2dc_device *csi2dc;
>>> +   struct resource *res = NULL;
>>> +   int ret = 0;
>>> +
>>> +   csi2dc = devm_kzalloc(dev, sizeof(*csi2dc), GFP_KERNEL);
>>> +   if (!csi2dc)
>>> +           return -ENOMEM;
>>> +
>>> +   csi2dc->dev = dev;
>>> +
>>> +   res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>>> +   if (!res)
>>> +           return -EINVAL;
>>
>> devm_ioremap_resource() checks for the validity of 'res' so you can
>> drop the previous two lines
>>
>>> +
>>> +   csi2dc->base = devm_ioremap_resource(dev, res);
>>> +
>>
>> Is the empy line intentional, sometimes you have one, sometimes you
>> don't ?
>>
>>> +   if (IS_ERR(csi2dc->base)) {
>>> +           dev_err(dev, "base address not set\n");
>>
>>
>>> +           return PTR_ERR(csi2dc->base);
>>> +   }
>>> +
>>> +   csi2dc->pclk = devm_clk_get(dev, "pclk");
>>> +   if (IS_ERR(csi2dc->pclk)) {
>>> +           ret = PTR_ERR(csi2dc->pclk);
>>> +           dev_err(dev, "failed to get pclk: %d\n", ret);
>>> +           return ret;
>>
>> Just return PTR_ERR instead of assigning to ret
>>
>>> +   }
>>> +
>>> +   ret = clk_prepare_enable(csi2dc->pclk);
>>> +   if (ret) {
>>> +           dev_err(dev, "failed to enable pclk: %d\n", ret);
>>> +           return ret;
>>> +   }
>>
>> Has this clock to be enabled here or can it be done in the
>> pm_runtime callback ?
>>
>>> +
>>> +   csi2dc->scck = devm_clk_get(dev, "scck");
>>> +   if (IS_ERR(csi2dc->scck)) {
>>> +           ret = PTR_ERR(csi2dc->scck);
>>> +           dev_err(dev, "failed to get scck: %d\n", ret);
>>> +           goto csi2dc_clk_fail;
>>> +   }
>>> +
>>> +   ret = v4l2_device_register(dev, &csi2dc->v4l2_dev);
>>> +   if (ret) {
>>> +           dev_err(dev, "unable to register v4l2 device.\n");
>>> +           goto csi2dc_clk_fail;
>>> +   }
>>> +
>>> +   v4l2_subdev_init(&csi2dc->csi2dc_sd, &csi2dc_subdev_ops);
>>> +
>>> +   csi2dc->csi2dc_sd.owner = THIS_MODULE;
>>> +   csi2dc->csi2dc_sd.dev = dev;
>>> +   snprintf(csi2dc->csi2dc_sd.name, sizeof(csi2dc->csi2dc_sd.name),
>>> +            "CSI2DC.0");
>>> +
>>> +   csi2dc->csi2dc_sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
>>> +   csi2dc->csi2dc_sd.entity.function = MEDIA_ENT_F_VID_IF_BRIDGE;
>>> +   csi2dc->pads[CSI2DC_PAD_SINK].flags = MEDIA_PAD_FL_SINK;
>>> +   csi2dc->pads[CSI2DC_PAD_SOURCE].flags = MEDIA_PAD_FL_SOURCE;
>>
>> Isn't the source pad presence conditional to the presence of
>> port@1 ?
>>
>>> +
>>> +   ret = media_entity_pads_init(&csi2dc->csi2dc_sd.entity, CSI2DC_PADS_NUM,
>>> +                                csi2dc->pads);
>>> +   if (ret < 0) {
>>> +           dev_err(dev, "media entity init failed\n");
>>> +           goto csi2dc_probe_entity_err;
>>> +   }
>>> +
>>> +   v4l2_set_subdevdata(&csi2dc->csi2dc_sd, pdev);
>>> +
>>> +   platform_set_drvdata(pdev, &csi2dc->csi2dc_sd);
>>> +
>>> +   INIT_WORK(&csi2dc->workq, csi2dc_workq_handler);
>>> +
>>> +   ret = csi2dc_of_parse(csi2dc, dev->of_node);
>>> +   if (ret)
>>> +           goto csi2dc_probe_entity_err;
>>> +
>>> +   dev_info(dev, "Microchip CSI2DC version %x\n",
>>> +            csi2dc_readl(csi2dc, CSI2DC_VERSION));
>>> +
>>> +   pm_runtime_set_active(dev);
>>> +   pm_runtime_enable(dev);
>>> +   pm_request_idle(dev);
>>> +
>>> +   return 0;
>>> +
>>> +csi2dc_probe_entity_err:
>>> +   media_entity_cleanup(&csi2dc->csi2dc_sd.entity);
>>> +   v4l2_device_unregister(&csi2dc->v4l2_dev);
>>> +csi2dc_clk_fail:
>>> +   clk_disable_unprepare(csi2dc->pclk);
>>> +   return ret;
>>> +}
>>> +
>>> +static int csi2dc_remove(struct platform_device *pdev)
>>> +{
>>> +   struct v4l2_subdev *csi2dc_sd = platform_get_drvdata(pdev);
>>> +   struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
>>> +
>>> +   pm_runtime_disable(&pdev->dev);
>>> +
>>> +   v4l2_async_unregister_subdev(&csi2dc->csi2dc_sd);
>>> +   csi2dc_cleanup_notifier(csi2dc);
>>> +   media_entity_cleanup(&csi2dc->csi2dc_sd.entity);
>>> +   v4l2_device_unregister(&csi2dc->v4l2_dev);
>>> +   clk_disable_unprepare(csi2dc->pclk);
>>> +
>>> +   return 0;
>>> +}
>>> +
>>> +static int __maybe_unused csi2dc_runtime_suspend(struct device *dev)
>>> +{
>>> +   struct csi2dc_device *csi2dc = dev_get_drvdata(dev);
>>> +
>>> +   return csi2dc_power(csi2dc, false);
>>> +}
>>> +
>>> +static int __maybe_unused csi2dc_runtime_resume(struct device *dev)
>>> +{
>>> +   struct csi2dc_device *csi2dc = dev_get_drvdata(dev);
>>> +
>>> +   return csi2dc_power(csi2dc, true);
>>> +}
>>> +
>>> +static const struct dev_pm_ops csi2dc_dev_pm_ops = {
>>> +   SET_RUNTIME_PM_OPS(csi2dc_runtime_suspend, csi2dc_runtime_resume, NULL)
>>> +};
>>> +
>>> +static const struct of_device_id csi2dc_of_match[] = {
>>> +   { .compatible = "microchip,sama7g5-csi2dc" },
>>> +   { }
>>> +};
>>> +
>>> +MODULE_DEVICE_TABLE(of, csi2dc_of_match);
>>> +
>>> +static struct platform_driver csi2dc_driver = {
>>> +   .probe  = csi2dc_probe,
>>> +   .remove = csi2dc_remove,
>>> +   .driver = {
>>> +           .name           = "microchip-csi2dc",
>>> +           .pm             = &csi2dc_dev_pm_ops,
>>> +           .of_match_table = of_match_ptr(csi2dc_of_match),
>>> +   },
>>> +};
>>> +
>>> +module_platform_driver(csi2dc_driver);
>>> +
>>> +MODULE_AUTHOR("Eugen Hristev <eugen.hristev@microchip.com>");
>>> +MODULE_DESCRIPTION("Microchip CSI2 Demux Controller driver");
>>> +MODULE_LICENSE("GPL v2");
>>> +MODULE_SUPPORTED_DEVICE("video");
>>
>> For my education, what's MODULE_SUPPORTED_DEVICE for ?
> 
> It's "not yet implemented" since 2005, I think it can be dropped :-)
> 
> --
> Regards,
> 
> Laurent Pinchart
> 

Re: [PATCH v5 2/3] media: atmel: introduce microchip csi2dc driver

[Jacopo Mondi]

Hello Eugen,

On Tue, Nov 17, 2020 at 05:24:30PM +0000, Eugen.Hristev@microchip.com wrote:
> On 17.11.2020 14:09, Laurent Pinchart wrote:
> > Hello everybody,
> >
> > On Tue, Nov 17, 2020 at 12:59:02PM +0100, Jacopo Mondi wrote:
> >> On Thu, Nov 12, 2020 at 03:34:36PM +0200, Eugen Hristev wrote:
> >>> Microchip CSI2DC (CSI2 Demultiplexer Controller) is a misc bridge device
> >>> that converts a byte stream in IDI Synopsys format (coming from a CSI2HOST)
> >>> to a pixel stream that can be captured by a sensor controller.
> >>>
> >>> Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
> >>> ---
> >>> Hello,
> >>>
> >>> There still are some open questions regarding the last reviews on the ML.
> >>>
> >>> Regarding the format list which is not const, I cannot have it const because
> >>> I reference elements from this list into a dynamic list which is non-const.
> >>>
> >>> Regarding the presence of the v4l2_dev, without this I cannot add a notifier
> >>> for this device to have it async completed , when the underlying subdevice
> >>> finishes probing.
> >>
> >> I see you have a discussion with Sakari on-going on this, and I have
> >> the very same comment he had.
> >>
> >> Should a sub-notifier be used and this driver should not register any
> >> v4l2_dev but integrate in the media graph of the receiver ?
> >>
> >> For reference, rcar-csi2 uses sub-notifiers and register in the
> >> rcar-vin media graph, it doesn't need to set up a v4l2_dev.
> >>
> >> rcar-vin (the DMA engine driver) that register video nodes and the v4l2-dev
> >> also registers the device nodes for all the connected subdevices.
> >
> > Sub-notifiers were invited for this purpose, so I think they're the
> > right tool.
> >
> >>> Regarding the callbacks for set frame interval, set frame size, etc, I cannot
> >>> remove them because losing functionality to the underlying subdevice, as
> >>> explained in :
> >>> https://lkml.org/lkml/2020/10/12/427
> >>
> >> Using the frame sizes as in the example you reported, if this device has
> >> limitations on the supported sizes, (a min and a max most
> >> probably) that's the only thing that should be exposed from this
> >> driver subdevice. The sensor subdevice instead will report the
> >> available discrete sizes and userspace configures the sensor's source
> >> pad and the bridge's sink pad with the same sizes to properly set up the
> >> capture pipeline. video0 should not report the sizes exposed by the sensor
> >> nor any information that depends on what's connected to it.
> >
> > Agreed. Subdev drivers should remain simple and cover only the subdev
> > they manage. Bundling it together is the job of userspace. In the legacy
> > model it uses to be the job of the top-level V4L2 driver (the one
> > implementing v4l2_device), but that's legacy, especially for embedded
> > camera use cases. In any case, the top-level logic must not be spread
> > across subdevices.
> >
> >> I know what your next question is: what about existing application
> >> that only know about video0 and want to setup everything from there. I
> >> understand vendors not wanting to wrap gstreamer or what is used in
> >> the wild in custom scripts that sets up the pipeline opportunely
> >> before streaming, and I'm pretty sure you know what is the solution I
> >> would propose for this :)
> >>
> >> I've just gone through the same path with RPi's Unicam, that does the
> >> same thing as your one does: it's an MC driver, but wants to control
> >> the sensor through the v4l2-subdev kAPI to support legacy use cases
> >> not covered by libcamera. The fact is that we're stuck in this limbo
> >> where MC pipeline tries to decouple components one from each other and
> >> delegate their configuration to userspace, but at the same time
> >> vendors want to be able to use the simple plain video node centric
> >> interface because of their existing user base, so I understand your
> >> discomfort, but the 'simple plain' approach is what's preventing Linux
> >> platforms to be in-par with proprietary and custom solutions for any
> >> use case that is not a simple frame capture, so I think it's fair for
> >> mainline to push for this evolution to happen. Just my2c of course.
> >
> > Compatibility with the userspace of downstream kernels is important, but
> > that's a downstream kernel issue. In mainline we want to go the MC way,
> > and downstream can then, if desired, implement the configuration of the
> > pipeline in the top-level V4L2 driver in the kernel to support the
> > existing userbase. For new drivers I wouldn't recommend that, for
> > existing downstream drivers it may be required.
>
> Hello,
>
> First of all thank you for the review and explanations.
>
> I am still confused about how does the userspace know which elements are
> in the pipeline and how to connect them ?

Using the media-controller uAPI to inspect, explore and configure the
media graph (it's mostly about enabling and disabling media links),
and using the v4l2 subdev uAPI to configure formats, sizes and such on
each subdevice device node associated with a media entity. Finally,
using the v4l2 uAPI to stream from the top-level driver that expose a
video device node.

It's really (conceptually) not different than doing the same using
media-ctl and v4l2-ctl.

> And if this is the case, what is the purpose of the endpoints in the DT ?
>

DTS describe the hardware. Usually a driver parses the firmware graph
to create and model the media graph and the available connections
between media entities but there's no requirement to have a 1-to-1
match (as far I'm aware).

Media links on a media graph then need to be enabled opportunely
depending on the desired use case, the platform topology etc

> At this moment, I just use the /dev/video0, because the top v4l2 driver
> configures the subdevice, and this subdevice configures it's own
> subdevice and so on, until the sensor itself.
>
> My top v4l2 driver will not 'complete' unless a subdevice registers
> itself , and if this subdevice does not provide any information
> regarding its formats, the probe of the top v4l2 driver will fail,
> because it will not find compatibility between it's supported input
> formats and what the subdevice provides.

ouch, I see.. Which driver is that ?

If that's an MC driver, and that seems the case, it should not bother
validating the subdevice formats, but only care about listing what its
capabilities are.

>
> So what to do in this case ? Libcamera will configure this whole
> pipeline for me , if the drivers just probe ( and start/stop streaming
> by selecting the respective registers) ? or how to do this whole
> pipeline configuration ?
>

Well, libcamera offers a framework to enable specialized code (called
"pipeline handler") to operate under an high-level API towards application
and implement image tuning algorithms on top of that common API.

The code to configure the pipeline is device specific (unless your
pipeline is very simple). So it's not that libcamera just magically
knows how to operate on every platforms it runs on, it needs platform
specific code to do so. What you get in exchange is an high level API
to offer to application developers, a framework to implement 3A and
tuning algorithms, integration with a growing set of other userspace
frameworks (android, gstreamer, pipewire and a legacy v4l2-compat
layer)

We have a lengthy pipeline handler writers guide that might help
better explain this:

https://git.linuxtv.org/libcamera.git/tree/Documentation/guides/pipeline-handler.rst
(you might want to compile libcamera to be able to render it in a browser)

Hope this helps to clarify things a bit

>
> >
> >> Some more comments on the implementation below
> >>
> >>> Changes in v5:
> >>> - only in bindings
> >>>
> >>> Changes in v4:
> >>> - now using get_mbus_config ops to get data from the subdevice, like the
> >>> virtual channel id, and the clock type.
> >>> - now having possibility to select any of the RAW10 data modes
> >>> - at completion time, select which formats are also available in the subdevice,
> >>> and move to the dynamic list accordingly
> >>> - changed the pipeline integration, do not advertise subdev ready at probe time.
> >>> wait until completion is done, and then start a workqueue that will register
> >>> this device as a subdevice for the next element in pipeline.
> >>> - moved the s_power code into a different function called now csi2dc_power
> >>> that is called with CONFIG_PM functions. This is also called at completion,
> >>> to have the device ready in case CONFIG_PM is not selected on the platform.
> >>> - merged try_fmt into set_fmt
> >>> - driver cleanup, wrapped lines over 80 characters
> >>>
> >>> Changes in v2:
> >>> - moved driver to platform/atmel
> >>> - fixed minor things as per Sakari's review
> >>> - still some things from v2 review are not yet addressed, to be followed up
> >>>
> >>>   drivers/media/platform/atmel/Kconfig          |  13 +
> >>>   drivers/media/platform/atmel/Makefile         |   1 +
> >>>   .../media/platform/atmel/microchip-csi2dc.c   | 785 ++++++++++++++++++
> >>>   3 files changed, 799 insertions(+)
> >>>   create mode 100644 drivers/media/platform/atmel/microchip-csi2dc.c
> >>>
> >>> diff --git a/drivers/media/platform/atmel/Kconfig b/drivers/media/platform/atmel/Kconfig
> >>> index 99b51213f871..147e1c14129b 100644
> >>> --- a/drivers/media/platform/atmel/Kconfig
> >>> +++ b/drivers/media/platform/atmel/Kconfig
> >>> @@ -32,3 +32,16 @@ config VIDEO_ATMEL_ISI
> >>>      help
> >>>        This module makes the ATMEL Image Sensor Interface available
> >>>        as a v4l2 device.
> >>> +
> >>> +config VIDEO_MICROCHIP_CSI2DC
> >>> +   tristate "Microchip CSI2 Demux Controller"
> >>> +   depends on VIDEO_V4L2 && COMMON_CLK && OF
> >>> +   depends on ARCH_AT91 || COMPILE_TEST
> >>> +   select MEDIA_CONTROLLER
> >>> +   select VIDEO_V4L2_SUBDEV_API
> >>> +   select V4L2_FWNODE
> >>> +   help
> >>> +     CSI2 Demux Controller driver. CSI2DC is a helper chip
> >>> +     that converts IDI interface byte stream to a parallel pixel stream.
> >>> +     It supports various RAW formats as input.
> >>> +     Performs clock domain crossing between hardware blocks.
> >>
> >> Is the last phrase necessary ? Also missing the usual
> >>
> >>          To compile this driver as a module, choose M here: the
> >>          module will be called ...
> >>
> >>> diff --git a/drivers/media/platform/atmel/Makefile b/drivers/media/platform/atmel/Makefile
> >>> index c5c01556c653..8e80af500bf5 100644
> >>> --- a/drivers/media/platform/atmel/Makefile
> >>> +++ b/drivers/media/platform/atmel/Makefile
> >>> @@ -5,3 +5,4 @@ atmel-xisc-objs = atmel-sama7g5-isc.o atmel-isc-base.o
> >>>   obj-$(CONFIG_VIDEO_ATMEL_ISI) += atmel-isi.o
> >>>   obj-$(CONFIG_VIDEO_ATMEL_ISC) += atmel-isc.o
> >>>   obj-$(CONFIG_VIDEO_ATMEL_XISC) += atmel-xisc.o
> >>> +obj-$(CONFIG_VIDEO_MICROCHIP_CSI2DC) += microchip-csi2dc.o
> >>> diff --git a/drivers/media/platform/atmel/microchip-csi2dc.c b/drivers/media/platform/atmel/microchip-csi2dc.c
> >>> new file mode 100644
> >>> index 000000000000..fda1d5882dbb
> >>> --- /dev/null
> >>> +++ b/drivers/media/platform/atmel/microchip-csi2dc.c
> >>> @@ -0,0 +1,785 @@
> >>> +// SPDX-License-Identifier: GPL-2.0
> >>
> >> Nit: I see GPL-2.0 listed as deprecated by spdx.org
> >> Should you use one of:
> >>                GPL-2.0-only
> >>                        GPL-2.0-or-later
> >>
> >>> +/*
> >>> + * Microchip CSI2 Demux Controller (CSI2DC) driver
> >>> + *
> >>> + * Copyright (C) 2018-2020 Microchip Technology, Inc.
> >>> + *
> >>> + * Author: Eugen Hristev <eugen.hristev@microchip.com>
> >>> + *
> >>> + */
> >>> +
> >>> +#include <linux/clk.h>
> >>> +#include <linux/module.h>
> >>> +#include <linux/of.h>
> >>> +#include <linux/of_graph.h>
> >>> +#include <linux/platform_device.h>
> >>> +#include <linux/pm_runtime.h>
> >>> +#include <linux/videodev2.h>
> >>> +
> >>> +#include <media/v4l2-device.h>
> >>> +#include <media/v4l2-fwnode.h>
> >>> +#include <media/v4l2-subdev.h>
> >>> +#include <media/videobuf2-dma-contig.h>
> >>> +
> >>> +/* Global configuration register */
> >>> +#define CSI2DC_GCFG                        0x0
> >>> +
> >>> +/* MIPI sensor pixel clock is free running */
> >>> +#define CSI2DC_GCFG_MIPIFRN                BIT(0)
> >>> +/* Output waveform inter-line minimum delay */
> >>> +#define CSI2DC_GCFG_HLC(v)         ((v) << 4)
> >>> +#define CSI2DC_GCFG_HLC_MASK               GENMASK(7, 4)
> >>> +/* SAMA7G5 requires a HLC delay of 15 */
> >>> +#define SAMA7G5_HLC                        (15)
> >>> +
> >>> +/* Global control register */
> >>> +#define CSI2DC_GCTLR                       0x04
> >>> +#define CSI2DC_GCTLR_SWRST         BIT(0)
> >>> +
> >>> +/* Global status register */
> >>> +#define CSI2DC_GS                  0x08
> >>> +
> >>> +/* SSP interrupt status register */
> >>> +#define CSI2DC_SSPIS                       0x28
> >>> +/* Pipe update register */
> >>> +#define CSI2DC_PU                  0xC0
> >>> +/* Video pipe attributes update */
> >>> +#define CSI2DC_PU_VP                       BIT(0)
> >>> +
> >>> +/* Pipe update status register */
> >>> +#define CSI2DC_PUS                 0xC4
> >>> +
> >>> +/* Video pipeline enable register */
> >>> +#define CSI2DC_VPE                 0xF8
> >>> +#define CSI2DC_VPE_ENABLE          BIT(0)
> >>> +
> >>> +/* Video pipeline configuration register */
> >>> +#define CSI2DC_VPCFG                       0xFC
> >>> +/* Data type */
> >>> +#define CSI2DC_VPCFG_DT(v)         ((v) << 0)
> >>> +#define CSI2DC_VPCFG_DT_MASK               GENMASK(5, 0)
> >>> +/* Virtual channel identifier */
> >>> +#define CSI2DC_VPCFG_VC(v)         ((v) << 6)
> >>> +#define CSI2DC_VPCFG_VC_MASK               GENMASK(7, 6)
> >>> +/* Decompression enable */
> >>> +#define CSI2DC_VPCFG_DE                    BIT(8)
> >>> +/* Decoder mode */
> >>> +#define CSI2DC_VPCFG_DM(v)         ((v) << 9)
> >>> +#define CSI2DC_VPCFG_DM_DECODER8TO12       0
> >>> +/* Decoder predictor 2 selection */
> >>> +#define CSI2DC_VPCFG_DP2           BIT(12)
> >>> +/* Recommended memory storage */
> >>> +#define CSI2DC_VPCFG_RMS           BIT(13)
> >>> +/* Post adjustment */
> >>> +#define CSI2DC_VPCFG_PA                    BIT(14)
> >>> +
> >>> +/* Video pipeline column register */
> >>> +#define CSI2DC_VPCOL                       0x100
> >>> +/* Column number */
> >>> +#define CSI2DC_VPCOL_COL(v)                ((v) << 0)
> >>> +#define CSI2DC_VPCOL_COL_MASK              GENMASK(15, 0)
> >>> +
> >>> +/* Video pipeline row register */
> >>> +#define CSI2DC_VPROW                       0x104
> >>> +/* Row number */
> >>> +#define CSI2DC_VPROW_ROW(v)                ((v) << 0)
> >>> +#define CSI2DC_VPROW_ROW_MASK              GENMASK(15, 0)
> >>> +
> >>> +/* Version register */
> >>> +#define CSI2DC_VERSION                     0x1FC
> >>> +
> >>> +/* register read/write helpers */
> >>> +#define csi2dc_readl(st, reg)              readl_relaxed((st)->base + (reg))
> >>> +#define csi2dc_writel(st, reg, val)        writel_relaxed((val), \
> >>> +                                   (st)->base + (reg))
> >>> +
> >>> +/* supported RAW data types */
> >>> +#define CSI2DC_DT_RAW6                     0x28
> >>> +#define CSI2DC_DT_RAW7                     0x29
> >>> +#define CSI2DC_DT_RAW8                     0x2A
> >>> +#define CSI2DC_DT_RAW10                    0x2B
> >>> +#define CSI2DC_DT_RAW12                    0x2C
> >>> +#define CSI2DC_DT_RAW14                    0x2D
> >>> +
> >>> +struct csi2dc_format {
> >>> +   u32                             mbus_code;
> >>> +   u32                             dt;
> >>> +};
> >>> +
> >>> +static struct csi2dc_format csi2dc_formats_list[] = {
> >>> +   {
> >>> +           .mbus_code =            MEDIA_BUS_FMT_SRGGB10_1X10,
> >>> +           .dt =                   CSI2DC_DT_RAW10,
> >>> +   }, {
> >>> +           .mbus_code =            MEDIA_BUS_FMT_SBGGR10_1X10,
> >>> +           .dt =                   CSI2DC_DT_RAW10,
> >>> +   }, {
> >>> +           .mbus_code =            MEDIA_BUS_FMT_SGRBG10_1X10,
> >>> +           .dt =                   CSI2DC_DT_RAW10,
> >>> +   }, {
> >>> +           .mbus_code =            MEDIA_BUS_FMT_SGBRG10_1X10,
> >>> +           .dt =                   CSI2DC_DT_RAW10,
> >>> +   },
> >>> +};
> >>> +
> >>> +enum mipi_csi_pads {
> >>> +   CSI2DC_PAD_SINK                 = 0,
> >>> +   CSI2DC_PAD_SOURCE               = 1,
> >>> +   CSI2DC_PADS_NUM                 = 2,
> >>> +};
> >>> +
> >>> +struct csi2dc_device {
> >>> +   void __iomem                    *base;
> >>> +   struct v4l2_subdev              csi2dc_sd;
> >>> +   struct device                   *dev;
> >>> +   struct v4l2_device              v4l2_dev;
> >>> +   struct clk                      *pclk;
> >>> +   struct clk                      *scck;
> >>> +
> >>> +   bool                            video_pipe;
> >>> +
> >>> +   u32                             num_fmts;
> >>> +   struct csi2dc_format            **formats;
> >>> +
> >>> +   struct csi2dc_format            *cur_fmt;
> >>> +   struct csi2dc_format            *try_fmt;
> >>> +
> >>> +   struct media_pad                pads[CSI2DC_PADS_NUM];
> >>> +
> >>> +   bool                            clk_gated;
> >>> +   u32                             vc;
> >>> +
> >>> +   struct v4l2_async_subdev        *asd;
> >>> +   struct v4l2_async_notifier      notifier;
> >>> +
> >>> +   struct v4l2_subdev              *input_sd;
> >>> +
> >>> +   u32                             remote_pad;
> >>> +
> >>> +   bool                            completed;
> >>> +   bool                            powered_on;
> >>> +
> >>> +   struct work_struct              workq;
> >>> +};
> >>> +
> >>> +static void csi2dc_vp_update(struct csi2dc_device *csi2dc)
> >>> +{
> >>> +   u32 vp;
> >>> +
> >>> +   vp = CSI2DC_VPCFG_DT(csi2dc->cur_fmt->dt) & CSI2DC_VPCFG_DT_MASK;
> >>> +   vp |= CSI2DC_VPCFG_VC(csi2dc->vc) & CSI2DC_VPCFG_VC_MASK;
> >>> +   vp &= ~CSI2DC_VPCFG_DE;
> >>> +   vp |= CSI2DC_VPCFG_DM(CSI2DC_VPCFG_DM_DECODER8TO12);
> >>> +   vp &= ~CSI2DC_VPCFG_DP2;
> >>> +   vp &= ~CSI2DC_VPCFG_RMS;
> >>> +   vp |= CSI2DC_VPCFG_PA;
> >>> +
> >>> +   csi2dc_writel(csi2dc, CSI2DC_VPCFG, vp);
> >>> +   csi2dc_writel(csi2dc, CSI2DC_VPE, CSI2DC_VPE_ENABLE);
> >>> +   csi2dc_writel(csi2dc, CSI2DC_PU, CSI2DC_PU_VP);
> >>> +}
> >>> +
> >>> +static inline struct csi2dc_device *
> >>> +csi2dc_sd_to_csi2dc_device(struct v4l2_subdev *csi2dc_sd)
> >>> +{
> >>> +   return container_of(csi2dc_sd, struct csi2dc_device, csi2dc_sd);
> >>> +}
> >>> +
> >>> +static int csi2dc_enum_mbus_code(struct v4l2_subdev *csi2dc_sd,
> >>> +                            struct v4l2_subdev_pad_config *cfg,
> >>> +                            struct v4l2_subdev_mbus_code_enum *code)
> >>> +{
> >>> +   struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
> >>> +
> >>> +   if (code->index >= csi2dc->num_fmts)
> >>> +           return -EINVAL;
> >>> +
> >>> +   code->code = csi2dc->formats[code->index]->mbus_code;
> >>> +   return 0;
> >>> +}
> >>> +
> >>> +static int csi2dc_set_fmt(struct v4l2_subdev *csi2dc_sd,
> >>> +                     struct v4l2_subdev_pad_config *cfg,
> >>> +                     struct v4l2_subdev_format *req_fmt)
> >>> +{
> >>> +   struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
> >>> +   struct csi2dc_format *fmt;
> >>> +   int ret, i;
> >>> +
> >>> +   if (!csi2dc->completed) {
> >>> +           dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
> >>> +           return 0;
> >>> +   }
> >>> +
> >>> +   for (fmt = csi2dc->formats[0], i = 0; i < csi2dc->num_fmts; fmt++, i++)
> >>> +           if (req_fmt->format.code == fmt->mbus_code)
> >>> +                   csi2dc->try_fmt = fmt;
> >>> +
> >>> +   /* in case we could not find the desired format, default to something */
> >>> +   if (!csi2dc->try_fmt  ||
> >>> +       req_fmt->format.code != csi2dc->try_fmt->mbus_code) {
> >>> +           csi2dc->try_fmt = csi2dc->formats[0];
> >>> +
> >>> +           dev_dbg(csi2dc->dev,
> >>> +                   "CSI2DC unsupported format 0x%x, defaulting to 0x%x\n",
> >>> +                   req_fmt->format.code, csi2dc->formats[0]->mbus_code);
> >>> +
> >>> +           req_fmt->format.code = csi2dc->formats[0]->mbus_code;
> >>> +   }
> >>> +
> >>> +   /* if we are just trying, we are done */
> >>> +   if (req_fmt->which == V4L2_SUBDEV_FORMAT_TRY)
> >>> +           return 0;
> >>> +
> >>> +   ret = v4l2_subdev_call(csi2dc->input_sd, pad, set_fmt, cfg, req_fmt);
> >>> +   if (ret) {
> >>> +           dev_err(csi2dc->dev, "input subdev failed %d\n", ret);
> >>> +           return ret;
> >>> +   }
> >>> +
> >>> +   csi2dc->cur_fmt = csi2dc->try_fmt;
> >>> +   /* update video pipe */
> >>> +   csi2dc_vp_update(csi2dc);
> >>> +
> >>> +   dev_dbg(csi2dc->dev, "CSI2DC new format: 0x%x\n", req_fmt->format.code);
> >>> +   return 0;
> >>> +}
> >>> +
> >>> +static int csi2dc_formats_init(struct csi2dc_device *csi2dc)
> >>> +{
> >>> +   struct csi2dc_format *fmt;
> >>> +   struct v4l2_subdev *subdev = csi2dc->input_sd;
> >>> +   unsigned int num_fmts, i;
> >>> +
> >>> +   struct v4l2_subdev_mbus_code_enum mbus_code = {
> >>> +           .which = V4L2_SUBDEV_FORMAT_ACTIVE,
> >>> +           .index = 0,
> >>> +   };
> >>> +
> >>> +   num_fmts = 0;
> >>> +
> >>> +   csi2dc->formats = devm_kcalloc(csi2dc->dev,
> >>> +                                  ARRAY_SIZE(csi2dc_formats_list),
> >>> +                                  sizeof(*csi2dc->formats), GFP_KERNEL);
> >>> +   if (!csi2dc->formats)
> >>> +           return -ENOMEM;
> >>> +
> >>> +   while (!v4l2_subdev_call(subdev, pad, enum_mbus_code, NULL,
> >>> +          &mbus_code)) {
> >>> +           mbus_code.index++;
> >>> +           for (fmt = &csi2dc_formats_list[0], i = 0;
> >>> +                i < ARRAY_SIZE(csi2dc_formats_list); i++, fmt++)
> >>> +                   if (fmt->mbus_code == mbus_code.code) {
> >>> +                           csi2dc->formats[num_fmts] = fmt;
> >>> +                           num_fmts++;
> >>> +                   }
> >>> +   }
> >>
> >> For the reasons explained above and by Sakari, I think this should be dropped
> >>
> >>> +
> >>> +   if (!num_fmts)
> >>> +           return -ENXIO;
> >>> +
> >>> +   csi2dc->num_fmts = num_fmts;
> >>> +
> >>> +   return 0;
> >>> +}
> >>> +
> >>> +static int csi2dc_power(struct csi2dc_device *csi2dc, int on)
> >>> +{
> >>> +   int ret = 0;
> >>> +
> >>> +   if (!csi2dc->completed) {
> >>> +           dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
> >>> +           return 0;
> >>> +   }
> >>
> >> Can this happen ?
> >>
> >>> +
> >>> +   if (csi2dc->powered_on == on)
> >>> +           return 0;
> >>
> >> Same question
> >>
> >>> +
> >>> +   if (on)
> >>> +           ret = clk_prepare_enable(csi2dc->scck);
> >>> +   else
> >>> +           clk_disable_unprepare(csi2dc->scck);
> >>> +   if (ret)
> >>> +           dev_err(csi2dc->dev, "failed to enable scck: %d\n", ret);
> >>> +
> >>> +   /* if powering up, deassert reset line */
> >>> +   if (on)
> >>> +           csi2dc_writel(csi2dc, CSI2DC_GCTLR, CSI2DC_GCTLR_SWRST);
> >>> +
> >>> +   /* if powering down, assert reset line */
> >>> +   if (!on)
> >>> +           csi2dc_writel(csi2dc, CSI2DC_GCTLR, !CSI2DC_GCTLR_SWRST);
> >>> +   if (!ret)
> >>> +           csi2dc->powered_on = on;
> >>
> >> Wouldn't this be better coded as
> >>
> >>          if (on) {
> >>                  clk_prepare_enable
> >>                  csi2dc_writel(SWRST)
> >>                  powered_on = true
> >>          } else {
> >>                  clk_disable_unrepare
> >>                  csi2dc_writel(!SWRST)
> >>                  powered_on = false
> >>          }
> >>> +
> >>> +   return ret;
> >>> +}
> >>> +
> >>> +static int csi2dc_s_stream(struct v4l2_subdev *csi2dc_sd, int enable)
> >>> +{
> >>> +   struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
> >>> +
> >>> +   if (!csi2dc->completed) {
> >>> +           dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
> >>> +           return 0;
> >>> +   }
> >>> +
> >>> +   return v4l2_subdev_call(csi2dc->input_sd, video, s_stream, enable);
> >>> +}
> >>> +
> >>> +static int csi2dc_g_frame_interval(struct v4l2_subdev *csi2dc_sd,
> >>> +                              struct v4l2_subdev_frame_interval *interval)
> >>> +{
> >>> +   struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
> >>> +
> >>> +   if (!csi2dc->completed) {
> >>> +           dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
> >>> +           return 0;
> >>> +   }
> >>> +
> >>> +   return v4l2_subdev_call(csi2dc->input_sd, video, g_frame_interval,
> >>> +                           interval);
> >>> +}
> >>> +
> >>> +static int csi2dc_s_frame_interval(struct v4l2_subdev *csi2dc_sd,
> >>> +                              struct v4l2_subdev_frame_interval *interval)
> >>> +{
> >>> +   struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
> >>> +
> >>> +   if (!csi2dc->completed) {
> >>> +           dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
> >>> +           return 0;
> >>> +   }
> >>> +
> >>> +   return v4l2_subdev_call(csi2dc->input_sd, video, s_frame_interval,
> >>> +                           interval);
> >>> +}
> >>> +
> >>> +static int csi2dc_enum_frame_size(struct v4l2_subdev *csi2dc_sd,
> >>> +                             struct v4l2_subdev_pad_config *cfg,
> >>> +                             struct v4l2_subdev_frame_size_enum *fse)
> >>> +{
> >>> +   struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
> >>> +
> >>> +   if (!csi2dc->completed) {
> >>> +           dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
> >>> +           return 0;
> >>> +   }
> >>> +
> >>> +   return v4l2_subdev_call(csi2dc->input_sd, pad, enum_frame_size, cfg,
> >>> +                           fse);
> >>> +}
> >>> +
> >>> +static int csi2dc_enum_frame_interval(struct v4l2_subdev *csi2dc_sd,
> >>> +                         struct v4l2_subdev_pad_config *cfg,
> >>> +                         struct v4l2_subdev_frame_interval_enum *fie)
> >>> +{
> >>> +   struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
> >>> +
> >>> +   if (!csi2dc->completed) {
> >>> +           dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
> >>> +           return 0;
> >>> +   }
> >>> +
> >>> +   return v4l2_subdev_call(csi2dc->input_sd, pad, enum_frame_interval, cfg,
> >>> +                           fie);
> >>> +}
> >>> +
> >>> +static const struct v4l2_subdev_pad_ops csi2dc_pad_ops = {
> >>> +   .enum_mbus_code = csi2dc_enum_mbus_code,
> >>> +   .set_fmt = csi2dc_set_fmt,
> >>> +   .enum_frame_size = csi2dc_enum_frame_size,
> >>> +   .enum_frame_interval = csi2dc_enum_frame_interval,
> >>> +};
> >>> +
> >>> +static const struct v4l2_subdev_video_ops csi2dc_video_ops = {
> >>> +   .s_stream = csi2dc_s_stream,
> >>> +   .g_frame_interval = csi2dc_g_frame_interval,
> >>> +   .s_frame_interval = csi2dc_s_frame_interval,
> >>> +};
> >>> +
> >>> +static const struct v4l2_subdev_ops csi2dc_subdev_ops = {
> >>> +   .pad = &csi2dc_pad_ops,
> >>> +   .video = &csi2dc_video_ops,
> >>> +};
> >>> +
> >>> +static int csi2dc_get_mbus_config(struct csi2dc_device *csi2dc)
> >>> +{
> >>> +   struct v4l2_mbus_config mbus_config = { 0 };
> >>> +   int ret;
> >>> +
> >>> +   ret = v4l2_subdev_call(csi2dc->input_sd, pad, get_mbus_config,
> >>> +                          csi2dc->remote_pad, &mbus_config);
> >>> +   if (ret == -ENOIOCTLCMD) {
> >>> +           dev_dbg(csi2dc->dev,
> >>> +                   "no remote mbus configuration available\n");
> >>> +           goto csi2dc_get_mbus_config_defaults;
> >>> +   }
> >>> +
> >>> +   if (ret) {
> >>> +           dev_err(csi2dc->dev,
> >>> +                   "failed to get remote mbus configuration\n");
> >>> +           goto csi2dc_get_mbus_config_defaults;
> >>
> >> This should probably be an error reported to the caller. But this
> >> function return value is not checked, so it's probably fine.
> >>
> >>> +   }
> >>> +
> >>> +   if (mbus_config.flags & V4L2_MBUS_CSI2_CHANNEL_0)
> >>> +           csi2dc->vc = 0;
> >>> +   else if (mbus_config.flags & V4L2_MBUS_CSI2_CHANNEL_1)
> >>> +           csi2dc->vc = 1;
> >>> +   else if (mbus_config.flags & V4L2_MBUS_CSI2_CHANNEL_2)
> >>> +           csi2dc->vc = 2;
> >>> +   else if (mbus_config.flags & V4L2_MBUS_CSI2_CHANNEL_3)
> >>> +           csi2dc->vc = 3;
> >>> +
> >>> +   dev_dbg(csi2dc->dev, "subdev sending on channel %d\n", csi2dc->vc);
> >>> +
> >>> +   csi2dc->clk_gated = mbus_config.flags &
> >>> +                       V4L2_MBUS_CSI2_NONCONTINUOUS_CLOCK;
> >>> +
> >>> +   dev_dbg(csi2dc->dev, "%s clock\n",
> >>> +           csi2dc->clk_gated ? "gated" : "free running");
> >>> +
> >>> +   return 0;
> >>> +
> >>> +csi2dc_get_mbus_config_defaults:
> >>> +   csi2dc->vc = 0; /* Virtual ID 0 by default */
> >>> +   csi2dc->clk_gated = false; /* Free running clock by default */
> >>> +
> >>> +   return 0;
> >>> +}
> >>> +
> >>> +static int csi2dc_async_bound(struct v4l2_async_notifier *notifier,
> >>> +                         struct v4l2_subdev *subdev,
> >>> +                         struct v4l2_async_subdev *asd)
> >>> +{
> >>> +   struct csi2dc_device *csi2dc = container_of(notifier->v4l2_dev,
> >>> +                                   struct csi2dc_device, v4l2_dev);
> >>> +   int pad;
> >>> +
> >>> +   csi2dc->input_sd = subdev;
> >>> +
> >>> +   pad = media_entity_get_fwnode_pad(&subdev->entity,
> >>> +                                     asd->match.fwnode,
> >>> +                                     MEDIA_PAD_FL_SOURCE);
> >>> +   if (pad < 0) {
> >>> +           dev_err(csi2dc->dev, "Failed to find pad for %s\n",
> >>> +                   subdev->name);
> >>> +           return pad;
> >>> +   }
> >>> +
> >>> +   csi2dc->remote_pad = pad;
> >>> +
> >>> +   csi2dc_get_mbus_config(csi2dc);
> >>
> >> The closer to s_stream you call get_mbus_config, the less the chances
> >> of receiving a stale configuration, if this can happen.
> >>
> >>> +
> >>> +   return 0;
> >>> +}
> >>> +
> >>> +static int csi2dc_async_complete(struct v4l2_async_notifier *notifier)
> >>> +{
> >>> +   struct csi2dc_device *csi2dc =
> >>> +           container_of(notifier->v4l2_dev, struct csi2dc_device,
> >>> +                        v4l2_dev);
> >>> +   int ret;
> >>> +
> >>> +   ret = csi2dc_formats_init(csi2dc);
> >>> +   if (ret)
> >>> +           return ret;
> >>> +
> >>> +   ret = v4l2_device_register_subdev_nodes(&csi2dc->v4l2_dev);
> >>> +   if (ret < 0) {
> >>> +           v4l2_err(&csi2dc->v4l2_dev,
> >>> +                    "failed to register subdev nodes\n");
> >>> +           return ret;
> >>> +   }
> >>> +
> >>> +   csi2dc->completed = true;
> >>> +
> >>> +   csi2dc_writel(csi2dc, CSI2DC_GCFG,
> >>> +                 (SAMA7G5_HLC & CSI2DC_GCFG_HLC_MASK) |
> >>> +                 (csi2dc->clk_gated ? 0 : CSI2DC_GCFG_MIPIFRN));
> >>> +
> >>> +   csi2dc_writel(csi2dc, CSI2DC_VPCOL,
> >>> +                 CSI2DC_VPCOL_COL(0xFFF) & CSI2DC_VPCOL_COL_MASK);
> >>> +   csi2dc_writel(csi2dc, CSI2DC_VPROW,
> >>> +                 CSI2DC_VPROW_ROW(0xFFF) & CSI2DC_VPROW_ROW_MASK);
> >>> +
> >>> +   /* once we are completed, we can register ourselves in the pipeline */
> >>> +   schedule_work(&csi2dc->workq);
> >>> +
> >>> +   return ret;
> >>> +}
> >>> +
> >>> +static const struct v4l2_async_notifier_operations csi2dc_async_ops = {
> >>> +   .bound = csi2dc_async_bound,
> >>> +   .complete = csi2dc_async_complete,
> >>> +};
> >>> +
> >>> +static void csi2dc_cleanup_notifier(struct csi2dc_device *csi2dc)
> >>> +{
> >>> +   v4l2_async_notifier_unregister(&csi2dc->notifier);
> >>> +   v4l2_async_notifier_cleanup(&csi2dc->notifier);
> >>> +}
> >>> +
> >>> +static int csi2dc_prepare_notifier(struct csi2dc_device *csi2dc,
> >>> +                              struct device_node *input_parent)
> >>> +{
> >>> +   int ret;
> >>> +
> >>> +   v4l2_async_notifier_init(&csi2dc->notifier);
> >>> +
> >>> +   csi2dc->asd = kzalloc(sizeof(*csi2dc->asd), GFP_KERNEL);
> >>> +   if (!csi2dc->asd)
> >>> +           return -ENOMEM;
> >>> +
> >>> +   csi2dc->asd->match_type = V4L2_ASYNC_MATCH_FWNODE;
> >>> +   csi2dc->asd->match.fwnode = of_fwnode_handle(input_parent);
> >>
> >> If you use v4l2_async_notifier_add_fwnode_subdev() the framework does
> >> this for you.
> >>
> >>> +
> >>> +   ret = v4l2_async_notifier_add_subdev(&csi2dc->notifier, csi2dc->asd);
> >>> +   if (ret) {
> >>> +           dev_err(csi2dc->dev, "failed to add async notifier.\n");
> >>> +           v4l2_async_notifier_cleanup(&csi2dc->notifier);
> >>> +           goto csi2dc_prepare_notifier_err;
> >>> +   }
> >>> +
> >>> +   csi2dc->notifier.ops = &csi2dc_async_ops;
> >>> +
> >>> +   ret = v4l2_async_notifier_register(&csi2dc->v4l2_dev,
> >>> +                                      &csi2dc->notifier);
> >>> +
> >>> +   if (ret) {
> >>> +           dev_err(csi2dc->dev, "fail to register async notifier.\n");
> >>
> >> Shouldn't you cleanup the notifier if registration fails ?
> >>
> >>> +           goto csi2dc_prepare_notifier_err;
> >>> +   }
> >>> +
> >>> +csi2dc_prepare_notifier_err:
> >>> +   of_node_put(input_parent);
> >>> +
> >>> +   return ret;
> >>> +}
> >>> +
> >>> +static int csi2dc_of_parse(struct csi2dc_device *csi2dc,
> >>> +                      struct device_node *of_node)
> >>> +{
> >>> +   struct device_node *input_node, *sink_node, *input_parent;
> >>> +   struct v4l2_fwnode_endpoint input_endpoint = { 0 },
> >>> +                               sink_endpoint = { 0 };
> >>> +   int ret;
> >>> +
> >>> +   input_node = of_graph_get_next_endpoint(of_node, NULL);
> >>> +
> >>> +   if (!input_node) {
> >>> +           dev_err(csi2dc->dev,
> >>> +                   "missing port node at %s, input node is mandatory.\n",
> >>
> >> Please use %pOF to print the node name
> >> Also, input_node should be put in the error path
> >>
> >>> +                   of_node->full_name);
> >>> +           return -EINVAL;
> >>> +   }
> >>> +
> >>> +   ret = v4l2_fwnode_endpoint_parse(of_fwnode_handle(input_node),
> >>> +                                    &input_endpoint);
> >>
> >> Please set input_endpoint.bus_type if you know what kind of bus you're
> >> dealing with (not having the bindings of the IDI transmitter I'm not
> >> sure. Is this V4L2_MBUS_CSI2_DPHY ?)
> >>
> >>> +
> >>> +   if (ret) {
> >>> +           dev_err(csi2dc->dev, "endpoint not defined at %s\n",
> >>> +                   of_node->full_name);
> >>> +           return ret;
> >>> +   }
> >>> +
> >>> +   input_parent = of_graph_get_remote_port_parent(input_node);
> >>> +   if (!input_parent) {
> >>
> >> Missing of_node_put(input_node)
> >>
> >>> +           dev_err(csi2dc->dev,
> >>> +                   "could not get input node's parent node.\n");
> >>> +           return -EINVAL;
> >>> +   }
> >>> +
> >>> +   sink_node = of_graph_get_next_endpoint(of_node, input_node);
> >>> +
> >>> +   if (sink_node)
> >>> +           ret = v4l2_fwnode_endpoint_parse(of_fwnode_handle(sink_node),
> >>> +                                            &sink_endpoint);
> >>
> >> Same, set sink_endpoint.bus_type if you know it's MBUS_PARALLEL
> >>
> >>> +
> >>> +   if (!sink_node || ret) {
> >>
> >> If parsing fail you don't return an error but continue registering the
> >> notifier and potentially end up registering the async subdev for this
> >> entity even if the endpoint parsing failed.
> >>
> >>> +           dev_info(csi2dc->dev,
> >>> +                    "missing sink node at %s, data pipe available only.\n",
> >>> +                    of_node->full_name);
> >>> +   } else {
> >>> +           csi2dc->video_pipe = true;
> >>
> >> video_pipe is unused it seems
> >>
> >>> +
> >>> +           dev_dbg(csi2dc->dev, "block %s %d.%d->%d.%d video pipeline\n",
> >>> +                   of_node->full_name, input_endpoint.base.port,
> >>> +                   input_endpoint.base.id, sink_endpoint.base.port,
> >>> +                   sink_endpoint.base.id);
> >>> +   }
> >>> +
> >>> +   of_node_put(sink_node);
> >>> +   of_node_put(input_node);
> >>> +
> >>> +   /* prepare async notifier for subdevice completion */
> >>> +   return csi2dc_prepare_notifier(csi2dc, input_parent);
> >>> +}
> >>> +
> >>> +static void csi2dc_workq_handler(struct work_struct *workq)
> >>> +{
> >>> +   struct csi2dc_device *csi2dc = container_of(workq,
> >>> +                                   struct csi2dc_device, workq);
> >>> +   int ret;
> >>> +
> >>> +   if (v4l2_async_register_subdev(&csi2dc->csi2dc_sd))
> >>> +           dev_dbg(csi2dc->dev, "failed to register the subdevice\n");
> >>
> >> That's peculiar, why do you have to schedule this to a workqueue
> >> instead of doing this in the complete() callback ?
> >>
> >>> +
> >>> +   ret = csi2dc_power(csi2dc, true);
> >>> +   if (ret < 0)
> >>> +           v4l2_err(&csi2dc->v4l2_dev, "failed to power on\n");
> >>
> >> Should the device be powered on at s_stream time ? Possibly with a
> >> pm_runtime_get_sync() call ? I see you register pm_runtime operations,
> >> but never call get_sync() or _put().
> >>
> >> What if CONFIG_PM not selected ? Should this driver select it ? Do you
> >> have use cases where that's not possible ?
> >>
> >>> +}
> >>> +
> >>> +static int csi2dc_probe(struct platform_device *pdev)
> >>> +{
> >>> +   struct device *dev = &pdev->dev;
> >>> +   struct csi2dc_device *csi2dc;
> >>> +   struct resource *res = NULL;
> >>> +   int ret = 0;
> >>> +
> >>> +   csi2dc = devm_kzalloc(dev, sizeof(*csi2dc), GFP_KERNEL);
> >>> +   if (!csi2dc)
> >>> +           return -ENOMEM;
> >>> +
> >>> +   csi2dc->dev = dev;
> >>> +
> >>> +   res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> >>> +   if (!res)
> >>> +           return -EINVAL;
> >>
> >> devm_ioremap_resource() checks for the validity of 'res' so you can
> >> drop the previous two lines
> >>
> >>> +
> >>> +   csi2dc->base = devm_ioremap_resource(dev, res);
> >>> +
> >>
> >> Is the empy line intentional, sometimes you have one, sometimes you
> >> don't ?
> >>
> >>> +   if (IS_ERR(csi2dc->base)) {
> >>> +           dev_err(dev, "base address not set\n");
> >>
> >>
> >>> +           return PTR_ERR(csi2dc->base);
> >>> +   }
> >>> +
> >>> +   csi2dc->pclk = devm_clk_get(dev, "pclk");
> >>> +   if (IS_ERR(csi2dc->pclk)) {
> >>> +           ret = PTR_ERR(csi2dc->pclk);
> >>> +           dev_err(dev, "failed to get pclk: %d\n", ret);
> >>> +           return ret;
> >>
> >> Just return PTR_ERR instead of assigning to ret
> >>
> >>> +   }
> >>> +
> >>> +   ret = clk_prepare_enable(csi2dc->pclk);
> >>> +   if (ret) {
> >>> +           dev_err(dev, "failed to enable pclk: %d\n", ret);
> >>> +           return ret;
> >>> +   }
> >>
> >> Has this clock to be enabled here or can it be done in the
> >> pm_runtime callback ?
> >>
> >>> +
> >>> +   csi2dc->scck = devm_clk_get(dev, "scck");
> >>> +   if (IS_ERR(csi2dc->scck)) {
> >>> +           ret = PTR_ERR(csi2dc->scck);
> >>> +           dev_err(dev, "failed to get scck: %d\n", ret);
> >>> +           goto csi2dc_clk_fail;
> >>> +   }
> >>> +
> >>> +   ret = v4l2_device_register(dev, &csi2dc->v4l2_dev);
> >>> +   if (ret) {
> >>> +           dev_err(dev, "unable to register v4l2 device.\n");
> >>> +           goto csi2dc_clk_fail;
> >>> +   }
> >>> +
> >>> +   v4l2_subdev_init(&csi2dc->csi2dc_sd, &csi2dc_subdev_ops);
> >>> +
> >>> +   csi2dc->csi2dc_sd.owner = THIS_MODULE;
> >>> +   csi2dc->csi2dc_sd.dev = dev;
> >>> +   snprintf(csi2dc->csi2dc_sd.name, sizeof(csi2dc->csi2dc_sd.name),
> >>> +            "CSI2DC.0");
> >>> +
> >>> +   csi2dc->csi2dc_sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
> >>> +   csi2dc->csi2dc_sd.entity.function = MEDIA_ENT_F_VID_IF_BRIDGE;
> >>> +   csi2dc->pads[CSI2DC_PAD_SINK].flags = MEDIA_PAD_FL_SINK;
> >>> +   csi2dc->pads[CSI2DC_PAD_SOURCE].flags = MEDIA_PAD_FL_SOURCE;
> >>
> >> Isn't the source pad presence conditional to the presence of
> >> port@1 ?
> >>
> >>> +
> >>> +   ret = media_entity_pads_init(&csi2dc->csi2dc_sd.entity, CSI2DC_PADS_NUM,
> >>> +                                csi2dc->pads);
> >>> +   if (ret < 0) {
> >>> +           dev_err(dev, "media entity init failed\n");
> >>> +           goto csi2dc_probe_entity_err;
> >>> +   }
> >>> +
> >>> +   v4l2_set_subdevdata(&csi2dc->csi2dc_sd, pdev);
> >>> +
> >>> +   platform_set_drvdata(pdev, &csi2dc->csi2dc_sd);
> >>> +
> >>> +   INIT_WORK(&csi2dc->workq, csi2dc_workq_handler);
> >>> +
> >>> +   ret = csi2dc_of_parse(csi2dc, dev->of_node);
> >>> +   if (ret)
> >>> +           goto csi2dc_probe_entity_err;
> >>> +
> >>> +   dev_info(dev, "Microchip CSI2DC version %x\n",
> >>> +            csi2dc_readl(csi2dc, CSI2DC_VERSION));
> >>> +
> >>> +   pm_runtime_set_active(dev);
> >>> +   pm_runtime_enable(dev);
> >>> +   pm_request_idle(dev);
> >>> +
> >>> +   return 0;
> >>> +
> >>> +csi2dc_probe_entity_err:
> >>> +   media_entity_cleanup(&csi2dc->csi2dc_sd.entity);
> >>> +   v4l2_device_unregister(&csi2dc->v4l2_dev);
> >>> +csi2dc_clk_fail:
> >>> +   clk_disable_unprepare(csi2dc->pclk);
> >>> +   return ret;
> >>> +}
> >>> +
> >>> +static int csi2dc_remove(struct platform_device *pdev)
> >>> +{
> >>> +   struct v4l2_subdev *csi2dc_sd = platform_get_drvdata(pdev);
> >>> +   struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
> >>> +
> >>> +   pm_runtime_disable(&pdev->dev);
> >>> +
> >>> +   v4l2_async_unregister_subdev(&csi2dc->csi2dc_sd);
> >>> +   csi2dc_cleanup_notifier(csi2dc);
> >>> +   media_entity_cleanup(&csi2dc->csi2dc_sd.entity);
> >>> +   v4l2_device_unregister(&csi2dc->v4l2_dev);
> >>> +   clk_disable_unprepare(csi2dc->pclk);
> >>> +
> >>> +   return 0;
> >>> +}
> >>> +
> >>> +static int __maybe_unused csi2dc_runtime_suspend(struct device *dev)
> >>> +{
> >>> +   struct csi2dc_device *csi2dc = dev_get_drvdata(dev);
> >>> +
> >>> +   return csi2dc_power(csi2dc, false);
> >>> +}
> >>> +
> >>> +static int __maybe_unused csi2dc_runtime_resume(struct device *dev)
> >>> +{
> >>> +   struct csi2dc_device *csi2dc = dev_get_drvdata(dev);
> >>> +
> >>> +   return csi2dc_power(csi2dc, true);
> >>> +}
> >>> +
> >>> +static const struct dev_pm_ops csi2dc_dev_pm_ops = {
> >>> +   SET_RUNTIME_PM_OPS(csi2dc_runtime_suspend, csi2dc_runtime_resume, NULL)
> >>> +};
> >>> +
> >>> +static const struct of_device_id csi2dc_of_match[] = {
> >>> +   { .compatible = "microchip,sama7g5-csi2dc" },
> >>> +   { }
> >>> +};
> >>> +
> >>> +MODULE_DEVICE_TABLE(of, csi2dc_of_match);
> >>> +
> >>> +static struct platform_driver csi2dc_driver = {
> >>> +   .probe  = csi2dc_probe,
> >>> +   .remove = csi2dc_remove,
> >>> +   .driver = {
> >>> +           .name           = "microchip-csi2dc",
> >>> +           .pm             = &csi2dc_dev_pm_ops,
> >>> +           .of_match_table = of_match_ptr(csi2dc_of_match),
> >>> +   },
> >>> +};
> >>> +
> >>> +module_platform_driver(csi2dc_driver);
> >>> +
> >>> +MODULE_AUTHOR("Eugen Hristev <eugen.hristev@microchip.com>");
> >>> +MODULE_DESCRIPTION("Microchip CSI2 Demux Controller driver");
> >>> +MODULE_LICENSE("GPL v2");
> >>> +MODULE_SUPPORTED_DEVICE("video");
> >>
> >> For my education, what's MODULE_SUPPORTED_DEVICE for ?
> >
> > It's "not yet implemented" since 2005, I think it can be dropped :-)
> >
> > --
> > Regards,
> >
> > Laurent Pinchart
> >
>

Re: [PATCH v5 2/3] media: atmel: introduce microchip csi2dc driver

[Eugen.Hristev]

On 18.11.2020 11:11, Jacopo Mondi wrote:
> Hello Eugen,
> 
> On Tue, Nov 17, 2020 at 05:24:30PM +0000, Eugen.Hristev@microchip.com wrote:
>> On 17.11.2020 14:09, Laurent Pinchart wrote:
>>> Hello everybody,
>>>
>>> On Tue, Nov 17, 2020 at 12:59:02PM +0100, Jacopo Mondi wrote:
>>>> On Thu, Nov 12, 2020 at 03:34:36PM +0200, Eugen Hristev wrote:
>>>>> Microchip CSI2DC (CSI2 Demultiplexer Controller) is a misc bridge device
>>>>> that converts a byte stream in IDI Synopsys format (coming from a CSI2HOST)
>>>>> to a pixel stream that can be captured by a sensor controller.
>>>>>
>>>>> Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
>>>>> ---
>>>>> Hello,
>>>>>
>>>>> There still are some open questions regarding the last reviews on the ML.
>>>>>
>>>>> Regarding the format list which is not const, I cannot have it const because
>>>>> I reference elements from this list into a dynamic list which is non-const.
>>>>>
>>>>> Regarding the presence of the v4l2_dev, without this I cannot add a notifier
>>>>> for this device to have it async completed , when the underlying subdevice
>>>>> finishes probing.
>>>>
>>>> I see you have a discussion with Sakari on-going on this, and I have
>>>> the very same comment he had.
>>>>
>>>> Should a sub-notifier be used and this driver should not register any
>>>> v4l2_dev but integrate in the media graph of the receiver ?
>>>>
>>>> For reference, rcar-csi2 uses sub-notifiers and register in the
>>>> rcar-vin media graph, it doesn't need to set up a v4l2_dev.
>>>>
>>>> rcar-vin (the DMA engine driver) that register video nodes and the v4l2-dev
>>>> also registers the device nodes for all the connected subdevices.
>>>
>>> Sub-notifiers were invited for this purpose, so I think they're the
>>> right tool.
>>>
>>>>> Regarding the callbacks for set frame interval, set frame size, etc, I cannot
>>>>> remove them because losing functionality to the underlying subdevice, as
>>>>> explained in :
>>>>> https://lkml.org/lkml/2020/10/12/427
>>>>
>>>> Using the frame sizes as in the example you reported, if this device has
>>>> limitations on the supported sizes, (a min and a max most
>>>> probably) that's the only thing that should be exposed from this
>>>> driver subdevice. The sensor subdevice instead will report the
>>>> available discrete sizes and userspace configures the sensor's source
>>>> pad and the bridge's sink pad with the same sizes to properly set up the
>>>> capture pipeline. video0 should not report the sizes exposed by the sensor
>>>> nor any information that depends on what's connected to it.
>>>
>>> Agreed. Subdev drivers should remain simple and cover only the subdev
>>> they manage. Bundling it together is the job of userspace. In the legacy
>>> model it uses to be the job of the top-level V4L2 driver (the one
>>> implementing v4l2_device), but that's legacy, especially for embedded
>>> camera use cases. In any case, the top-level logic must not be spread
>>> across subdevices.
>>>
>>>> I know what your next question is: what about existing application
>>>> that only know about video0 and want to setup everything from there. I
>>>> understand vendors not wanting to wrap gstreamer or what is used in
>>>> the wild in custom scripts that sets up the pipeline opportunely
>>>> before streaming, and I'm pretty sure you know what is the solution I
>>>> would propose for this :)
>>>>
>>>> I've just gone through the same path with RPi's Unicam, that does the
>>>> same thing as your one does: it's an MC driver, but wants to control
>>>> the sensor through the v4l2-subdev kAPI to support legacy use cases
>>>> not covered by libcamera. The fact is that we're stuck in this limbo
>>>> where MC pipeline tries to decouple components one from each other and
>>>> delegate their configuration to userspace, but at the same time
>>>> vendors want to be able to use the simple plain video node centric
>>>> interface because of their existing user base, so I understand your
>>>> discomfort, but the 'simple plain' approach is what's preventing Linux
>>>> platforms to be in-par with proprietary and custom solutions for any
>>>> use case that is not a simple frame capture, so I think it's fair for
>>>> mainline to push for this evolution to happen. Just my2c of course.
>>>
>>> Compatibility with the userspace of downstream kernels is important, but
>>> that's a downstream kernel issue. In mainline we want to go the MC way,
>>> and downstream can then, if desired, implement the configuration of the
>>> pipeline in the top-level V4L2 driver in the kernel to support the
>>> existing userbase. For new drivers I wouldn't recommend that, for
>>> existing downstream drivers it may be required.
>>
>> Hello,
>>
>> First of all thank you for the review and explanations.
>>
>> I am still confused about how does the userspace know which elements are
>> in the pipeline and how to connect them ?
> 
> Using the media-controller uAPI to inspect, explore and configure the
> media graph (it's mostly about enabling and disabling media links),
> and using the v4l2 subdev uAPI to configure formats, sizes and such on
> each subdevice device node associated with a media entity. Finally,
> using the v4l2 uAPI to stream from the top-level driver that expose a
> video device node.

Okay but which application in userspace uses this userAPI ?
So I could use it to test my pipeline.

> 
> It's really (conceptually) not different than doing the same using
> media-ctl and v4l2-ctl.
> 
>> And if this is the case, what is the purpose of the endpoints in the DT ?
>>
> 
> DTS describe the hardware. Usually a driver parses the firmware graph
> to create and model the media graph and the available connections
> between media entities but there's no requirement to have a 1-to-1
> match (as far I'm aware).

So the top level v4l2 driver should parse the whole graph ?

> 
> Media links on a media graph then need to be enabled opportunely
> depending on the desired use case, the platform topology etc
> 
>> At this moment, I just use the /dev/video0, because the top v4l2 driver
>> configures the subdevice, and this subdevice configures it's own
>> subdevice and so on, until the sensor itself.
>>
>> My top v4l2 driver will not 'complete' unless a subdevice registers
>> itself , and if this subdevice does not provide any information
>> regarding its formats, the probe of the top v4l2 driver will fail,
>> because it will not find compatibility between it's supported input
>> formats and what the subdevice provides.
> 
> ouch, I see.. Which driver is that ?

The atmel image sensor controller driver.
All sensor drivers that we use (for example : ov5640, ov7740, ov7670) 
register as subdevices, and the atmel-isc will 'complete' when the 
sensor is probed and registered.
To have the csi2dc module compatible with what we have on atmel-isc, 
it's natural to have the csi2dc register itself as a subdevice such that 
the atmel-isc can 'complete'.


> 
> If that's an MC driver, and that seems the case, it should not bother
> validating the subdevice formats, but only care about listing what its
> capabilities are.

if this atmel-isc does not offer format capabilities for the userspace 
via the /dev/video0, then all applications that we use (gstreamer 
v4l2src, ffmpeg ) fail.
What can we use then, if we cannot use these applications ?

> 
>>
>> So what to do in this case ? Libcamera will configure this whole
>> pipeline for me , if the drivers just probe ( and start/stop streaming
>> by selecting the respective registers) ? or how to do this whole
>> pipeline configuration ?
>>
> 
> Well, libcamera offers a framework to enable specialized code (called
> "pipeline handler") to operate under an high-level API towards application
> and implement image tuning algorithms on top of that common API.
> 
> The code to configure the pipeline is device specific (unless your
> pipeline is very simple). So it's not that libcamera just magically
> knows how to operate on every platforms it runs on, it needs platform
> specific code to do so. What you get in exchange is an high level API
> to offer to application developers, a framework to implement 3A and
> tuning algorithms, integration with a growing set of other userspace
> frameworks (android, gstreamer, pipewire and a legacy v4l2-compat
> layer)

I tried a buildroot with libcamera and gstreamer libcamerasrc , to see 
how it goes. Libcamera does not recognize the /dev/video0 device that we 
have. The v4l2 compatibility layer should not perform exactly this ?

# gst-launch-1.0 libcamerasrc ! fakesink
Setting pipeline to PAUSED ...
[0:00:28.448687200] [216]  WARN IPAManager ipa_manager.cpp:147 No IPA 
found in '/usr/lib/libcamera'
[0:00:28.448890800] [216]  INFO Camera camera_manager.cpp:287 libcamera 
v0.0.0+54328-2020.11-rc2-dirty (2020-11-17T20:58:37+02:00)
ERROR: from element 
/GstPipeline:pipeline0/GstLibcameraSrc:libcamerasrc0: Could not find any 
supported camera on this system.
Additional debug info:
../src/gstreamer/gstlibcamerasrc.cpp(236): gst_libcamera_src_open (): 
/GstPipeline:pipeline0/GstLibcameraSrc:libcamerasrc0:
libcamera::CameraMananger::cameras() is empty
ERROR: pipeline doesn't want to preroll.
Failed to set pipeline to PAUSED.
Setting pipeline to NULL ...
Freeing pipeline ...


Thanks,
Eugen

> 
> We have a lengthy pipeline handler writers guide that might help
> better explain this:
> 
> https://git.linuxtv.org/libcamera.git/tree/Documentation/guides/pipeline-handler.rst
> (you might want to compile libcamera to be able to render it in a browser)
> 
> Hope this helps to clarify things a bit
> 
>>
>>>
>>>> Some more comments on the implementation below
>>>>
>>>>> Changes in v5:
>>>>> - only in bindings
>>>>>
>>>>> Changes in v4:
>>>>> - now using get_mbus_config ops to get data from the subdevice, like the
>>>>> virtual channel id, and the clock type.
>>>>> - now having possibility to select any of the RAW10 data modes
>>>>> - at completion time, select which formats are also available in the subdevice,
>>>>> and move to the dynamic list accordingly
>>>>> - changed the pipeline integration, do not advertise subdev ready at probe time.
>>>>> wait until completion is done, and then start a workqueue that will register
>>>>> this device as a subdevice for the next element in pipeline.
>>>>> - moved the s_power code into a different function called now csi2dc_power
>>>>> that is called with CONFIG_PM functions. This is also called at completion,
>>>>> to have the device ready in case CONFIG_PM is not selected on the platform.
>>>>> - merged try_fmt into set_fmt
>>>>> - driver cleanup, wrapped lines over 80 characters
>>>>>
>>>>> Changes in v2:
>>>>> - moved driver to platform/atmel
>>>>> - fixed minor things as per Sakari's review
>>>>> - still some things from v2 review are not yet addressed, to be followed up
>>>>>
>>>>>    drivers/media/platform/atmel/Kconfig          |  13 +
>>>>>    drivers/media/platform/atmel/Makefile         |   1 +
>>>>>    .../media/platform/atmel/microchip-csi2dc.c   | 785 ++++++++++++++++++
>>>>>    3 files changed, 799 insertions(+)
>>>>>    create mode 100644 drivers/media/platform/atmel/microchip-csi2dc.c
>>>>>
>>>>> diff --git a/drivers/media/platform/atmel/Kconfig b/drivers/media/platform/atmel/Kconfig
>>>>> index 99b51213f871..147e1c14129b 100644
>>>>> --- a/drivers/media/platform/atmel/Kconfig
>>>>> +++ b/drivers/media/platform/atmel/Kconfig
>>>>> @@ -32,3 +32,16 @@ config VIDEO_ATMEL_ISI
>>>>>       help
>>>>>         This module makes the ATMEL Image Sensor Interface available
>>>>>         as a v4l2 device.
>>>>> +
>>>>> +config VIDEO_MICROCHIP_CSI2DC
>>>>> +   tristate "Microchip CSI2 Demux Controller"
>>>>> +   depends on VIDEO_V4L2 && COMMON_CLK && OF
>>>>> +   depends on ARCH_AT91 || COMPILE_TEST
>>>>> +   select MEDIA_CONTROLLER
>>>>> +   select VIDEO_V4L2_SUBDEV_API
>>>>> +   select V4L2_FWNODE
>>>>> +   help
>>>>> +     CSI2 Demux Controller driver. CSI2DC is a helper chip
>>>>> +     that converts IDI interface byte stream to a parallel pixel stream.
>>>>> +     It supports various RAW formats as input.
>>>>> +     Performs clock domain crossing between hardware blocks.
>>>>
>>>> Is the last phrase necessary ? Also missing the usual
>>>>
>>>>           To compile this driver as a module, choose M here: the
>>>>           module will be called ...
>>>>
>>>>> diff --git a/drivers/media/platform/atmel/Makefile b/drivers/media/platform/atmel/Makefile
>>>>> index c5c01556c653..8e80af500bf5 100644
>>>>> --- a/drivers/media/platform/atmel/Makefile
>>>>> +++ b/drivers/media/platform/atmel/Makefile
>>>>> @@ -5,3 +5,4 @@ atmel-xisc-objs = atmel-sama7g5-isc.o atmel-isc-base.o
>>>>>    obj-$(CONFIG_VIDEO_ATMEL_ISI) += atmel-isi.o
>>>>>    obj-$(CONFIG_VIDEO_ATMEL_ISC) += atmel-isc.o
>>>>>    obj-$(CONFIG_VIDEO_ATMEL_XISC) += atmel-xisc.o
>>>>> +obj-$(CONFIG_VIDEO_MICROCHIP_CSI2DC) += microchip-csi2dc.o
>>>>> diff --git a/drivers/media/platform/atmel/microchip-csi2dc.c b/drivers/media/platform/atmel/microchip-csi2dc.c
>>>>> new file mode 100644
>>>>> index 000000000000..fda1d5882dbb
>>>>> --- /dev/null
>>>>> +++ b/drivers/media/platform/atmel/microchip-csi2dc.c
>>>>> @@ -0,0 +1,785 @@
>>>>> +// SPDX-License-Identifier: GPL-2.0
>>>>
>>>> Nit: I see GPL-2.0 listed as deprecated by spdx.org
>>>> Should you use one of:
>>>>                 GPL-2.0-only
>>>>                         GPL-2.0-or-later
>>>>
>>>>> +/*
>>>>> + * Microchip CSI2 Demux Controller (CSI2DC) driver
>>>>> + *
>>>>> + * Copyright (C) 2018-2020 Microchip Technology, Inc.
>>>>> + *
>>>>> + * Author: Eugen Hristev <eugen.hristev@microchip.com>
>>>>> + *
>>>>> + */
>>>>> +
>>>>> +#include <linux/clk.h>
>>>>> +#include <linux/module.h>
>>>>> +#include <linux/of.h>
>>>>> +#include <linux/of_graph.h>
>>>>> +#include <linux/platform_device.h>
>>>>> +#include <linux/pm_runtime.h>
>>>>> +#include <linux/videodev2.h>
>>>>> +
>>>>> +#include <media/v4l2-device.h>
>>>>> +#include <media/v4l2-fwnode.h>
>>>>> +#include <media/v4l2-subdev.h>
>>>>> +#include <media/videobuf2-dma-contig.h>
>>>>> +
>>>>> +/* Global configuration register */
>>>>> +#define CSI2DC_GCFG                        0x0
>>>>> +
>>>>> +/* MIPI sensor pixel clock is free running */
>>>>> +#define CSI2DC_GCFG_MIPIFRN                BIT(0)
>>>>> +/* Output waveform inter-line minimum delay */
>>>>> +#define CSI2DC_GCFG_HLC(v)         ((v) << 4)
>>>>> +#define CSI2DC_GCFG_HLC_MASK               GENMASK(7, 4)
>>>>> +/* SAMA7G5 requires a HLC delay of 15 */
>>>>> +#define SAMA7G5_HLC                        (15)
>>>>> +
>>>>> +/* Global control register */
>>>>> +#define CSI2DC_GCTLR                       0x04
>>>>> +#define CSI2DC_GCTLR_SWRST         BIT(0)
>>>>> +
>>>>> +/* Global status register */
>>>>> +#define CSI2DC_GS                  0x08
>>>>> +
>>>>> +/* SSP interrupt status register */
>>>>> +#define CSI2DC_SSPIS                       0x28
>>>>> +/* Pipe update register */
>>>>> +#define CSI2DC_PU                  0xC0
>>>>> +/* Video pipe attributes update */
>>>>> +#define CSI2DC_PU_VP                       BIT(0)
>>>>> +
>>>>> +/* Pipe update status register */
>>>>> +#define CSI2DC_PUS                 0xC4
>>>>> +
>>>>> +/* Video pipeline enable register */
>>>>> +#define CSI2DC_VPE                 0xF8
>>>>> +#define CSI2DC_VPE_ENABLE          BIT(0)
>>>>> +
>>>>> +/* Video pipeline configuration register */
>>>>> +#define CSI2DC_VPCFG                       0xFC
>>>>> +/* Data type */
>>>>> +#define CSI2DC_VPCFG_DT(v)         ((v) << 0)
>>>>> +#define CSI2DC_VPCFG_DT_MASK               GENMASK(5, 0)
>>>>> +/* Virtual channel identifier */
>>>>> +#define CSI2DC_VPCFG_VC(v)         ((v) << 6)
>>>>> +#define CSI2DC_VPCFG_VC_MASK               GENMASK(7, 6)
>>>>> +/* Decompression enable */
>>>>> +#define CSI2DC_VPCFG_DE                    BIT(8)
>>>>> +/* Decoder mode */
>>>>> +#define CSI2DC_VPCFG_DM(v)         ((v) << 9)
>>>>> +#define CSI2DC_VPCFG_DM_DECODER8TO12       0
>>>>> +/* Decoder predictor 2 selection */
>>>>> +#define CSI2DC_VPCFG_DP2           BIT(12)
>>>>> +/* Recommended memory storage */
>>>>> +#define CSI2DC_VPCFG_RMS           BIT(13)
>>>>> +/* Post adjustment */
>>>>> +#define CSI2DC_VPCFG_PA                    BIT(14)
>>>>> +
>>>>> +/* Video pipeline column register */
>>>>> +#define CSI2DC_VPCOL                       0x100
>>>>> +/* Column number */
>>>>> +#define CSI2DC_VPCOL_COL(v)                ((v) << 0)
>>>>> +#define CSI2DC_VPCOL_COL_MASK              GENMASK(15, 0)
>>>>> +
>>>>> +/* Video pipeline row register */
>>>>> +#define CSI2DC_VPROW                       0x104
>>>>> +/* Row number */
>>>>> +#define CSI2DC_VPROW_ROW(v)                ((v) << 0)
>>>>> +#define CSI2DC_VPROW_ROW_MASK              GENMASK(15, 0)
>>>>> +
>>>>> +/* Version register */
>>>>> +#define CSI2DC_VERSION                     0x1FC
>>>>> +
>>>>> +/* register read/write helpers */
>>>>> +#define csi2dc_readl(st, reg)              readl_relaxed((st)->base + (reg))
>>>>> +#define csi2dc_writel(st, reg, val)        writel_relaxed((val), \
>>>>> +                                   (st)->base + (reg))
>>>>> +
>>>>> +/* supported RAW data types */
>>>>> +#define CSI2DC_DT_RAW6                     0x28
>>>>> +#define CSI2DC_DT_RAW7                     0x29
>>>>> +#define CSI2DC_DT_RAW8                     0x2A
>>>>> +#define CSI2DC_DT_RAW10                    0x2B
>>>>> +#define CSI2DC_DT_RAW12                    0x2C
>>>>> +#define CSI2DC_DT_RAW14                    0x2D
>>>>> +
>>>>> +struct csi2dc_format {
>>>>> +   u32                             mbus_code;
>>>>> +   u32                             dt;
>>>>> +};
>>>>> +
>>>>> +static struct csi2dc_format csi2dc_formats_list[] = {
>>>>> +   {
>>>>> +           .mbus_code =            MEDIA_BUS_FMT_SRGGB10_1X10,
>>>>> +           .dt =                   CSI2DC_DT_RAW10,
>>>>> +   }, {
>>>>> +           .mbus_code =            MEDIA_BUS_FMT_SBGGR10_1X10,
>>>>> +           .dt =                   CSI2DC_DT_RAW10,
>>>>> +   }, {
>>>>> +           .mbus_code =            MEDIA_BUS_FMT_SGRBG10_1X10,
>>>>> +           .dt =                   CSI2DC_DT_RAW10,
>>>>> +   }, {
>>>>> +           .mbus_code =            MEDIA_BUS_FMT_SGBRG10_1X10,
>>>>> +           .dt =                   CSI2DC_DT_RAW10,
>>>>> +   },
>>>>> +};
>>>>> +
>>>>> +enum mipi_csi_pads {
>>>>> +   CSI2DC_PAD_SINK                 = 0,
>>>>> +   CSI2DC_PAD_SOURCE               = 1,
>>>>> +   CSI2DC_PADS_NUM                 = 2,
>>>>> +};
>>>>> +
>>>>> +struct csi2dc_device {
>>>>> +   void __iomem                    *base;
>>>>> +   struct v4l2_subdev              csi2dc_sd;
>>>>> +   struct device                   *dev;
>>>>> +   struct v4l2_device              v4l2_dev;
>>>>> +   struct clk                      *pclk;
>>>>> +   struct clk                      *scck;
>>>>> +
>>>>> +   bool                            video_pipe;
>>>>> +
>>>>> +   u32                             num_fmts;
>>>>> +   struct csi2dc_format            **formats;
>>>>> +
>>>>> +   struct csi2dc_format            *cur_fmt;
>>>>> +   struct csi2dc_format            *try_fmt;
>>>>> +
>>>>> +   struct media_pad                pads[CSI2DC_PADS_NUM];
>>>>> +
>>>>> +   bool                            clk_gated;
>>>>> +   u32                             vc;
>>>>> +
>>>>> +   struct v4l2_async_subdev        *asd;
>>>>> +   struct v4l2_async_notifier      notifier;
>>>>> +
>>>>> +   struct v4l2_subdev              *input_sd;
>>>>> +
>>>>> +   u32                             remote_pad;
>>>>> +
>>>>> +   bool                            completed;
>>>>> +   bool                            powered_on;
>>>>> +
>>>>> +   struct work_struct              workq;
>>>>> +};
>>>>> +
>>>>> +static void csi2dc_vp_update(struct csi2dc_device *csi2dc)
>>>>> +{
>>>>> +   u32 vp;
>>>>> +
>>>>> +   vp = CSI2DC_VPCFG_DT(csi2dc->cur_fmt->dt) & CSI2DC_VPCFG_DT_MASK;
>>>>> +   vp |= CSI2DC_VPCFG_VC(csi2dc->vc) & CSI2DC_VPCFG_VC_MASK;
>>>>> +   vp &= ~CSI2DC_VPCFG_DE;
>>>>> +   vp |= CSI2DC_VPCFG_DM(CSI2DC_VPCFG_DM_DECODER8TO12);
>>>>> +   vp &= ~CSI2DC_VPCFG_DP2;
>>>>> +   vp &= ~CSI2DC_VPCFG_RMS;
>>>>> +   vp |= CSI2DC_VPCFG_PA;
>>>>> +
>>>>> +   csi2dc_writel(csi2dc, CSI2DC_VPCFG, vp);
>>>>> +   csi2dc_writel(csi2dc, CSI2DC_VPE, CSI2DC_VPE_ENABLE);
>>>>> +   csi2dc_writel(csi2dc, CSI2DC_PU, CSI2DC_PU_VP);
>>>>> +}
>>>>> +
>>>>> +static inline struct csi2dc_device *
>>>>> +csi2dc_sd_to_csi2dc_device(struct v4l2_subdev *csi2dc_sd)
>>>>> +{
>>>>> +   return container_of(csi2dc_sd, struct csi2dc_device, csi2dc_sd);
>>>>> +}
>>>>> +
>>>>> +static int csi2dc_enum_mbus_code(struct v4l2_subdev *csi2dc_sd,
>>>>> +                            struct v4l2_subdev_pad_config *cfg,
>>>>> +                            struct v4l2_subdev_mbus_code_enum *code)
>>>>> +{
>>>>> +   struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
>>>>> +
>>>>> +   if (code->index >= csi2dc->num_fmts)
>>>>> +           return -EINVAL;
>>>>> +
>>>>> +   code->code = csi2dc->formats[code->index]->mbus_code;
>>>>> +   return 0;
>>>>> +}
>>>>> +
>>>>> +static int csi2dc_set_fmt(struct v4l2_subdev *csi2dc_sd,
>>>>> +                     struct v4l2_subdev_pad_config *cfg,
>>>>> +                     struct v4l2_subdev_format *req_fmt)
>>>>> +{
>>>>> +   struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
>>>>> +   struct csi2dc_format *fmt;
>>>>> +   int ret, i;
>>>>> +
>>>>> +   if (!csi2dc->completed) {
>>>>> +           dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
>>>>> +           return 0;
>>>>> +   }
>>>>> +
>>>>> +   for (fmt = csi2dc->formats[0], i = 0; i < csi2dc->num_fmts; fmt++, i++)
>>>>> +           if (req_fmt->format.code == fmt->mbus_code)
>>>>> +                   csi2dc->try_fmt = fmt;
>>>>> +
>>>>> +   /* in case we could not find the desired format, default to something */
>>>>> +   if (!csi2dc->try_fmt  ||
>>>>> +       req_fmt->format.code != csi2dc->try_fmt->mbus_code) {
>>>>> +           csi2dc->try_fmt = csi2dc->formats[0];
>>>>> +
>>>>> +           dev_dbg(csi2dc->dev,
>>>>> +                   "CSI2DC unsupported format 0x%x, defaulting to 0x%x\n",
>>>>> +                   req_fmt->format.code, csi2dc->formats[0]->mbus_code);
>>>>> +
>>>>> +           req_fmt->format.code = csi2dc->formats[0]->mbus_code;
>>>>> +   }
>>>>> +
>>>>> +   /* if we are just trying, we are done */
>>>>> +   if (req_fmt->which == V4L2_SUBDEV_FORMAT_TRY)
>>>>> +           return 0;
>>>>> +
>>>>> +   ret = v4l2_subdev_call(csi2dc->input_sd, pad, set_fmt, cfg, req_fmt);
>>>>> +   if (ret) {
>>>>> +           dev_err(csi2dc->dev, "input subdev failed %d\n", ret);
>>>>> +           return ret;
>>>>> +   }
>>>>> +
>>>>> +   csi2dc->cur_fmt = csi2dc->try_fmt;
>>>>> +   /* update video pipe */
>>>>> +   csi2dc_vp_update(csi2dc);
>>>>> +
>>>>> +   dev_dbg(csi2dc->dev, "CSI2DC new format: 0x%x\n", req_fmt->format.code);
>>>>> +   return 0;
>>>>> +}
>>>>> +
>>>>> +static int csi2dc_formats_init(struct csi2dc_device *csi2dc)
>>>>> +{
>>>>> +   struct csi2dc_format *fmt;
>>>>> +   struct v4l2_subdev *subdev = csi2dc->input_sd;
>>>>> +   unsigned int num_fmts, i;
>>>>> +
>>>>> +   struct v4l2_subdev_mbus_code_enum mbus_code = {
>>>>> +           .which = V4L2_SUBDEV_FORMAT_ACTIVE,
>>>>> +           .index = 0,
>>>>> +   };
>>>>> +
>>>>> +   num_fmts = 0;
>>>>> +
>>>>> +   csi2dc->formats = devm_kcalloc(csi2dc->dev,
>>>>> +                                  ARRAY_SIZE(csi2dc_formats_list),
>>>>> +                                  sizeof(*csi2dc->formats), GFP_KERNEL);
>>>>> +   if (!csi2dc->formats)
>>>>> +           return -ENOMEM;
>>>>> +
>>>>> +   while (!v4l2_subdev_call(subdev, pad, enum_mbus_code, NULL,
>>>>> +          &mbus_code)) {
>>>>> +           mbus_code.index++;
>>>>> +           for (fmt = &csi2dc_formats_list[0], i = 0;
>>>>> +                i < ARRAY_SIZE(csi2dc_formats_list); i++, fmt++)
>>>>> +                   if (fmt->mbus_code == mbus_code.code) {
>>>>> +                           csi2dc->formats[num_fmts] = fmt;
>>>>> +                           num_fmts++;
>>>>> +                   }
>>>>> +   }
>>>>
>>>> For the reasons explained above and by Sakari, I think this should be dropped
>>>>
>>>>> +
>>>>> +   if (!num_fmts)
>>>>> +           return -ENXIO;
>>>>> +
>>>>> +   csi2dc->num_fmts = num_fmts;
>>>>> +
>>>>> +   return 0;
>>>>> +}
>>>>> +
>>>>> +static int csi2dc_power(struct csi2dc_device *csi2dc, int on)
>>>>> +{
>>>>> +   int ret = 0;
>>>>> +
>>>>> +   if (!csi2dc->completed) {
>>>>> +           dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
>>>>> +           return 0;
>>>>> +   }
>>>>
>>>> Can this happen ?
>>>>
>>>>> +
>>>>> +   if (csi2dc->powered_on == on)
>>>>> +           return 0;
>>>>
>>>> Same question
>>>>
>>>>> +
>>>>> +   if (on)
>>>>> +           ret = clk_prepare_enable(csi2dc->scck);
>>>>> +   else
>>>>> +           clk_disable_unprepare(csi2dc->scck);
>>>>> +   if (ret)
>>>>> +           dev_err(csi2dc->dev, "failed to enable scck: %d\n", ret);
>>>>> +
>>>>> +   /* if powering up, deassert reset line */
>>>>> +   if (on)
>>>>> +           csi2dc_writel(csi2dc, CSI2DC_GCTLR, CSI2DC_GCTLR_SWRST);
>>>>> +
>>>>> +   /* if powering down, assert reset line */
>>>>> +   if (!on)
>>>>> +           csi2dc_writel(csi2dc, CSI2DC_GCTLR, !CSI2DC_GCTLR_SWRST);
>>>>> +   if (!ret)
>>>>> +           csi2dc->powered_on = on;
>>>>
>>>> Wouldn't this be better coded as
>>>>
>>>>           if (on) {
>>>>                   clk_prepare_enable
>>>>                   csi2dc_writel(SWRST)
>>>>                   powered_on = true
>>>>           } else {
>>>>                   clk_disable_unrepare
>>>>                   csi2dc_writel(!SWRST)
>>>>                   powered_on = false
>>>>           }
>>>>> +
>>>>> +   return ret;
>>>>> +}
>>>>> +
>>>>> +static int csi2dc_s_stream(struct v4l2_subdev *csi2dc_sd, int enable)
>>>>> +{
>>>>> +   struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
>>>>> +
>>>>> +   if (!csi2dc->completed) {
>>>>> +           dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
>>>>> +           return 0;
>>>>> +   }
>>>>> +
>>>>> +   return v4l2_subdev_call(csi2dc->input_sd, video, s_stream, enable);
>>>>> +}
>>>>> +
>>>>> +static int csi2dc_g_frame_interval(struct v4l2_subdev *csi2dc_sd,
>>>>> +                              struct v4l2_subdev_frame_interval *interval)
>>>>> +{
>>>>> +   struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
>>>>> +
>>>>> +   if (!csi2dc->completed) {
>>>>> +           dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
>>>>> +           return 0;
>>>>> +   }
>>>>> +
>>>>> +   return v4l2_subdev_call(csi2dc->input_sd, video, g_frame_interval,
>>>>> +                           interval);
>>>>> +}
>>>>> +
>>>>> +static int csi2dc_s_frame_interval(struct v4l2_subdev *csi2dc_sd,
>>>>> +                              struct v4l2_subdev_frame_interval *interval)
>>>>> +{
>>>>> +   struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
>>>>> +
>>>>> +   if (!csi2dc->completed) {
>>>>> +           dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
>>>>> +           return 0;
>>>>> +   }
>>>>> +
>>>>> +   return v4l2_subdev_call(csi2dc->input_sd, video, s_frame_interval,
>>>>> +                           interval);
>>>>> +}
>>>>> +
>>>>> +static int csi2dc_enum_frame_size(struct v4l2_subdev *csi2dc_sd,
>>>>> +                             struct v4l2_subdev_pad_config *cfg,
>>>>> +                             struct v4l2_subdev_frame_size_enum *fse)
>>>>> +{
>>>>> +   struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
>>>>> +
>>>>> +   if (!csi2dc->completed) {
>>>>> +           dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
>>>>> +           return 0;
>>>>> +   }
>>>>> +
>>>>> +   return v4l2_subdev_call(csi2dc->input_sd, pad, enum_frame_size, cfg,
>>>>> +                           fse);
>>>>> +}
>>>>> +
>>>>> +static int csi2dc_enum_frame_interval(struct v4l2_subdev *csi2dc_sd,
>>>>> +                         struct v4l2_subdev_pad_config *cfg,
>>>>> +                         struct v4l2_subdev_frame_interval_enum *fie)
>>>>> +{
>>>>> +   struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
>>>>> +
>>>>> +   if (!csi2dc->completed) {
>>>>> +           dev_dbg((csi2dc)->dev, "subdev not registered yet\n");
>>>>> +           return 0;
>>>>> +   }
>>>>> +
>>>>> +   return v4l2_subdev_call(csi2dc->input_sd, pad, enum_frame_interval, cfg,
>>>>> +                           fie);
>>>>> +}
>>>>> +
>>>>> +static const struct v4l2_subdev_pad_ops csi2dc_pad_ops = {
>>>>> +   .enum_mbus_code = csi2dc_enum_mbus_code,
>>>>> +   .set_fmt = csi2dc_set_fmt,
>>>>> +   .enum_frame_size = csi2dc_enum_frame_size,
>>>>> +   .enum_frame_interval = csi2dc_enum_frame_interval,
>>>>> +};
>>>>> +
>>>>> +static const struct v4l2_subdev_video_ops csi2dc_video_ops = {
>>>>> +   .s_stream = csi2dc_s_stream,
>>>>> +   .g_frame_interval = csi2dc_g_frame_interval,
>>>>> +   .s_frame_interval = csi2dc_s_frame_interval,
>>>>> +};
>>>>> +
>>>>> +static const struct v4l2_subdev_ops csi2dc_subdev_ops = {
>>>>> +   .pad = &csi2dc_pad_ops,
>>>>> +   .video = &csi2dc_video_ops,
>>>>> +};
>>>>> +
>>>>> +static int csi2dc_get_mbus_config(struct csi2dc_device *csi2dc)
>>>>> +{
>>>>> +   struct v4l2_mbus_config mbus_config = { 0 };
>>>>> +   int ret;
>>>>> +
>>>>> +   ret = v4l2_subdev_call(csi2dc->input_sd, pad, get_mbus_config,
>>>>> +                          csi2dc->remote_pad, &mbus_config);
>>>>> +   if (ret == -ENOIOCTLCMD) {
>>>>> +           dev_dbg(csi2dc->dev,
>>>>> +                   "no remote mbus configuration available\n");
>>>>> +           goto csi2dc_get_mbus_config_defaults;
>>>>> +   }
>>>>> +
>>>>> +   if (ret) {
>>>>> +           dev_err(csi2dc->dev,
>>>>> +                   "failed to get remote mbus configuration\n");
>>>>> +           goto csi2dc_get_mbus_config_defaults;
>>>>
>>>> This should probably be an error reported to the caller. But this
>>>> function return value is not checked, so it's probably fine.
>>>>
>>>>> +   }
>>>>> +
>>>>> +   if (mbus_config.flags & V4L2_MBUS_CSI2_CHANNEL_0)
>>>>> +           csi2dc->vc = 0;
>>>>> +   else if (mbus_config.flags & V4L2_MBUS_CSI2_CHANNEL_1)
>>>>> +           csi2dc->vc = 1;
>>>>> +   else if (mbus_config.flags & V4L2_MBUS_CSI2_CHANNEL_2)
>>>>> +           csi2dc->vc = 2;
>>>>> +   else if (mbus_config.flags & V4L2_MBUS_CSI2_CHANNEL_3)
>>>>> +           csi2dc->vc = 3;
>>>>> +
>>>>> +   dev_dbg(csi2dc->dev, "subdev sending on channel %d\n", csi2dc->vc);
>>>>> +
>>>>> +   csi2dc->clk_gated = mbus_config.flags &
>>>>> +                       V4L2_MBUS_CSI2_NONCONTINUOUS_CLOCK;
>>>>> +
>>>>> +   dev_dbg(csi2dc->dev, "%s clock\n",
>>>>> +           csi2dc->clk_gated ? "gated" : "free running");
>>>>> +
>>>>> +   return 0;
>>>>> +
>>>>> +csi2dc_get_mbus_config_defaults:
>>>>> +   csi2dc->vc = 0; /* Virtual ID 0 by default */
>>>>> +   csi2dc->clk_gated = false; /* Free running clock by default */
>>>>> +
>>>>> +   return 0;
>>>>> +}
>>>>> +
>>>>> +static int csi2dc_async_bound(struct v4l2_async_notifier *notifier,
>>>>> +                         struct v4l2_subdev *subdev,
>>>>> +                         struct v4l2_async_subdev *asd)
>>>>> +{
>>>>> +   struct csi2dc_device *csi2dc = container_of(notifier->v4l2_dev,
>>>>> +                                   struct csi2dc_device, v4l2_dev);
>>>>> +   int pad;
>>>>> +
>>>>> +   csi2dc->input_sd = subdev;
>>>>> +
>>>>> +   pad = media_entity_get_fwnode_pad(&subdev->entity,
>>>>> +                                     asd->match.fwnode,
>>>>> +                                     MEDIA_PAD_FL_SOURCE);
>>>>> +   if (pad < 0) {
>>>>> +           dev_err(csi2dc->dev, "Failed to find pad for %s\n",
>>>>> +                   subdev->name);
>>>>> +           return pad;
>>>>> +   }
>>>>> +
>>>>> +   csi2dc->remote_pad = pad;
>>>>> +
>>>>> +   csi2dc_get_mbus_config(csi2dc);
>>>>
>>>> The closer to s_stream you call get_mbus_config, the less the chances
>>>> of receiving a stale configuration, if this can happen.
>>>>
>>>>> +
>>>>> +   return 0;
>>>>> +}
>>>>> +
>>>>> +static int csi2dc_async_complete(struct v4l2_async_notifier *notifier)
>>>>> +{
>>>>> +   struct csi2dc_device *csi2dc =
>>>>> +           container_of(notifier->v4l2_dev, struct csi2dc_device,
>>>>> +                        v4l2_dev);
>>>>> +   int ret;
>>>>> +
>>>>> +   ret = csi2dc_formats_init(csi2dc);
>>>>> +   if (ret)
>>>>> +           return ret;
>>>>> +
>>>>> +   ret = v4l2_device_register_subdev_nodes(&csi2dc->v4l2_dev);
>>>>> +   if (ret < 0) {
>>>>> +           v4l2_err(&csi2dc->v4l2_dev,
>>>>> +                    "failed to register subdev nodes\n");
>>>>> +           return ret;
>>>>> +   }
>>>>> +
>>>>> +   csi2dc->completed = true;
>>>>> +
>>>>> +   csi2dc_writel(csi2dc, CSI2DC_GCFG,
>>>>> +                 (SAMA7G5_HLC & CSI2DC_GCFG_HLC_MASK) |
>>>>> +                 (csi2dc->clk_gated ? 0 : CSI2DC_GCFG_MIPIFRN));
>>>>> +
>>>>> +   csi2dc_writel(csi2dc, CSI2DC_VPCOL,
>>>>> +                 CSI2DC_VPCOL_COL(0xFFF) & CSI2DC_VPCOL_COL_MASK);
>>>>> +   csi2dc_writel(csi2dc, CSI2DC_VPROW,
>>>>> +                 CSI2DC_VPROW_ROW(0xFFF) & CSI2DC_VPROW_ROW_MASK);
>>>>> +
>>>>> +   /* once we are completed, we can register ourselves in the pipeline */
>>>>> +   schedule_work(&csi2dc->workq);
>>>>> +
>>>>> +   return ret;
>>>>> +}
>>>>> +
>>>>> +static const struct v4l2_async_notifier_operations csi2dc_async_ops = {
>>>>> +   .bound = csi2dc_async_bound,
>>>>> +   .complete = csi2dc_async_complete,
>>>>> +};
>>>>> +
>>>>> +static void csi2dc_cleanup_notifier(struct csi2dc_device *csi2dc)
>>>>> +{
>>>>> +   v4l2_async_notifier_unregister(&csi2dc->notifier);
>>>>> +   v4l2_async_notifier_cleanup(&csi2dc->notifier);
>>>>> +}
>>>>> +
>>>>> +static int csi2dc_prepare_notifier(struct csi2dc_device *csi2dc,
>>>>> +                              struct device_node *input_parent)
>>>>> +{
>>>>> +   int ret;
>>>>> +
>>>>> +   v4l2_async_notifier_init(&csi2dc->notifier);
>>>>> +
>>>>> +   csi2dc->asd = kzalloc(sizeof(*csi2dc->asd), GFP_KERNEL);
>>>>> +   if (!csi2dc->asd)
>>>>> +           return -ENOMEM;
>>>>> +
>>>>> +   csi2dc->asd->match_type = V4L2_ASYNC_MATCH_FWNODE;
>>>>> +   csi2dc->asd->match.fwnode = of_fwnode_handle(input_parent);
>>>>
>>>> If you use v4l2_async_notifier_add_fwnode_subdev() the framework does
>>>> this for you.
>>>>
>>>>> +
>>>>> +   ret = v4l2_async_notifier_add_subdev(&csi2dc->notifier, csi2dc->asd);
>>>>> +   if (ret) {
>>>>> +           dev_err(csi2dc->dev, "failed to add async notifier.\n");
>>>>> +           v4l2_async_notifier_cleanup(&csi2dc->notifier);
>>>>> +           goto csi2dc_prepare_notifier_err;
>>>>> +   }
>>>>> +
>>>>> +   csi2dc->notifier.ops = &csi2dc_async_ops;
>>>>> +
>>>>> +   ret = v4l2_async_notifier_register(&csi2dc->v4l2_dev,
>>>>> +                                      &csi2dc->notifier);
>>>>> +
>>>>> +   if (ret) {
>>>>> +           dev_err(csi2dc->dev, "fail to register async notifier.\n");
>>>>
>>>> Shouldn't you cleanup the notifier if registration fails ?
>>>>
>>>>> +           goto csi2dc_prepare_notifier_err;
>>>>> +   }
>>>>> +
>>>>> +csi2dc_prepare_notifier_err:
>>>>> +   of_node_put(input_parent);
>>>>> +
>>>>> +   return ret;
>>>>> +}
>>>>> +
>>>>> +static int csi2dc_of_parse(struct csi2dc_device *csi2dc,
>>>>> +                      struct device_node *of_node)
>>>>> +{
>>>>> +   struct device_node *input_node, *sink_node, *input_parent;
>>>>> +   struct v4l2_fwnode_endpoint input_endpoint = { 0 },
>>>>> +                               sink_endpoint = { 0 };
>>>>> +   int ret;
>>>>> +
>>>>> +   input_node = of_graph_get_next_endpoint(of_node, NULL);
>>>>> +
>>>>> +   if (!input_node) {
>>>>> +           dev_err(csi2dc->dev,
>>>>> +                   "missing port node at %s, input node is mandatory.\n",
>>>>
>>>> Please use %pOF to print the node name
>>>> Also, input_node should be put in the error path
>>>>
>>>>> +                   of_node->full_name);
>>>>> +           return -EINVAL;
>>>>> +   }
>>>>> +
>>>>> +   ret = v4l2_fwnode_endpoint_parse(of_fwnode_handle(input_node),
>>>>> +                                    &input_endpoint);
>>>>
>>>> Please set input_endpoint.bus_type if you know what kind of bus you're
>>>> dealing with (not having the bindings of the IDI transmitter I'm not
>>>> sure. Is this V4L2_MBUS_CSI2_DPHY ?)
>>>>
>>>>> +
>>>>> +   if (ret) {
>>>>> +           dev_err(csi2dc->dev, "endpoint not defined at %s\n",
>>>>> +                   of_node->full_name);
>>>>> +           return ret;
>>>>> +   }
>>>>> +
>>>>> +   input_parent = of_graph_get_remote_port_parent(input_node);
>>>>> +   if (!input_parent) {
>>>>
>>>> Missing of_node_put(input_node)
>>>>
>>>>> +           dev_err(csi2dc->dev,
>>>>> +                   "could not get input node's parent node.\n");
>>>>> +           return -EINVAL;
>>>>> +   }
>>>>> +
>>>>> +   sink_node = of_graph_get_next_endpoint(of_node, input_node);
>>>>> +
>>>>> +   if (sink_node)
>>>>> +           ret = v4l2_fwnode_endpoint_parse(of_fwnode_handle(sink_node),
>>>>> +                                            &sink_endpoint);
>>>>
>>>> Same, set sink_endpoint.bus_type if you know it's MBUS_PARALLEL
>>>>
>>>>> +
>>>>> +   if (!sink_node || ret) {
>>>>
>>>> If parsing fail you don't return an error but continue registering the
>>>> notifier and potentially end up registering the async subdev for this
>>>> entity even if the endpoint parsing failed.
>>>>
>>>>> +           dev_info(csi2dc->dev,
>>>>> +                    "missing sink node at %s, data pipe available only.\n",
>>>>> +                    of_node->full_name);
>>>>> +   } else {
>>>>> +           csi2dc->video_pipe = true;
>>>>
>>>> video_pipe is unused it seems
>>>>
>>>>> +
>>>>> +           dev_dbg(csi2dc->dev, "block %s %d.%d->%d.%d video pipeline\n",
>>>>> +                   of_node->full_name, input_endpoint.base.port,
>>>>> +                   input_endpoint.base.id, sink_endpoint.base.port,
>>>>> +                   sink_endpoint.base.id);
>>>>> +   }
>>>>> +
>>>>> +   of_node_put(sink_node);
>>>>> +   of_node_put(input_node);
>>>>> +
>>>>> +   /* prepare async notifier for subdevice completion */
>>>>> +   return csi2dc_prepare_notifier(csi2dc, input_parent);
>>>>> +}
>>>>> +
>>>>> +static void csi2dc_workq_handler(struct work_struct *workq)
>>>>> +{
>>>>> +   struct csi2dc_device *csi2dc = container_of(workq,
>>>>> +                                   struct csi2dc_device, workq);
>>>>> +   int ret;
>>>>> +
>>>>> +   if (v4l2_async_register_subdev(&csi2dc->csi2dc_sd))
>>>>> +           dev_dbg(csi2dc->dev, "failed to register the subdevice\n");
>>>>
>>>> That's peculiar, why do you have to schedule this to a workqueue
>>>> instead of doing this in the complete() callback ?
>>>>
>>>>> +
>>>>> +   ret = csi2dc_power(csi2dc, true);
>>>>> +   if (ret < 0)
>>>>> +           v4l2_err(&csi2dc->v4l2_dev, "failed to power on\n");
>>>>
>>>> Should the device be powered on at s_stream time ? Possibly with a
>>>> pm_runtime_get_sync() call ? I see you register pm_runtime operations,
>>>> but never call get_sync() or _put().
>>>>
>>>> What if CONFIG_PM not selected ? Should this driver select it ? Do you
>>>> have use cases where that's not possible ?
>>>>
>>>>> +}
>>>>> +
>>>>> +static int csi2dc_probe(struct platform_device *pdev)
>>>>> +{
>>>>> +   struct device *dev = &pdev->dev;
>>>>> +   struct csi2dc_device *csi2dc;
>>>>> +   struct resource *res = NULL;
>>>>> +   int ret = 0;
>>>>> +
>>>>> +   csi2dc = devm_kzalloc(dev, sizeof(*csi2dc), GFP_KERNEL);
>>>>> +   if (!csi2dc)
>>>>> +           return -ENOMEM;
>>>>> +
>>>>> +   csi2dc->dev = dev;
>>>>> +
>>>>> +   res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>>>>> +   if (!res)
>>>>> +           return -EINVAL;
>>>>
>>>> devm_ioremap_resource() checks for the validity of 'res' so you can
>>>> drop the previous two lines
>>>>
>>>>> +
>>>>> +   csi2dc->base = devm_ioremap_resource(dev, res);
>>>>> +
>>>>
>>>> Is the empy line intentional, sometimes you have one, sometimes you
>>>> don't ?
>>>>
>>>>> +   if (IS_ERR(csi2dc->base)) {
>>>>> +           dev_err(dev, "base address not set\n");
>>>>
>>>>
>>>>> +           return PTR_ERR(csi2dc->base);
>>>>> +   }
>>>>> +
>>>>> +   csi2dc->pclk = devm_clk_get(dev, "pclk");
>>>>> +   if (IS_ERR(csi2dc->pclk)) {
>>>>> +           ret = PTR_ERR(csi2dc->pclk);
>>>>> +           dev_err(dev, "failed to get pclk: %d\n", ret);
>>>>> +           return ret;
>>>>
>>>> Just return PTR_ERR instead of assigning to ret
>>>>
>>>>> +   }
>>>>> +
>>>>> +   ret = clk_prepare_enable(csi2dc->pclk);
>>>>> +   if (ret) {
>>>>> +           dev_err(dev, "failed to enable pclk: %d\n", ret);
>>>>> +           return ret;
>>>>> +   }
>>>>
>>>> Has this clock to be enabled here or can it be done in the
>>>> pm_runtime callback ?
>>>>
>>>>> +
>>>>> +   csi2dc->scck = devm_clk_get(dev, "scck");
>>>>> +   if (IS_ERR(csi2dc->scck)) {
>>>>> +           ret = PTR_ERR(csi2dc->scck);
>>>>> +           dev_err(dev, "failed to get scck: %d\n", ret);
>>>>> +           goto csi2dc_clk_fail;
>>>>> +   }
>>>>> +
>>>>> +   ret = v4l2_device_register(dev, &csi2dc->v4l2_dev);
>>>>> +   if (ret) {
>>>>> +           dev_err(dev, "unable to register v4l2 device.\n");
>>>>> +           goto csi2dc_clk_fail;
>>>>> +   }
>>>>> +
>>>>> +   v4l2_subdev_init(&csi2dc->csi2dc_sd, &csi2dc_subdev_ops);
>>>>> +
>>>>> +   csi2dc->csi2dc_sd.owner = THIS_MODULE;
>>>>> +   csi2dc->csi2dc_sd.dev = dev;
>>>>> +   snprintf(csi2dc->csi2dc_sd.name, sizeof(csi2dc->csi2dc_sd.name),
>>>>> +            "CSI2DC.0");
>>>>> +
>>>>> +   csi2dc->csi2dc_sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
>>>>> +   csi2dc->csi2dc_sd.entity.function = MEDIA_ENT_F_VID_IF_BRIDGE;
>>>>> +   csi2dc->pads[CSI2DC_PAD_SINK].flags = MEDIA_PAD_FL_SINK;
>>>>> +   csi2dc->pads[CSI2DC_PAD_SOURCE].flags = MEDIA_PAD_FL_SOURCE;
>>>>
>>>> Isn't the source pad presence conditional to the presence of
>>>> port@1 ?
>>>>
>>>>> +
>>>>> +   ret = media_entity_pads_init(&csi2dc->csi2dc_sd.entity, CSI2DC_PADS_NUM,
>>>>> +                                csi2dc->pads);
>>>>> +   if (ret < 0) {
>>>>> +           dev_err(dev, "media entity init failed\n");
>>>>> +           goto csi2dc_probe_entity_err;
>>>>> +   }
>>>>> +
>>>>> +   v4l2_set_subdevdata(&csi2dc->csi2dc_sd, pdev);
>>>>> +
>>>>> +   platform_set_drvdata(pdev, &csi2dc->csi2dc_sd);
>>>>> +
>>>>> +   INIT_WORK(&csi2dc->workq, csi2dc_workq_handler);
>>>>> +
>>>>> +   ret = csi2dc_of_parse(csi2dc, dev->of_node);
>>>>> +   if (ret)
>>>>> +           goto csi2dc_probe_entity_err;
>>>>> +
>>>>> +   dev_info(dev, "Microchip CSI2DC version %x\n",
>>>>> +            csi2dc_readl(csi2dc, CSI2DC_VERSION));
>>>>> +
>>>>> +   pm_runtime_set_active(dev);
>>>>> +   pm_runtime_enable(dev);
>>>>> +   pm_request_idle(dev);
>>>>> +
>>>>> +   return 0;
>>>>> +
>>>>> +csi2dc_probe_entity_err:
>>>>> +   media_entity_cleanup(&csi2dc->csi2dc_sd.entity);
>>>>> +   v4l2_device_unregister(&csi2dc->v4l2_dev);
>>>>> +csi2dc_clk_fail:
>>>>> +   clk_disable_unprepare(csi2dc->pclk);
>>>>> +   return ret;
>>>>> +}
>>>>> +
>>>>> +static int csi2dc_remove(struct platform_device *pdev)
>>>>> +{
>>>>> +   struct v4l2_subdev *csi2dc_sd = platform_get_drvdata(pdev);
>>>>> +   struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
>>>>> +
>>>>> +   pm_runtime_disable(&pdev->dev);
>>>>> +
>>>>> +   v4l2_async_unregister_subdev(&csi2dc->csi2dc_sd);
>>>>> +   csi2dc_cleanup_notifier(csi2dc);
>>>>> +   media_entity_cleanup(&csi2dc->csi2dc_sd.entity);
>>>>> +   v4l2_device_unregister(&csi2dc->v4l2_dev);
>>>>> +   clk_disable_unprepare(csi2dc->pclk);
>>>>> +
>>>>> +   return 0;
>>>>> +}
>>>>> +
>>>>> +static int __maybe_unused csi2dc_runtime_suspend(struct device *dev)
>>>>> +{
>>>>> +   struct csi2dc_device *csi2dc = dev_get_drvdata(dev);
>>>>> +
>>>>> +   return csi2dc_power(csi2dc, false);
>>>>> +}
>>>>> +
>>>>> +static int __maybe_unused csi2dc_runtime_resume(struct device *dev)
>>>>> +{
>>>>> +   struct csi2dc_device *csi2dc = dev_get_drvdata(dev);
>>>>> +
>>>>> +   return csi2dc_power(csi2dc, true);
>>>>> +}
>>>>> +
>>>>> +static const struct dev_pm_ops csi2dc_dev_pm_ops = {
>>>>> +   SET_RUNTIME_PM_OPS(csi2dc_runtime_suspend, csi2dc_runtime_resume, NULL)
>>>>> +};
>>>>> +
>>>>> +static const struct of_device_id csi2dc_of_match[] = {
>>>>> +   { .compatible = "microchip,sama7g5-csi2dc" },
>>>>> +   { }
>>>>> +};
>>>>> +
>>>>> +MODULE_DEVICE_TABLE(of, csi2dc_of_match);
>>>>> +
>>>>> +static struct platform_driver csi2dc_driver = {
>>>>> +   .probe  = csi2dc_probe,
>>>>> +   .remove = csi2dc_remove,
>>>>> +   .driver = {
>>>>> +           .name           = "microchip-csi2dc",
>>>>> +           .pm             = &csi2dc_dev_pm_ops,
>>>>> +           .of_match_table = of_match_ptr(csi2dc_of_match),
>>>>> +   },
>>>>> +};
>>>>> +
>>>>> +module_platform_driver(csi2dc_driver);
>>>>> +
>>>>> +MODULE_AUTHOR("Eugen Hristev <eugen.hristev@microchip.com>");
>>>>> +MODULE_DESCRIPTION("Microchip CSI2 Demux Controller driver");
>>>>> +MODULE_LICENSE("GPL v2");
>>>>> +MODULE_SUPPORTED_DEVICE("video");
>>>>
>>>> For my education, what's MODULE_SUPPORTED_DEVICE for ?
>>>
>>> It's "not yet implemented" since 2005, I think it can be dropped :-)
>>>
>>> --
>>> Regards,
>>>
>>> Laurent Pinchart
>>>
>>

Re: [PATCH v5 2/3] media: atmel: introduce microchip csi2dc driver

[Jacopo Mondi]

Hi Eugen,

On Wed, Nov 18, 2020 at 09:48:19AM +0000, Eugen.Hristev@microchip.com wrote:
> On 18.11.2020 11:11, Jacopo Mondi wrote:
> > Hello Eugen,
> >

[snip]

> >> Hello,
> >>
> >> First of all thank you for the review and explanations.
> >>
> >> I am still confused about how does the userspace know which elements are
> >> in the pipeline and how to connect them ?
> >
> > Using the media-controller uAPI to inspect, explore and configure the
> > media graph (it's mostly about enabling and disabling media links),
> > and using the v4l2 subdev uAPI to configure formats, sizes and such on
> > each subdevice device node associated with a media entity. Finally,
> > using the v4l2 uAPI to stream from the top-level driver that expose a
> > video device node.
>
> Okay but which application in userspace uses this userAPI ?

media-ctl which is part of v4l2-utils.

existing applications or frameworks like gstreamer have no notion of
the platform they run on, they can't configure it, they only
understand '/dev/video0'

> So I could use it to test my pipeline.
>

The first step is to use media-ctl to manually setup the pipeline and
test. Once it's setup you can usually keep using the legacy
applications that only stream from /dev/video0.

Of course manually setting up the pipeline using a script does not
scale, that's what the 'libcamera pipeline handler' does in facts.
It implements the same logic that you would manually apply with
media-ctl

> >
> > It's really (conceptually) not different than doing the same using
> > media-ctl and v4l2-ctl.
> >
> >> And if this is the case, what is the purpose of the endpoints in the DT ?
> >>
> >
> > DTS describe the hardware. Usually a driver parses the firmware graph
> > to create and model the media graph and the available connections
> > between media entities but there's no requirement to have a 1-to-1
> > match (as far I'm aware).
>
> So the top level v4l2 driver should parse the whole graph ?
>

Userspace should :)

> >
> > Media links on a media graph then need to be enabled opportunely
> > depending on the desired use case, the platform topology etc
> >
> >> At this moment, I just use the /dev/video0, because the top v4l2 driver
> >> configures the subdevice, and this subdevice configures it's own
> >> subdevice and so on, until the sensor itself.
> >>
> >> My top v4l2 driver will not 'complete' unless a subdevice registers
> >> itself , and if this subdevice does not provide any information
> >> regarding its formats, the probe of the top v4l2 driver will fail,
> >> because it will not find compatibility between it's supported input
> >> formats and what the subdevice provides.
> >
> > ouch, I see.. Which driver is that ?
>
> The atmel image sensor controller driver.
> All sensor drivers that we use (for example : ov5640, ov7740, ov7670)
> register as subdevices, and the atmel-isc will 'complete' when the
> sensor is probed and registered.

That's ok, the complete callback is called when all the async devices
registered in a notifier are matched.

> To have the csi2dc module compatible with what we have on atmel-isc,
> it's natural to have the csi2dc register itself as a subdevice such that
> the atmel-isc can 'complete'.

the csi2d registering as subdev is all good (apart from the issue of
having 2 v4l2_device, but as you've see there's a solution for that
and it's called sub-notifiers).

The 'issue' here is that your top driver wants to match formats to initialize
its supported format list (in isc_formats_init() from what I can see).

An MC driver should not care about that. Each piece of the pipeline
has to be considered in isolation, and the format matching happens at
link_validate() time for links between subdevices and usually at
s_stream(1) time between sub-devices and video devices.

In example, format enumeration on the video device registered by the
top v4l2 driver is conditional to the presence of the mbus_code field
as you can read in:
https://www.kernel.org/doc/html/latest/userspace-api/media/v4l/vidioc-enum-fmt.html?highlight=enum_fmt#c.V4L.VIDIOC_ENUM_FMT

And it should be possible by setting mbus_code = 0 to get a list of
all formats supported -by the hardware- not limited to the current use
case.

Userspace knows the platform and if asked for 640x480[YUV420] will go
and set the right format on each piece of the pipeline, after having
enabled the relevant links, using the right media bus codes and sizes

Totally random example:

        [video0] s_fmt(640x480, PIXFMT_YUV422)
         (pad 0)
           |
           v
         (pad 1) sudev_s_fmt(1, 640x480, MBUS_YUYV8_1X16)
        [csi2dc]       --- your subdev can crop ---
         (pad 0) sudev_s_fmt(0, 648x496, MBUS_YUYV8_1X16)
           |
           V
         (pad 0) subdev_s_fmt(0, 648x496, MBUS_YUYV_1X16)
        [ov5640]

If your top v4l2 driver can produce RGB from a YUV stream it's
perfectly legit then to s_fmt(video0, 640x480, PIXFMT_RGB565) and
subdev_s_fmt(csi2dc, 1, 640x480, MBUS_YUYV8_1X16).

As you can see it all depends on what your hardware can do.

>
>
> >
> > If that's an MC driver, and that seems the case, it should not bother
> > validating the subdevice formats, but only care about listing what its
> > capabilities are.
>
> if this atmel-isc does not offer format capabilities for the userspace
> via the /dev/video0, then all applications that we use (gstreamer
> v4l2src, ffmpeg ) fail.
> What can we use then, if we cannot use these applications ?
>

I think if you setup the pipeline with media-ctl correctly (ie you
don't get any -EPIPE at s_stream) you should be able to keep using
legacy apps, but it very much depends on how they are implemented.

Usually setting up the pipeline using media-ctl and streaming using
v4l2-ctl or yavta is the first validation test.

> >
> >>
> >> So what to do in this case ? Libcamera will configure this whole
> >> pipeline for me , if the drivers just probe ( and start/stop streaming
> >> by selecting the respective registers) ? or how to do this whole
> >> pipeline configuration ?
> >>
> >
> > Well, libcamera offers a framework to enable specialized code (called
> > "pipeline handler") to operate under an high-level API towards application
> > and implement image tuning algorithms on top of that common API.
> >
> > The code to configure the pipeline is device specific (unless your
> > pipeline is very simple). So it's not that libcamera just magically
> > knows how to operate on every platforms it runs on, it needs platform
> > specific code to do so. What you get in exchange is an high level API
> > to offer to application developers, a framework to implement 3A and
> > tuning algorithms, integration with a growing set of other userspace
> > frameworks (android, gstreamer, pipewire and a legacy v4l2-compat
> > layer)
>
> I tried a buildroot with libcamera and gstreamer libcamerasrc , to see
> how it goes. Libcamera does not recognize the /dev/video0 device that we
> have. The v4l2 compatibility layer should not perform exactly this ?

There's no pipeline handler for your platform (unless you have
developed one)

>
> # gst-launch-1.0 libcamerasrc ! fakesink
> Setting pipeline to PAUSED ...
> [0:00:28.448687200] [216]  WARN IPAManager ipa_manager.cpp:147 No IPA
> found in '/usr/lib/libcamera'
> [0:00:28.448890800] [216]  INFO Camera camera_manager.cpp:287 libcamera
> v0.0.0+54328-2020.11-rc2-dirty (2020-11-17T20:58:37+02:00)
> ERROR: from element
> /GstPipeline:pipeline0/GstLibcameraSrc:libcamerasrc0: Could not find any
> supported camera on this system.
            ^
And this is the expected outcome :)

As said, it's not that libcamera magically knows how to deal with all
devices it is run on. We would not need libcamera at all if that was
the case, any application would be self-configurable and that's it :)

Re: [PATCH v5 2/3] media: atmel: introduce microchip csi2dc driver

[Eugen.Hristev]

On 18.11.2020 13:38, Jacopo Mondi wrote:
> Hi Eugen,
> 
> On Wed, Nov 18, 2020 at 09:48:19AM +0000, Eugen.Hristev@microchip.com wrote:
>> On 18.11.2020 11:11, Jacopo Mondi wrote:
>>> Hello Eugen,
>>>
> 
> [snip]
> 
>>>> Hello,
>>>>
>>>> First of all thank you for the review and explanations.
>>>>
>>>> I am still confused about how does the userspace know which elements are
>>>> in the pipeline and how to connect them ?
>>>
>>> Using the media-controller uAPI to inspect, explore and configure the
>>> media graph (it's mostly about enabling and disabling media links),
>>> and using the v4l2 subdev uAPI to configure formats, sizes and such on
>>> each subdevice device node associated with a media entity. Finally,
>>> using the v4l2 uAPI to stream from the top-level driver that expose a
>>> video device node.
>>
>> Okay but which application in userspace uses this userAPI ?
> 
> media-ctl which is part of v4l2-utils.
> 
> existing applications or frameworks like gstreamer have no notion of
> the platform they run on, they can't configure it, they only
> understand '/dev/video0'
> 
>> So I could use it to test my pipeline.
>>
> 
> The first step is to use media-ctl to manually setup the pipeline and
> test. Once it's setup you can usually keep using the legacy
> applications that only stream from /dev/video0.
> 
> Of course manually setting up the pipeline using a script does not
> scale, that's what the 'libcamera pipeline handler' does in facts.
> It implements the same logic that you would manually apply with
> media-ctl
> 
>>>
>>> It's really (conceptually) not different than doing the same using
>>> media-ctl and v4l2-ctl.
>>>
>>>> And if this is the case, what is the purpose of the endpoints in the DT ?
>>>>
>>>
>>> DTS describe the hardware. Usually a driver parses the firmware graph
>>> to create and model the media graph and the available connections
>>> between media entities but there's no requirement to have a 1-to-1
>>> match (as far I'm aware).
>>
>> So the top level v4l2 driver should parse the whole graph ?
>>
> 
> Userspace should :)
> 
>>>
>>> Media links on a media graph then need to be enabled opportunely
>>> depending on the desired use case, the platform topology etc
>>>
>>>> At this moment, I just use the /dev/video0, because the top v4l2 driver
>>>> configures the subdevice, and this subdevice configures it's own
>>>> subdevice and so on, until the sensor itself.
>>>>
>>>> My top v4l2 driver will not 'complete' unless a subdevice registers
>>>> itself , and if this subdevice does not provide any information
>>>> regarding its formats, the probe of the top v4l2 driver will fail,
>>>> because it will not find compatibility between it's supported input
>>>> formats and what the subdevice provides.
>>>
>>> ouch, I see.. Which driver is that ?
>>
>> The atmel image sensor controller driver.
>> All sensor drivers that we use (for example : ov5640, ov7740, ov7670)
>> register as subdevices, and the atmel-isc will 'complete' when the
>> sensor is probed and registered.
> 
> That's ok, the complete callback is called when all the async devices
> registered in a notifier are matched.
> 
>> To have the csi2dc module compatible with what we have on atmel-isc,
>> it's natural to have the csi2dc register itself as a subdevice such that
>> the atmel-isc can 'complete'.
> 
> the csi2d registering as subdev is all good (apart from the issue of
> having 2 v4l2_device, but as you've see there's a solution for that
> and it's called sub-notifiers).
> 
> The 'issue' here is that your top driver wants to match formats to initialize
> its supported format list (in isc_formats_init() from what I can see).
> 
> An MC driver should not care about that. Each piece of the pipeline
> has to be considered in isolation, and the format matching happens at
> link_validate() time for links between subdevices and usually at
> s_stream(1) time between sub-devices and video devices.
> 
> In example, format enumeration on the video device registered by the
> top v4l2 driver is conditional to the presence of the mbus_code field
> as you can read in:
> https://www.kernel.org/doc/html/latest/userspace-api/media/v4l/vidioc-enum-fmt.html?highlight=enum_fmt#c.V4L.VIDIOC_ENUM_FMT
> 
> And it should be possible by setting mbus_code = 0 to get a list of
> all formats supported -by the hardware- not limited to the current use
> case.
> 
> Userspace knows the platform and if asked for 640x480[YUV420] will go
> and set the right format on each piece of the pipeline, after having
> enabled the relevant links, using the right media bus codes and sizes
> 
> Totally random example:
> 
>          [video0] s_fmt(640x480, PIXFMT_YUV422)
>           (pad 0)
>             |
>             v
>           (pad 1) sudev_s_fmt(1, 640x480, MBUS_YUYV8_1X16)
>          [csi2dc]       --- your subdev can crop ---
>           (pad 0) sudev_s_fmt(0, 648x496, MBUS_YUYV8_1X16)
>             |
>             V
>           (pad 0) subdev_s_fmt(0, 648x496, MBUS_YUYV_1X16)
>          [ov5640]
> 
> If your top v4l2 driver can produce RGB from a YUV stream it's
> perfectly legit then to s_fmt(video0, 640x480, PIXFMT_RGB565) and
> subdev_s_fmt(csi2dc, 1, 640x480, MBUS_YUYV8_1X16).
> 
> As you can see it all depends on what your hardware can do.
> 

Hi again,

Thank you very much for the explanations. It is different from what I 
had in mind (and how we use the subsystem right now in our drivers here 
). I will take some time to understand all this, and hopefully I can 
come with better drivers, better pipeline handling and libcamera 
platform support.

I may have questions during the development, but I think I have enough 
information to get started.

thanks again !

Eugen
>>
>>
>>>
>>> If that's an MC driver, and that seems the case, it should not bother
>>> validating the subdevice formats, but only care about listing what its
>>> capabilities are.
>>
>> if this atmel-isc does not offer format capabilities for the userspace
>> via the /dev/video0, then all applications that we use (gstreamer
>> v4l2src, ffmpeg ) fail.
>> What can we use then, if we cannot use these applications ?
>>
> 
> I think if you setup the pipeline with media-ctl correctly (ie you
> don't get any -EPIPE at s_stream) you should be able to keep using
> legacy apps, but it very much depends on how they are implemented.
> 
> Usually setting up the pipeline using media-ctl and streaming using
> v4l2-ctl or yavta is the first validation test.
> 
>>>
>>>>
>>>> So what to do in this case ? Libcamera will configure this whole
>>>> pipeline for me , if the drivers just probe ( and start/stop streaming
>>>> by selecting the respective registers) ? or how to do this whole
>>>> pipeline configuration ?
>>>>
>>>
>>> Well, libcamera offers a framework to enable specialized code (called
>>> "pipeline handler") to operate under an high-level API towards application
>>> and implement image tuning algorithms on top of that common API.
>>>
>>> The code to configure the pipeline is device specific (unless your
>>> pipeline is very simple). So it's not that libcamera just magically
>>> knows how to operate on every platforms it runs on, it needs platform
>>> specific code to do so. What you get in exchange is an high level API
>>> to offer to application developers, a framework to implement 3A and
>>> tuning algorithms, integration with a growing set of other userspace
>>> frameworks (android, gstreamer, pipewire and a legacy v4l2-compat
>>> layer)
>>
>> I tried a buildroot with libcamera and gstreamer libcamerasrc , to see
>> how it goes. Libcamera does not recognize the /dev/video0 device that we
>> have. The v4l2 compatibility layer should not perform exactly this ?
> 
> There's no pipeline handler for your platform (unless you have
> developed one)
> 
>>
>> # gst-launch-1.0 libcamerasrc ! fakesink
>> Setting pipeline to PAUSED ...
>> [0:00:28.448687200] [216]  WARN IPAManager ipa_manager.cpp:147 No IPA
>> found in '/usr/lib/libcamera'
>> [0:00:28.448890800] [216]  INFO Camera camera_manager.cpp:287 libcamera
>> v0.0.0+54328-2020.11-rc2-dirty (2020-11-17T20:58:37+02:00)
>> ERROR: from element
>> /GstPipeline:pipeline0/GstLibcameraSrc:libcamerasrc0: Could not find any
>> supported camera on this system.
>              ^
> And this is the expected outcome :)
> 
> As said, it's not that libcamera magically knows how to deal with all
> devices it is run on. We would not need libcamera at all if that was
> the case, any application would be self-configurable and that's it :)
> 

[PATCH v5 3/3] MAINTAINERS: add microchip csi2dc

[Eugen Hristev]

Add Microchip CSI2DC driver in the list.

Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
---
 MAINTAINERS | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 2ec6fda103f8..3392a5803743 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11472,6 +11472,13 @@ L:	alsa-devel@alsa-project.org (moderated for non-subscribers)
 S:	Supported
 F:	sound/soc/atmel
 
+MICROCHIP CSI2DC DRIVER
+M:	Eugen Hristev <eugen.hristev@microchip.com>
+L:	linux-media@vger.kernel.org
+S:	Supported
+F:	Documentation/devicetree/bindings/media/microchip,csi2dc.yaml
+F:	drivers/media/platform/atmel/microchip-csi2dc.c
+
 MICROCHIP ECC DRIVER
 M:	Tudor Ambarus <tudor.ambarus@microchip.com>
 L:	linux-crypto@vger.kernel.org
-- 
2.25.1

Re: [PATCH v5 1/3] dt-bindings: media: atmel: csi2dc: add bindings for microchip csi2dc

[Jacopo Mondi]

Hello Eugen,

On Thu, Nov 12, 2020 at 03:34:35PM +0200, Eugen Hristev wrote:
> Add bindings documentation for Microchip CSI2 Demultiplexer controller.
>
> CSI2DC is a demultiplexer from Synopsys IDI interface specification to
> parallel interface connection or direct memory access.
>
> Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
> ---
> Changes in v5:
> - modified bindings as per Rob Herring review
>
> Changes in v4:
> - Removed property for inter-line-delay and for clock continuous/non-continuous
> - Removed virtual channel by reg for second endpoint
>
> Changes in v3:
> - Removed some text from description, as it was explained in the schema
> - fixed other things as per Rob's review
> - moved some text inside the schema, like the clock description
>
> Changes in v2:
> - fixed warnings reported by dt_binding_check
>
>  .../bindings/media/microchip,csi2dc.yaml      | 119 ++++++++++++++++++
>  1 file changed, 119 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/media/microchip,csi2dc.yaml
>
> diff --git a/Documentation/devicetree/bindings/media/microchip,csi2dc.yaml b/Documentation/devicetree/bindings/media/microchip,csi2dc.yaml
> new file mode 100644
> index 000000000000..e79f0d6ba9db
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/media/microchip,csi2dc.yaml
> @@ -0,0 +1,119 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/media/microchip,csi2dc.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Microchip CSI2 Demux Controller (CSI2DC)
> +
> +maintainers:
> +  - Eugen Hristev <eugen.hristev@microchip.com>
> +
> +description:
> +  CSI2DC - Camera Serial Interface 2 Demux Controller
> +
> +  CSI2DC is a hardware block that receives incoming data from an IDI interface
> +  and filters packets based on their data type and virtual channel identifier,
> +  then converts the byte stream into a cross clock domain to a pixel stream
> +  to a parallel interface that can be read by a sensor controller.
> +
> +  CSI2DC provides two pipes, one video pipe and one data pipe. Video pipe
> +  is connected to a sensor controller and the data pipe is accessible
> +  as a DMA slave port to a DMA controller.
> +
> +  CSI2DC supports a single 'port' node as a source pad with Synopsys 32-bit
> +  IDI interface. The connected endpoint must be a IDI interface compatible
> +  device (like Synopsys CSI2HOST) , that can provide 32-bit IDI interface
> +  connection as sink pad.

Comments on a description from a non-native speaker might be
mis-leading, take the following as suggestions only :)

the here mentioned port node is said to be a 'source' to which an IDI
interface that provides data is connected ? Is this a s/sink/source
mistake or did you mean the first port node has to be connected to a
source (the IDI interface) ?

Also, maybe it's me but 'pad' is a media-controller concept, which
should not be mentioned in bindings (as well as 'source' and 'sink'
but they have a more generic usage)

The first port, to me, is simply an 'IDI input port'

> +  For media entity and endpoints please refer to the bindings defined in
> +  Documentation/devicetree/bindings/media/video-interfaces.txt.

I would drop 'media-entity'. To be honest I would drop this phrase and
mention ../video-interfaces.txt in the ports description. Up to you.

> +  For Synopsys IDI interface please refer to
> +  Documentation/devicetree/bindings/media/snps,dw-csi-plat.txt
> +
> +  CSI2DC supports one 'port' node as sink pad with parallel interface. This is
> +  called video pipe.

I'm confused again, isn't the parallel interface an output ? Why is it
said to be a 'sink pad' ?

Isn't port one simply a 'video output port' ?

Also the association between bindings' 'port' and their representation
as media-controller constructs should in my opinion be avoided.
Bindings are about describing hardware, and they could be used by
non-Linux systems as well (at least, I've been told this multiple
times :)

> +  This port has an 'endpoint' can then be used as a source pad for another
> +  controller (next in pipeline).
> +  Please refer to the bindings defined in
> +  Documentation/devicetree/bindings/media/video-interfaces.txt.
> +
> +  CSI2DC also supports direct access to the data through AHB, via DMA channel,
> +  called data pipe.

Is my understanding correct of this 'direct access' is not represented
in DTS ?

> +  Because of this, the sink 'port' child node (second) is not mandatory.
> +  If the sink 'port' child node is missing, only data pipe is available.

And so the DMA channel and the output video port are mutually
exclusive ? I feel like the DMA port should be described or at least
represented and made exclusive with port1 presence ?

> +
> +properties:
> +  compatible:
> +    const: microchip,sama7g5-csi2dc
> +
> +  reg:
> +    maxItems: 1
> +
> +  clocks:
> +    maxItems: 2
> +
> +  clock-names:
> +    description:
> +      CSI2DC must have two clocks to function correctly. One clock is the
> +      peripheral clock for the inside functionality of the hardware block.
> +      This is named 'pclk'. The second clock must be the cross domain clock,
> +      in which CSI2DC will perform clock crossing. This clock must be fed
> +      by the next controller in pipeline, which usually is a sensor controller.
> +      Normally this clock should be given by this sensor controller who
> +      is also a clock source. This clock is named 'scck', sensor controller clock.
> +    items:
> +      - const: pclk
> +      - const: scck
> +
> +  ports:
> +    type: object
> +    description:
> +      List of ports
> +
> +    properties:
> +      port@0:
> +        type: object
> +        description:
> +          Input port node, single endpoint describing the input pad.
> +      port@1:
> +        type: object
> +        description:
> +          Output port node, single endpoint, describing the output pad.

That's a parallel video output, correct ? Does this port support any
configurable property of the ones defined by video-interfaces.txt ?

Thanks
   j
> +
> +additionalProperties: false
> +
> +required:
> +  - compatible
> +  - reg
> +  - clocks
> +  - clock-names
> +  - ports
> +
> +examples:
> +  - |
> +    csi2dc@e1404000 {
> +        compatible = "microchip,sama7g5-csi2dc";
> +        reg = <0xe1404000 0x500>;
> +        clocks = <&pclk>, <&scck>;
> +        clock-names = "pclk", "scck";
> +
> +        ports {
> +               #address-cells = <1>;
> +               #size-cells = <0>;
> +               port@0 {
> +                       reg = <0>; /* must be 0, first child port */
> +                       csi2dc_in: endpoint { /* input from IDI interface */
> +                               remote-endpoint = <&csi2host_out>;
> +                       };
> +               };
> +
> +               port@1 {
> +                       reg = <1>; /* must be 1, second child port */
> +                       csi2dc_out: endpoint {
> +                               remote-endpoint = <&xisc_in>; /* output to sensor controller */
> +                       };
> +               };
> +        };
> +    };
> +
> +...
> --
> 2.25.1
>

Re: [PATCH v5 1/3] dt-bindings: media: atmel: csi2dc: add bindings for microchip csi2dc

[Jacopo Mondi]

Hi again,

On Thu, Nov 12, 2020 at 03:34:35PM +0200, Eugen Hristev wrote:
> Add bindings documentation for Microchip CSI2 Demultiplexer controller.
>
> CSI2DC is a demultiplexer from Synopsys IDI interface specification to
> parallel interface connection or direct memory access.
>
> Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
> ---
> Changes in v5:
> - modified bindings as per Rob Herring review
>
> Changes in v4:
> - Removed property for inter-line-delay and for clock continuous/non-continuous
> - Removed virtual channel by reg for second endpoint
>
> Changes in v3:
> - Removed some text from description, as it was explained in the schema
> - fixed other things as per Rob's review
> - moved some text inside the schema, like the clock description
>
> Changes in v2:
> - fixed warnings reported by dt_binding_check
>
>  .../bindings/media/microchip,csi2dc.yaml      | 119 ++++++++++++++++++
>  1 file changed, 119 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/media/microchip,csi2dc.yaml
>
> diff --git a/Documentation/devicetree/bindings/media/microchip,csi2dc.yaml b/Documentation/devicetree/bindings/media/microchip,csi2dc.yaml
> new file mode 100644
> index 000000000000..e79f0d6ba9db
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/media/microchip,csi2dc.yaml
> @@ -0,0 +1,119 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/media/microchip,csi2dc.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Microchip CSI2 Demux Controller (CSI2DC)
> +
> +maintainers:
> +  - Eugen Hristev <eugen.hristev@microchip.com>
> +
> +description:
> +  CSI2DC - Camera Serial Interface 2 Demux Controller
> +
> +  CSI2DC is a hardware block that receives incoming data from an IDI interface
> +  and filters packets based on their data type and virtual channel identifier,
> +  then converts the byte stream into a cross clock domain to a pixel stream
> +  to a parallel interface that can be read by a sensor controller.
> +
> +  CSI2DC provides two pipes, one video pipe and one data pipe. Video pipe
> +  is connected to a sensor controller and the data pipe is accessible
> +  as a DMA slave port to a DMA controller.
> +
> +  CSI2DC supports a single 'port' node as a source pad with Synopsys 32-bit
> +  IDI interface. The connected endpoint must be a IDI interface compatible
> +  device (like Synopsys CSI2HOST) , that can provide 32-bit IDI interface
> +  connection as sink pad.
> +  For media entity and endpoints please refer to the bindings defined in
> +  Documentation/devicetree/bindings/media/video-interfaces.txt.
> +  For Synopsys IDI interface please refer to
> +  Documentation/devicetree/bindings/media/snps,dw-csi-plat.txt

Is it me or this file doesn't exists on the most recent media/master
and on v5.10-rc4 ?

> +
> +  CSI2DC supports one 'port' node as sink pad with parallel interface. This is
> +  called video pipe.
> +  This port has an 'endpoint' can then be used as a source pad for another
> +  controller (next in pipeline).
> +  Please refer to the bindings defined in
> +  Documentation/devicetree/bindings/media/video-interfaces.txt.
> +
> +  CSI2DC also supports direct access to the data through AHB, via DMA channel,
> +  called data pipe.
> +  Because of this, the sink 'port' child node (second) is not mandatory.
> +  If the sink 'port' child node is missing, only data pipe is available.
> +
> +properties:
> +  compatible:
> +    const: microchip,sama7g5-csi2dc
> +
> +  reg:
> +    maxItems: 1
> +
> +  clocks:
> +    maxItems: 2
> +
> +  clock-names:
> +    description:
> +      CSI2DC must have two clocks to function correctly. One clock is the
> +      peripheral clock for the inside functionality of the hardware block.
> +      This is named 'pclk'. The second clock must be the cross domain clock,
> +      in which CSI2DC will perform clock crossing. This clock must be fed
> +      by the next controller in pipeline, which usually is a sensor controller.
> +      Normally this clock should be given by this sensor controller who
> +      is also a clock source. This clock is named 'scck', sensor controller clock.
> +    items:
> +      - const: pclk
> +      - const: scck
> +
> +  ports:
> +    type: object
> +    description:
> +      List of ports
> +
> +    properties:
> +      port@0:
> +        type: object
> +        description:
> +          Input port node, single endpoint describing the input pad.
> +      port@1:
> +        type: object
> +        description:
> +          Output port node, single endpoint, describing the output pad.
> +
> +additionalProperties: false
> +
> +required:
> +  - compatible
> +  - reg
> +  - clocks
> +  - clock-names
> +  - ports
> +
> +examples:
> +  - |
> +    csi2dc@e1404000 {
> +        compatible = "microchip,sama7g5-csi2dc";
> +        reg = <0xe1404000 0x500>;
> +        clocks = <&pclk>, <&scck>;
> +        clock-names = "pclk", "scck";
> +
> +        ports {
> +               #address-cells = <1>;
> +               #size-cells = <0>;
> +               port@0 {
> +                       reg = <0>; /* must be 0, first child port */
> +                       csi2dc_in: endpoint { /* input from IDI interface */
> +                               remote-endpoint = <&csi2host_out>;
> +                       };
> +               };
> +
> +               port@1 {
> +                       reg = <1>; /* must be 1, second child port */
> +                       csi2dc_out: endpoint {
> +                               remote-endpoint = <&xisc_in>; /* output to sensor controller */
> +                       };
> +               };
> +        };
> +    };
> +
> +...
> --
> 2.25.1
>

Re: [PATCH v5 1/3] dt-bindings: media: atmel: csi2dc: add bindings for microchip csi2dc

[Eugen.Hristev]

On 17.11.2020 12:37, Jacopo Mondi wrote:
> Hi again,
> 
> On Thu, Nov 12, 2020 at 03:34:35PM +0200, Eugen Hristev wrote:
>> Add bindings documentation for Microchip CSI2 Demultiplexer controller.
>>
>> CSI2DC is a demultiplexer from Synopsys IDI interface specification to
>> parallel interface connection or direct memory access.
>>
>> Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
>> ---
>> Changes in v5:
>> - modified bindings as per Rob Herring review
>>
>> Changes in v4:
>> - Removed property for inter-line-delay and for clock continuous/non-continuous
>> - Removed virtual channel by reg for second endpoint
>>
>> Changes in v3:
>> - Removed some text from description, as it was explained in the schema
>> - fixed other things as per Rob's review
>> - moved some text inside the schema, like the clock description
>>
>> Changes in v2:
>> - fixed warnings reported by dt_binding_check
>>
>>   .../bindings/media/microchip,csi2dc.yaml      | 119 ++++++++++++++++++
>>   1 file changed, 119 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/media/microchip,csi2dc.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/media/microchip,csi2dc.yaml b/Documentation/devicetree/bindings/media/microchip,csi2dc.yaml
>> new file mode 100644
>> index 000000000000..e79f0d6ba9db
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/media/microchip,csi2dc.yaml
>> @@ -0,0 +1,119 @@
>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/media/microchip,csi2dc.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Microchip CSI2 Demux Controller (CSI2DC)
>> +
>> +maintainers:
>> +  - Eugen Hristev <eugen.hristev@microchip.com>
>> +
>> +description:
>> +  CSI2DC - Camera Serial Interface 2 Demux Controller
>> +
>> +  CSI2DC is a hardware block that receives incoming data from an IDI interface
>> +  and filters packets based on their data type and virtual channel identifier,
>> +  then converts the byte stream into a cross clock domain to a pixel stream
>> +  to a parallel interface that can be read by a sensor controller.
>> +
>> +  CSI2DC provides two pipes, one video pipe and one data pipe. Video pipe
>> +  is connected to a sensor controller and the data pipe is accessible
>> +  as a DMA slave port to a DMA controller.
>> +
>> +  CSI2DC supports a single 'port' node as a source pad with Synopsys 32-bit
>> +  IDI interface. The connected endpoint must be a IDI interface compatible
>> +  device (like Synopsys CSI2HOST) , that can provide 32-bit IDI interface
>> +  connection as sink pad.
>> +  For media entity and endpoints please refer to the bindings defined in
>> +  Documentation/devicetree/bindings/media/video-interfaces.txt.
>> +  For Synopsys IDI interface please refer to
>> +  Documentation/devicetree/bindings/media/snps,dw-csi-plat.txt
> 
> Is it me or this file doesn't exists on the most recent media/master
> and on v5.10-rc4 ?

Hi Jacopo,

Thanks for reviewing this patch.
You are right. As I said at some point during the review, actually this 
controller has an input the IDI interface which is not currently in 
kernel. There is a patch series that adds the Synopsys platform driver, 
but nobody worked on it anymore and I use it for testing my driver.
You can see the last version that was sent here:

https://patchwork.linuxtv.org/project/linux-media/patch/1560280855-18085-2-git-send-email-luis.oliveira@synopsys.com/ 


I sent this series to understand how to improve and how to get my driver 
in kernel, but indeed there are holes, especially this input type of bus 
which is not in the subsystem either.

So how would you suggest to move forward ? Remove the reference to the 
synopsys binding and just leave 'IDI interface' which is undocumented ?

Eugen

> 
>> +
>> +  CSI2DC supports one 'port' node as sink pad with parallel interface. This is
>> +  called video pipe.
>> +  This port has an 'endpoint' can then be used as a source pad for another
>> +  controller (next in pipeline).
>> +  Please refer to the bindings defined in
>> +  Documentation/devicetree/bindings/media/video-interfaces.txt.
>> +
>> +  CSI2DC also supports direct access to the data through AHB, via DMA channel,
>> +  called data pipe.
>> +  Because of this, the sink 'port' child node (second) is not mandatory.
>> +  If the sink 'port' child node is missing, only data pipe is available.
>> +
>> +properties:
>> +  compatible:
>> +    const: microchip,sama7g5-csi2dc
>> +
>> +  reg:
>> +    maxItems: 1
>> +
>> +  clocks:
>> +    maxItems: 2
>> +
>> +  clock-names:
>> +    description:
>> +      CSI2DC must have two clocks to function correctly. One clock is the
>> +      peripheral clock for the inside functionality of the hardware block.
>> +      This is named 'pclk'. The second clock must be the cross domain clock,
>> +      in which CSI2DC will perform clock crossing. This clock must be fed
>> +      by the next controller in pipeline, which usually is a sensor controller.
>> +      Normally this clock should be given by this sensor controller who
>> +      is also a clock source. This clock is named 'scck', sensor controller clock.
>> +    items:
>> +      - const: pclk
>> +      - const: scck
>> +
>> +  ports:
>> +    type: object
>> +    description:
>> +      List of ports
>> +
>> +    properties:
>> +      port@0:
>> +        type: object
>> +        description:
>> +          Input port node, single endpoint describing the input pad.
>> +      port@1:
>> +        type: object
>> +        description:
>> +          Output port node, single endpoint, describing the output pad.
>> +
>> +additionalProperties: false
>> +
>> +required:
>> +  - compatible
>> +  - reg
>> +  - clocks
>> +  - clock-names
>> +  - ports
>> +
>> +examples:
>> +  - |
>> +    csi2dc@e1404000 {
>> +        compatible = "microchip,sama7g5-csi2dc";
>> +        reg = <0xe1404000 0x500>;
>> +        clocks = <&pclk>, <&scck>;
>> +        clock-names = "pclk", "scck";
>> +
>> +        ports {
>> +               #address-cells = <1>;
>> +               #size-cells = <0>;
>> +               port@0 {
>> +                       reg = <0>; /* must be 0, first child port */
>> +                       csi2dc_in: endpoint { /* input from IDI interface */
>> +                               remote-endpoint = <&csi2host_out>;
>> +                       };
>> +               };
>> +
>> +               port@1 {
>> +                       reg = <1>; /* must be 1, second child port */
>> +                       csi2dc_out: endpoint {
>> +                               remote-endpoint = <&xisc_in>; /* output to sensor controller */
>> +                       };
>> +               };
>> +        };
>> +    };
>> +
>> +...
>> --
>> 2.25.1
>>

Re: [PATCH v5 1/3] dt-bindings: media: atmel: csi2dc: add bindings for microchip csi2dc

[Jacopo Mondi]

Hi Eugen,

On Tue, Nov 17, 2020 at 11:14:18AM +0000, Eugen.Hristev@microchip.com wrote:
> On 17.11.2020 12:37, Jacopo Mondi wrote:
> > Hi again,
> >
> > On Thu, Nov 12, 2020 at 03:34:35PM +0200, Eugen Hristev wrote:
> >> Add bindings documentation for Microchip CSI2 Demultiplexer controller.
> >>
> >> CSI2DC is a demultiplexer from Synopsys IDI interface specification to
> >> parallel interface connection or direct memory access.
> >>
> >> Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
> >> ---
> >> Changes in v5:
> >> - modified bindings as per Rob Herring review
> >>
> >> Changes in v4:
> >> - Removed property for inter-line-delay and for clock continuous/non-continuous
> >> - Removed virtual channel by reg for second endpoint
> >>
> >> Changes in v3:
> >> - Removed some text from description, as it was explained in the schema
> >> - fixed other things as per Rob's review
> >> - moved some text inside the schema, like the clock description
> >>
> >> Changes in v2:
> >> - fixed warnings reported by dt_binding_check
> >>
> >>   .../bindings/media/microchip,csi2dc.yaml      | 119 ++++++++++++++++++
> >>   1 file changed, 119 insertions(+)
> >>   create mode 100644 Documentation/devicetree/bindings/media/microchip,csi2dc.yaml
> >>
> >> diff --git a/Documentation/devicetree/bindings/media/microchip,csi2dc.yaml b/Documentation/devicetree/bindings/media/microchip,csi2dc.yaml
> >> new file mode 100644
> >> index 000000000000..e79f0d6ba9db
> >> --- /dev/null
> >> +++ b/Documentation/devicetree/bindings/media/microchip,csi2dc.yaml
> >> @@ -0,0 +1,119 @@
> >> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> >> +%YAML 1.2
> >> +---
> >> +$id: http://devicetree.org/schemas/media/microchip,csi2dc.yaml#
> >> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> >> +
> >> +title: Microchip CSI2 Demux Controller (CSI2DC)
> >> +
> >> +maintainers:
> >> +  - Eugen Hristev <eugen.hristev@microchip.com>
> >> +
> >> +description:
> >> +  CSI2DC - Camera Serial Interface 2 Demux Controller
> >> +
> >> +  CSI2DC is a hardware block that receives incoming data from an IDI interface
> >> +  and filters packets based on their data type and virtual channel identifier,
> >> +  then converts the byte stream into a cross clock domain to a pixel stream
> >> +  to a parallel interface that can be read by a sensor controller.
> >> +
> >> +  CSI2DC provides two pipes, one video pipe and one data pipe. Video pipe
> >> +  is connected to a sensor controller and the data pipe is accessible
> >> +  as a DMA slave port to a DMA controller.
> >> +
> >> +  CSI2DC supports a single 'port' node as a source pad with Synopsys 32-bit
> >> +  IDI interface. The connected endpoint must be a IDI interface compatible
> >> +  device (like Synopsys CSI2HOST) , that can provide 32-bit IDI interface
> >> +  connection as sink pad.
> >> +  For media entity and endpoints please refer to the bindings defined in
> >> +  Documentation/devicetree/bindings/media/video-interfaces.txt.
> >> +  For Synopsys IDI interface please refer to
> >> +  Documentation/devicetree/bindings/media/snps,dw-csi-plat.txt
> >
> > Is it me or this file doesn't exists on the most recent media/master
> > and on v5.10-rc4 ?
>
> Hi Jacopo,
>
> Thanks for reviewing this patch.
> You are right. As I said at some point during the review, actually this
> controller has an input the IDI interface which is not currently in
> kernel. There is a patch series that adds the Synopsys platform driver,
> but nobody worked on it anymore and I use it for testing my driver.
> You can see the last version that was sent here:
>
> https://patchwork.linuxtv.org/project/linux-media/patch/1560280855-18085-2-git-send-email-luis.oliveira@synopsys.com/
>
>
> I sent this series to understand how to improve and how to get my driver
> in kernel, but indeed there are holes, especially this input type of bus
> which is not in the subsystem either.
>
> So how would you suggest to move forward ? Remove the reference to the
> synopsys binding and just leave 'IDI interface' which is undocumented ?

mmm, I see... I was hoping it was a simple CSI-2 tx :)

The Synopsys proposed bindings do not tell much as they don't describe
the csi2host output port. I would just mention "Synopsys IDI
compatible interface" without mentioning a file that cannot be
accessed :)

Thanks
   j

>
> Eugen
>
> >
> >> +
> >> +  CSI2DC supports one 'port' node as sink pad with parallel interface. This is
> >> +  called video pipe.
> >> +  This port has an 'endpoint' can then be used as a source pad for another
> >> +  controller (next in pipeline).
> >> +  Please refer to the bindings defined in
> >> +  Documentation/devicetree/bindings/media/video-interfaces.txt.
> >> +
> >> +  CSI2DC also supports direct access to the data through AHB, via DMA channel,
> >> +  called data pipe.
> >> +  Because of this, the sink 'port' child node (second) is not mandatory.
> >> +  If the sink 'port' child node is missing, only data pipe is available.
> >> +
> >> +properties:
> >> +  compatible:
> >> +    const: microchip,sama7g5-csi2dc
> >> +
> >> +  reg:
> >> +    maxItems: 1
> >> +
> >> +  clocks:
> >> +    maxItems: 2
> >> +
> >> +  clock-names:
> >> +    description:
> >> +      CSI2DC must have two clocks to function correctly. One clock is the
> >> +      peripheral clock for the inside functionality of the hardware block.
> >> +      This is named 'pclk'. The second clock must be the cross domain clock,
> >> +      in which CSI2DC will perform clock crossing. This clock must be fed
> >> +      by the next controller in pipeline, which usually is a sensor controller.
> >> +      Normally this clock should be given by this sensor controller who
> >> +      is also a clock source. This clock is named 'scck', sensor controller clock.
> >> +    items:
> >> +      - const: pclk
> >> +      - const: scck
> >> +
> >> +  ports:
> >> +    type: object
> >> +    description:
> >> +      List of ports
> >> +
> >> +    properties:
> >> +      port@0:
> >> +        type: object
> >> +        description:
> >> +          Input port node, single endpoint describing the input pad.
> >> +      port@1:
> >> +        type: object
> >> +        description:
> >> +          Output port node, single endpoint, describing the output pad.
> >> +
> >> +additionalProperties: false
> >> +
> >> +required:
> >> +  - compatible
> >> +  - reg
> >> +  - clocks
> >> +  - clock-names
> >> +  - ports
> >> +
> >> +examples:
> >> +  - |
> >> +    csi2dc@e1404000 {
> >> +        compatible = "microchip,sama7g5-csi2dc";
> >> +        reg = <0xe1404000 0x500>;
> >> +        clocks = <&pclk>, <&scck>;
> >> +        clock-names = "pclk", "scck";
> >> +
> >> +        ports {
> >> +               #address-cells = <1>;
> >> +               #size-cells = <0>;
> >> +               port@0 {
> >> +                       reg = <0>; /* must be 0, first child port */
> >> +                       csi2dc_in: endpoint { /* input from IDI interface */
> >> +                               remote-endpoint = <&csi2host_out>;
> >> +                       };
> >> +               };
> >> +
> >> +               port@1 {
> >> +                       reg = <1>; /* must be 1, second child port */
> >> +                       csi2dc_out: endpoint {
> >> +                               remote-endpoint = <&xisc_in>; /* output to sensor controller */
> >> +                       };
> >> +               };
> >> +        };
> >> +    };
> >> +
> >> +...
> >> --
> >> 2.25.1
> >>
>