[V7, 0/2] media: i2c: Add support for DW9768 VCM driver

[V7, 0/2] media: i2c: Add support for DW9768 VCM driver

[Dongchun Zhu]

Hello,

This series adds DT bindings and V4L2 sub-device driver for Dongwoon's DW9768,
which is a 10-bit DAC with 100mA output current sink capability.

The driver controls the position with 10-bit DAC data D[9:0] and seperates
two 8-bit registers to control the VCM position as belows.
DAC_MSB: D[9:8](ADDR: 0x03):
     +---+---+---+---+---+---+---+---+
     |---|---|---|---|---|---|D09|D08|
     +---+---+---+---+---+---+---+---+
DAC_LSB: D[7:0](ADDR: 0x04):
     +---+---+---+---+---+---+---+---+
     |D07|D06|D05|D04|D03|D02|D01|D00|
     +---+---+---+---+---+---+---+---+

This driver supports:
 - set DW9768 to standby mode once suspend and turn it back to active if resume
 - set the desired focus via V4L2_CID_FOCUS_ABSOLUTE ctrl

Previous versions of this patch-set can be found here:
v6: https://lore.kernel.org/linux-media/20200518132731.20855-1-dongchun.zhu@mediatek.com/
v5: https://lore.kernel.org/linux-media/20200502161727.30463-1-dongchun.zhu@mediatek.com/
v4: https://lore.kernel.org/linux-media/20200330123634.363-1-dongchun.zhu@mediatek.com/
v3: https://lore.kernel.org/linux-media/20200228155958.20657-1-dongchun.zhu@mediatek.com/
v2: https://lore.kernel.org/linux-media/20190905072142.14606-1-dongchun.zhu@mediatek.com/
v1: https://lore.kernel.org/linux-media/20190708100641.2702-1-dongchun.zhu@mediatek.com/

Mainly changes of v7 are addressing comments from Rob, Sakari, Tomasz.
Compared to v6:
 - Refine DT bindings
 - Use i2c_smbus_read_byte_data() directly to replace of dw9768_read_smbus()
 - Calculate operation time based on the configured board-specific DT settings
 - Abstract async register error handling case
 - Fix other review comments in v6

Please review.
Thanks.

Dongchun Zhu (2):
  media: dt-bindings: media: i2c: Document DW9768 bindings
  media: i2c: dw9768: Add DW9768 VCM driver

 .../bindings/media/i2c/dongwoon,dw9768.yaml        | 100 ++++
 MAINTAINERS                                        |   8 +
 drivers/media/i2c/Kconfig                          |  13 +
 drivers/media/i2c/Makefile                         |   1 +
 drivers/media/i2c/dw9768.c                         | 566 +++++++++++++++++++++
 5 files changed, 688 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/media/i2c/dongwoon,dw9768.yaml
 create mode 100644 drivers/media/i2c/dw9768.c

-- 
2.9.2

[V7, 1/2] media: dt-bindings: media: i2c: Document DW9768 bindings

[Dongchun Zhu]

Add DeviceTree binding documentation for Dongwoon Anatech DW9768 voice
coil actuator.

Signed-off-by: Dongchun Zhu <dongchun.zhu@mediatek.com>
---
 .../bindings/media/i2c/dongwoon,dw9768.yaml        | 100 +++++++++++++++++++++
 MAINTAINERS                                        |   7 ++
 2 files changed, 107 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/media/i2c/dongwoon,dw9768.yaml

diff --git a/Documentation/devicetree/bindings/media/i2c/dongwoon,dw9768.yaml b/Documentation/devicetree/bindings/media/i2c/dongwoon,dw9768.yaml
new file mode 100644
index 0000000..cb96e95
--- /dev/null
+++ b/Documentation/devicetree/bindings/media/i2c/dongwoon,dw9768.yaml
@@ -0,0 +1,100 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+# Copyright (c) 2020 MediaTek Inc.
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/media/i2c/dongwoon,dw9768.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Dongwoon Anatech DW9768 Voice Coil Motor (VCM) Lens Device Tree Bindings
+
+maintainers:
+  - Dongchun Zhu <dongchun.zhu@mediatek.com>
+
+description: |-
+  The Dongwoon DW9768 is a single 10-bit digital-to-analog (DAC) converter
+  with 100 mA output current sink capability. VCM current is controlled with
+  a linear mode driver. The DAC is controlled via a 2-wire (I2C-compatible)
+  serial interface that operates at clock rates up to 1MHz. This chip
+  integrates Advanced Actuator Control (AAC) technology and is intended for
+  driving voice coil lenses in camera modules.
+
+properties:
+  compatible:
+    enum:
+      - dongwoon,dw9768 # for DW9768 VCM
+      - giantec,gt9769  # for GT9769 VCM
+
+  reg:
+    maxItems: 1
+
+  vin-supply:
+    description:
+      Definition of the regulator used as Digital I/O voltage supply.
+
+  vdd-supply:
+    description:
+      Definition of the regulator used as Digital core voltage supply.
+
+  dongwoon,aac-mode:
+    description:
+      Indication of AAC mode select.
+    allOf:
+      - $ref: "/schemas/types.yaml#/definitions/uint32"
+      - enum:
+          - 1    #  AAC2 mode(operation time# 0.48 x Tvib)
+          - 2    #  AAC3 mode(operation time# 0.70 x Tvib)
+          - 3    #  AAC4 mode(operation time# 0.75 x Tvib)
+          - 5    #  AAC8 mode(operation time# 1.13 x Tvib)
+        default: 2
+
+  dongwoon,aac-timing:
+    description:
+      Number of AAC Timing count that controlled by one 6-bit period of
+      vibration register AACT[5:0], the unit of which is 100 us.
+    allOf:
+      - $ref: "/schemas/types.yaml#/definitions/uint32"
+      - default: 0x20
+        minimum: 0x00
+        maximum: 0x3f
+
+  dongwoon,clock-presc:
+    description:
+      Indication of VCM internal clock dividing rate select, as one multiple
+      factor to calculate VCM ring periodic time Tvib.
+    allOf:
+      - $ref: "/schemas/types.yaml#/definitions/uint32"
+      - enum:
+          - 0    #  Dividing Rate -  2
+          - 1    #  Dividing Rate -  1
+          - 2    #  Dividing Rate -  1/2
+          - 3    #  Dividing Rate -  1/4
+          - 4    #  Dividing Rate -  8
+          - 5    #  Dividing Rate -  4
+        default: 1
+
+required:
+  - compatible
+  - reg
+  - vin-supply
+  - vdd-supply
+
+additionalProperties: false
+
+examples:
+  - |
+
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        dw9768: camera-lens@c {
+            compatible = "dongwoon,dw9768";
+            reg = <0x0c>;
+
+            vin-supply = <&mt6358_vcamio_reg>;
+            vdd-supply = <&mt6358_vcama2_reg>;
+            dongwoon,aac-timing = <0x39>;
+        };
+    };
+
+...
diff --git a/MAINTAINERS b/MAINTAINERS
index e64e5db..8d72c41 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5151,6 +5151,13 @@ T:	git git://linuxtv.org/media_tree.git
 F:	Documentation/devicetree/bindings/media/i2c/dongwoon,dw9714.txt
 F:	drivers/media/i2c/dw9714.c
 
+DONGWOON DW9768 LENS VOICE COIL DRIVER
+M:	Dongchun Zhu <dongchun.zhu@mediatek.com>
+L:	linux-media@vger.kernel.org
+S:	Maintained
+T:	git git://linuxtv.org/media_tree.git
+F:	Documentation/devicetree/bindings/media/i2c/dongwoon,dw9768.yaml
+
 DONGWOON DW9807 LENS VOICE COIL DRIVER
 M:	Sakari Ailus <sakari.ailus@linux.intel.com>
 L:	linux-media@vger.kernel.org
-- 
2.9.2

[V7, 2/2] media: i2c: dw9768: Add DW9768 VCM driver

[Dongchun Zhu]

Add a V4L2 sub-device driver for DW9768 voice coil motor, providing
control to set the desired focus via IIC serial interface.

Signed-off-by: Dongchun Zhu <dongchun.zhu@mediatek.com>
---
 MAINTAINERS                |   1 +
 drivers/media/i2c/Kconfig  |  13 ++
 drivers/media/i2c/Makefile |   1 +
 drivers/media/i2c/dw9768.c | 566 +++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 581 insertions(+)
 create mode 100644 drivers/media/i2c/dw9768.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 8d72c41..c92dc99 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5157,6 +5157,7 @@ L:	linux-media@vger.kernel.org
 S:	Maintained
 T:	git git://linuxtv.org/media_tree.git
 F:	Documentation/devicetree/bindings/media/i2c/dongwoon,dw9768.yaml
+F:	drivers/media/i2c/dw9768.c
 
 DONGWOON DW9807 LENS VOICE COIL DRIVER
 M:	Sakari Ailus <sakari.ailus@linux.intel.com>
diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
index 125d596..afdf994 100644
--- a/drivers/media/i2c/Kconfig
+++ b/drivers/media/i2c/Kconfig
@@ -1040,6 +1040,19 @@ config VIDEO_DW9714
 	  capability. This is designed for linear control of
 	  voice coil motors, controlled via I2C serial interface.
 
+config VIDEO_DW9768
+	tristate "DW9768 lens voice coil support"
+	depends on I2C && VIDEO_V4L2
+	depends on PM
+	select MEDIA_CONTROLLER
+	select VIDEO_V4L2_SUBDEV_API
+	select V4L2_FWNODE
+	help
+	  This is a driver for the DW9768 camera lens voice coil.
+	  DW9768 is a 10 bit DAC with 100mA output current sink
+	  capability. This is designed for linear control of
+	  voice coil motors, controlled via I2C serial interface.
+
 config VIDEO_DW9807_VCM
 	tristate "DW9807 lens voice coil support"
 	depends on I2C && VIDEO_V4L2 && MEDIA_CONTROLLER
diff --git a/drivers/media/i2c/Makefile b/drivers/media/i2c/Makefile
index 77bf7d0..4057476 100644
--- a/drivers/media/i2c/Makefile
+++ b/drivers/media/i2c/Makefile
@@ -24,6 +24,7 @@ obj-$(CONFIG_VIDEO_SAA6752HS) += saa6752hs.o
 obj-$(CONFIG_VIDEO_AD5820)  += ad5820.o
 obj-$(CONFIG_VIDEO_AK7375)  += ak7375.o
 obj-$(CONFIG_VIDEO_DW9714)  += dw9714.o
+obj-$(CONFIG_VIDEO_DW9768)  += dw9768.o
 obj-$(CONFIG_VIDEO_DW9807_VCM)  += dw9807-vcm.o
 obj-$(CONFIG_VIDEO_ADV7170) += adv7170.o
 obj-$(CONFIG_VIDEO_ADV7175) += adv7175.o
diff --git a/drivers/media/i2c/dw9768.c b/drivers/media/i2c/dw9768.c
new file mode 100644
index 0000000..f34a8ed
--- /dev/null
+++ b/drivers/media/i2c/dw9768.c
@@ -0,0 +1,566 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2020 MediaTek Inc.
+
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/pm_runtime.h>
+#include <linux/regulator/consumer.h>
+#include <media/v4l2-async.h>
+#include <media/v4l2-ctrls.h>
+#include <media/v4l2-device.h>
+#include <media/v4l2-fwnode.h>
+#include <media/v4l2-subdev.h>
+
+#define DW9768_NAME				"dw9768"
+#define DW9768_MAX_FOCUS_POS			(1024 - 1)
+/*
+ * This sets the minimum granularity for the focus positions.
+ * A value of 1 gives maximum accuracy for a desired focus position
+ */
+#define DW9768_FOCUS_STEPS			1
+
+/*
+ * Ring control and Power control register
+ * Bit[1] RING_EN
+ * 0: Direct mode
+ * 1: AAC mode (ringing control mode)
+ * Bit[0] PD
+ * 0: Normal operation mode
+ * 1: Power down mode
+ * DW9768 requires waiting time of Topr after PD reset takes place.
+ */
+#define DW9768_RING_PD_CONTROL_REG		0x02
+#define DW9768_PD_MODE_OFF			0x00
+#define DW9768_PD_MODE_EN			BIT(0)
+#define DW9768_AAC_MODE_EN			BIT(1)
+
+/*
+ * DW9768 separates two registers to control the VCM position.
+ * One for MSB value, another is LSB value.
+ * DAC_MSB: D[9:8] (ADD: 0x03)
+ * DAC_LSB: D[7:0] (ADD: 0x04)
+ * D[9:0] DAC data input: positive output current = D[9:0] / 1023 * 100[mA]
+ */
+#define DW9768_MSB_ADDR				0x03
+#define DW9768_LSB_ADDR				0x04
+#define DW9768_STATUS_ADDR			0x05
+
+/*
+ * AAC mode control & prescale register
+ * Bit[7:5] Namely AC[2:0], decide the VCM mode and operation time.
+ * 001 AAC2 0.48 x Tvib
+ * 010 AAC3 0.70 x Tvib
+ * 011 AAC4 0.75 x Tvib
+ * 101 AAC8 1.13 x Tvib
+ * Bit[2:0] Namely PRESC[2:0], set the internal clock dividing rate as follow.
+ * 000 2
+ * 001 1
+ * 010 1/2
+ * 011 1/4
+ * 100 8
+ * 101 4
+ */
+#define DW9768_AAC_PRESC_REG			0x06
+#define DW9768_AAC_MODE_SEL_MASK		GENMASK(7, 5)
+#define DW9768_CLOCK_PRE_SCALE_SEL_MASK		GENMASK(2, 0)
+
+/*
+ * VCM period of vibration register
+ * Bit[5:0] Defined as VCM rising periodic time (Tvib) together with PRESC[2:0]
+ * Tvib = (6.3ms + AACT[5:0] * 0.1ms) * Dividing Rate
+ * Dividing Rate is the internal clock dividing rate that is defined at
+ * PRESCALE register (ADD: 0x06)
+ */
+#define DW9768_AAC_TIME_REG			0x07
+
+/*
+ * DW9768 requires waiting time (delay time) of t_OPR after power-up,
+ * or in the case of PD reset taking place.
+ */
+#define DW9768_T_OPR_US				1000
+#define DW9768_Tvib_MS_BASE10			(64 - 1)
+#define DW9768_AAC_MODE_DEFAULT			2
+#define DW9768_AAC_TIME_DEFAULT			0x20
+#define DW9768_CLOCK_PRE_SCALE_DEFAULT		1
+
+/*
+ * This acts as the minimum granularity of lens movement.
+ * Keep this value power of 2, so the control steps can be
+ * uniformly adjusted for gradual lens movement, with desired
+ * number of control steps.
+ */
+#define DW9768_MOVE_STEPS			16
+
+static const char * const dw9768_supply_names[] = {
+	"vin",	/* Digital I/O power */
+	"vdd",	/* Digital core power */
+};
+
+/* dw9768 device structure */
+struct dw9768 {
+	struct regulator_bulk_data supplies[ARRAY_SIZE(dw9768_supply_names)];
+	struct v4l2_ctrl_handler ctrls;
+	struct v4l2_ctrl *focus;
+	struct v4l2_subdev sd;
+
+	u32 aac_mode;
+	u32 aac_timing;
+	u32 clock_presc;
+};
+
+static inline struct dw9768 *sd_to_dw9768(struct v4l2_subdev *subdev)
+{
+	return container_of(subdev, struct dw9768, sd);
+}
+
+struct regval_list {
+	u8 reg_num;
+	u8 value;
+};
+
+struct dw9768_aac_mode_ot_multi {
+	u32 aac_mode_enum;
+	u32 ot_multi_base100;
+};
+
+struct dw9768_clk_presc_dividing_rate {
+	u32 clk_presc_enum;
+	u32 dividing_rate_base100;
+};
+
+static const struct dw9768_aac_mode_ot_multi aac_mode_ot_multi[] = {
+	{1,  48},
+	{2,  70},
+	{3,  75},
+	{5, 113},
+};
+
+static const struct dw9768_clk_presc_dividing_rate presc_dividing_rate[] = {
+	{0, 200},
+	{1, 100},
+	{2,  50},
+	{3,  25},
+	{4, 800},
+	{5, 400},
+};
+
+static u32 dw9768_find_ot_multi(u32 aac_mode_param)
+{
+	u32 cur_ot_multi_base100 = 70;
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(aac_mode_ot_multi); i++) {
+		if (aac_mode_ot_multi[i].aac_mode_enum == aac_mode_param) {
+			cur_ot_multi_base100 =
+				aac_mode_ot_multi[i].ot_multi_base100;
+		}
+	}
+
+	return cur_ot_multi_base100;
+}
+
+static u32 dw9768_find_dividing_rate(u32 presc_param)
+{
+	u32 cur_clk_dividing_rate_base100 = 100;
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(presc_dividing_rate); i++) {
+		if (presc_dividing_rate[i].clk_presc_enum == presc_param) {
+			cur_clk_dividing_rate_base100 =
+				presc_dividing_rate[i].dividing_rate_base100;
+		}
+	}
+
+	return cur_clk_dividing_rate_base100;
+}
+
+/*
+ * DW9768_AAC_PRESC_REG & DW9768_AAC_TIME_REG determine VCM operation time.
+ * For current VCM mode: AAC3, Operation Time would be 0.70 x Tvib.
+ * Tvib = (6.3ms + AACT[5:0] * 0.1MS) * Dividing Rate.
+ * Below is calculation of the operation delay for each step.
+ */
+static inline u32 dw9768_cal_move_delay(u32 aac_mode_param, u32 presc_param,
+					u32 aac_timing_param)
+{
+	u32 Tvib_us;
+	u32 ot_multi_base100;
+	u32 clk_dividing_rate_base100;
+
+	ot_multi_base100 = dw9768_find_ot_multi(aac_mode_param);
+
+	clk_dividing_rate_base100 = dw9768_find_dividing_rate(presc_param);
+
+	Tvib_us = (DW9768_Tvib_MS_BASE10 + aac_timing_param) *
+		  clk_dividing_rate_base100;
+
+	return Tvib_us * ot_multi_base100;
+}
+
+static int dw9768_mod_reg(struct dw9768 *dw9768, u8 reg, u8 mask, u8 val)
+{
+	struct i2c_client *client = v4l2_get_subdevdata(&dw9768->sd);
+	int ret;
+
+	ret = i2c_smbus_read_byte_data(client, reg);
+	if (ret < 0)
+		return ret;
+
+	val = ((unsigned char)ret & ~mask) | (val & mask);
+
+	return i2c_smbus_write_byte_data(client, reg, val);
+}
+
+static int dw9768_set_dac(struct dw9768 *dw9768, u16 val)
+{
+	struct i2c_client *client = v4l2_get_subdevdata(&dw9768->sd);
+
+	/* Write VCM position to registers */
+	return i2c_smbus_write_word_swapped(client, DW9768_MSB_ADDR, val);
+}
+
+static int dw9768_init(struct dw9768 *dw9768)
+{
+	struct i2c_client *client = v4l2_get_subdevdata(&dw9768->sd);
+	u32 move_delay_us;
+	int ret, val;
+
+	/* Reset DW9768_RING_PD_CONTROL_REG to default status 0x00 */
+	ret = i2c_smbus_write_byte_data(client, DW9768_RING_PD_CONTROL_REG,
+					DW9768_PD_MODE_OFF);
+	if (ret < 0)
+		return ret;
+
+	/*
+	 * DW9769 requires waiting delay time of t_OPR
+	 * after PD reset takes place.
+	 */
+	usleep_range(DW9768_T_OPR_US, DW9768_T_OPR_US + 100);
+
+	/* Set DW9768_RING_PD_CONTROL_REG to DW9768_AAC_MODE_EN(0x01) */
+	ret = i2c_smbus_write_byte_data(client, DW9768_RING_PD_CONTROL_REG,
+					DW9768_AAC_MODE_EN);
+	if (ret < 0)
+		return ret;
+
+	/* Set AAC mode */
+	ret = dw9768_mod_reg(dw9768, DW9768_AAC_PRESC_REG,
+			     DW9768_AAC_MODE_SEL_MASK,
+			     dw9768->aac_mode << 5);
+	if (ret < 0)
+		return ret;
+
+	/* Set clock presc */
+	if (dw9768->clock_presc != DW9768_CLOCK_PRE_SCALE_DEFAULT) {
+		ret = dw9768_mod_reg(dw9768, DW9768_AAC_PRESC_REG,
+				     DW9768_CLOCK_PRE_SCALE_SEL_MASK,
+				     dw9768->clock_presc);
+		if (ret < 0)
+			return ret;
+	}
+
+	/* Set AAC Timing */
+	if (dw9768->aac_timing != DW9768_AAC_TIME_DEFAULT) {
+		ret = i2c_smbus_write_byte_data(client, DW9768_AAC_TIME_REG,
+						dw9768->aac_timing);
+		if (ret < 0)
+			return ret;
+	}
+
+	move_delay_us = dw9768_cal_move_delay(dw9768->aac_mode,
+					      dw9768->clock_presc,
+					      dw9768->aac_timing) / 100;
+
+	for (val = dw9768->focus->val % DW9768_MOVE_STEPS;
+	     val <= dw9768->focus->val;
+	     val += DW9768_MOVE_STEPS) {
+		ret = dw9768_set_dac(dw9768, val);
+		if (ret) {
+			dev_err(&client->dev, "%s I2C failure: %d",
+				__func__, ret);
+			return ret;
+		}
+		usleep_range(move_delay_us, move_delay_us + 1000);
+	}
+
+	return 0;
+}
+
+static int dw9768_release(struct dw9768 *dw9768)
+{
+	struct i2c_client *client = v4l2_get_subdevdata(&dw9768->sd);
+	u32 move_delay_us = dw9768_cal_move_delay(dw9768->aac_mode,
+						  dw9768->clock_presc,
+						  dw9768->aac_timing) / 100;
+	int ret, val;
+
+	val = round_down(dw9768->focus->val, DW9768_MOVE_STEPS);
+	for ( ; val >= 0; val -= DW9768_MOVE_STEPS) {
+		ret = dw9768_set_dac(dw9768, val);
+		if (ret) {
+			dev_err(&client->dev, "I2C write fail: %d", ret);
+			return ret;
+		}
+		usleep_range(move_delay_us, move_delay_us + 1000);
+	}
+
+	ret = i2c_smbus_write_byte_data(client, DW9768_RING_PD_CONTROL_REG,
+					DW9768_PD_MODE_EN);
+	if (ret < 0)
+		return ret;
+
+	/*
+	 * DW9769 requires waiting delay time of t_OPR
+	 * after PD reset takes place.
+	 */
+	usleep_range(DW9768_T_OPR_US, DW9768_T_OPR_US + 100);
+
+	return 0;
+}
+
+static int dw9768_runtime_suspend(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct v4l2_subdev *sd = i2c_get_clientdata(client);
+	struct dw9768 *dw9768 = sd_to_dw9768(sd);
+
+	dw9768_release(dw9768);
+	regulator_bulk_disable(ARRAY_SIZE(dw9768_supply_names),
+			       dw9768->supplies);
+
+	return 0;
+}
+
+static int dw9768_runtime_resume(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct v4l2_subdev *sd = i2c_get_clientdata(client);
+	struct dw9768 *dw9768 = sd_to_dw9768(sd);
+	int ret;
+
+	ret = regulator_bulk_enable(ARRAY_SIZE(dw9768_supply_names),
+				    dw9768->supplies);
+	if (ret < 0) {
+		dev_err(dev, "failed to enable regulators\n");
+		return ret;
+	}
+
+	/*
+	 * The datasheet refers to t_OPR that needs to be waited before sending
+	 * I2C commands after power-up.
+	 */
+	usleep_range(DW9768_T_OPR_US, DW9768_T_OPR_US + 100);
+
+	ret = dw9768_init(dw9768);
+	if (ret < 0)
+		goto disable_regulator;
+
+	return 0;
+
+disable_regulator:
+	regulator_bulk_disable(ARRAY_SIZE(dw9768_supply_names),
+			       dw9768->supplies);
+
+	return ret;
+}
+
+static int dw9768_set_ctrl(struct v4l2_ctrl *ctrl)
+{
+	struct dw9768 *dw9768 = container_of(ctrl->handler,
+					     struct dw9768, ctrls);
+
+	if (ctrl->id == V4L2_CID_FOCUS_ABSOLUTE)
+		return dw9768_set_dac(dw9768, ctrl->val);
+
+	return 0;
+}
+
+static const struct v4l2_ctrl_ops dw9768_ctrl_ops = {
+	.s_ctrl = dw9768_set_ctrl,
+};
+
+static int dw9768_open(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh)
+{
+	int ret;
+
+	ret = pm_runtime_get_sync(sd->dev);
+	if (ret < 0) {
+		pm_runtime_put_noidle(sd->dev);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int dw9768_close(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh)
+{
+	pm_runtime_put(sd->dev);
+
+	return 0;
+}
+
+static const struct v4l2_subdev_internal_ops dw9768_int_ops = {
+	.open = dw9768_open,
+	.close = dw9768_close,
+};
+
+static const struct v4l2_subdev_ops dw9768_ops = { };
+
+static int dw9768_init_controls(struct dw9768 *dw9768)
+{
+	struct v4l2_ctrl_handler *hdl = &dw9768->ctrls;
+	const struct v4l2_ctrl_ops *ops = &dw9768_ctrl_ops;
+
+	v4l2_ctrl_handler_init(hdl, 1);
+
+	dw9768->focus = v4l2_ctrl_new_std(hdl, ops, V4L2_CID_FOCUS_ABSOLUTE, 0,
+					  DW9768_MAX_FOCUS_POS,
+					  DW9768_FOCUS_STEPS, 0);
+
+	if (hdl->error)
+		return hdl->error;
+
+	dw9768->sd.ctrl_handler = hdl;
+
+	return 0;
+}
+
+static int dw9768_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct dw9768 *dw9768;
+	u32 aac_mode_select;
+	u32 aac_timing_select;
+	u32 clock_presc_select;
+	unsigned int i;
+	int ret;
+
+	dw9768 = devm_kzalloc(dev, sizeof(*dw9768), GFP_KERNEL);
+	if (!dw9768)
+		return -ENOMEM;
+
+	/* Initialize subdev */
+	v4l2_i2c_subdev_init(&dw9768->sd, client, &dw9768_ops);
+
+	dw9768->aac_mode = DW9768_AAC_MODE_DEFAULT;
+	dw9768->aac_timing = DW9768_AAC_TIME_DEFAULT;
+	dw9768->clock_presc = DW9768_CLOCK_PRE_SCALE_DEFAULT;
+
+	/* Optional indication of AAC mode select */
+	ret = fwnode_property_read_u32(dev_fwnode(dev), "dongwoon,aac-mode",
+				       &aac_mode_select);
+
+	if (!ret)
+		dw9768->aac_mode = aac_mode_select;
+
+	/* Optional indication of clock pre-scale select */
+	ret = fwnode_property_read_u32(dev_fwnode(dev), "dongwoon,clock-presc",
+				       &clock_presc_select);
+
+	if (!ret)
+		dw9768->clock_presc = clock_presc_select;
+
+	/* Optional indication of AAC Timing */
+	ret = fwnode_property_read_u32(dev_fwnode(dev), "dongwoon,aac-timing",
+				       &aac_timing_select);
+
+	if (!ret)
+		dw9768->aac_timing = aac_timing_select;
+
+	for (i = 0; i < ARRAY_SIZE(dw9768_supply_names); i++)
+		dw9768->supplies[i].supply = dw9768_supply_names[i];
+
+	ret = devm_regulator_bulk_get(dev, ARRAY_SIZE(dw9768_supply_names),
+				      dw9768->supplies);
+	if (ret) {
+		dev_err(dev, "failed to get regulators\n");
+		return ret;
+	}
+
+	/* Initialize controls */
+	ret = dw9768_init_controls(dw9768);
+	if (ret)
+		goto err_free_handler;
+
+	/* Initialize subdev */
+	dw9768->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
+	dw9768->sd.internal_ops = &dw9768_int_ops;
+
+	ret = media_entity_pads_init(&dw9768->sd.entity, 0, NULL);
+	if (ret < 0)
+		goto err_free_handler;
+
+	dw9768->sd.entity.function = MEDIA_ENT_F_LENS;
+
+	pm_runtime_enable(dev);
+	if (!pm_runtime_enabled(dev)) {
+		ret = dw9768_runtime_resume(dev);
+		if (ret < 0) {
+			dev_err(dev, "failed to power on: %d\n", ret);
+			goto err_clean_entity;
+		}
+	}
+
+	ret = v4l2_async_register_subdev(&dw9768->sd);
+	if (ret < 0) {
+		dev_err(dev, "failed to register V4L2 subdev: %d", ret);
+		goto error_async_register;
+	}
+
+	return 0;
+
+error_async_register:
+	if (!pm_runtime_enabled(dev))
+		dw9768_runtime_suspend(dev);
+err_clean_entity:
+	media_entity_cleanup(&dw9768->sd.entity);
+err_free_handler:
+	v4l2_ctrl_handler_free(&dw9768->ctrls);
+
+	return ret;
+}
+
+static int dw9768_remove(struct i2c_client *client)
+{
+	struct v4l2_subdev *sd = i2c_get_clientdata(client);
+	struct dw9768 *dw9768 = sd_to_dw9768(sd);
+
+	v4l2_async_unregister_subdev(&dw9768->sd);
+	v4l2_ctrl_handler_free(&dw9768->ctrls);
+	media_entity_cleanup(&dw9768->sd.entity);
+	pm_runtime_disable(&client->dev);
+	if (!pm_runtime_status_suspended(&client->dev))
+		dw9768_runtime_suspend(&client->dev);
+	pm_runtime_set_suspended(&client->dev);
+
+	return 0;
+}
+
+static const struct of_device_id dw9768_of_table[] = {
+	{ .compatible = "dongwoon,dw9768" },
+	{ .compatible = "giantec,gt9769" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, dw9768_of_table);
+
+static const struct dev_pm_ops dw9768_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
+				pm_runtime_force_resume)
+	SET_RUNTIME_PM_OPS(dw9768_runtime_suspend, dw9768_runtime_resume, NULL)
+};
+
+static struct i2c_driver dw9768_i2c_driver = {
+	.driver = {
+		.name = DW9768_NAME,
+		.pm = &dw9768_pm_ops,
+		.of_match_table = dw9768_of_table,
+	},
+	.probe_new  = dw9768_probe,
+	.remove = dw9768_remove,
+};
+module_i2c_driver(dw9768_i2c_driver);
+
+MODULE_AUTHOR("Dongchun Zhu <dongchun.zhu@mediatek.com>");
+MODULE_DESCRIPTION("DW9768 VCM driver");
+MODULE_LICENSE("GPL v2");
-- 
2.9.2

Re: [V7, 2/2] media: i2c: dw9768: Add DW9768 VCM driver

[Sakari Ailus]

Hi Dongchun,

Thank you for the update.

On Fri, Jun 05, 2020 at 06:54:12PM +0800, Dongchun Zhu wrote:
> Add a V4L2 sub-device driver for DW9768 voice coil motor, providing
> control to set the desired focus via IIC serial interface.
> 
> Signed-off-by: Dongchun Zhu <dongchun.zhu@mediatek.com>
> ---
>  MAINTAINERS                |   1 +
>  drivers/media/i2c/Kconfig  |  13 ++
>  drivers/media/i2c/Makefile |   1 +
>  drivers/media/i2c/dw9768.c | 566 +++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 581 insertions(+)
>  create mode 100644 drivers/media/i2c/dw9768.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 8d72c41..c92dc99 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -5157,6 +5157,7 @@ L:	linux-media@vger.kernel.org
>  S:	Maintained
>  T:	git git://linuxtv.org/media_tree.git
>  F:	Documentation/devicetree/bindings/media/i2c/dongwoon,dw9768.yaml
> +F:	drivers/media/i2c/dw9768.c
>  
>  DONGWOON DW9807 LENS VOICE COIL DRIVER
>  M:	Sakari Ailus <sakari.ailus@linux.intel.com>
> diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
> index 125d596..afdf994 100644
> --- a/drivers/media/i2c/Kconfig
> +++ b/drivers/media/i2c/Kconfig
> @@ -1040,6 +1040,19 @@ config VIDEO_DW9714
>  	  capability. This is designed for linear control of
>  	  voice coil motors, controlled via I2C serial interface.
>  
> +config VIDEO_DW9768
> +	tristate "DW9768 lens voice coil support"
> +	depends on I2C && VIDEO_V4L2
> +	depends on PM
> +	select MEDIA_CONTROLLER
> +	select VIDEO_V4L2_SUBDEV_API
> +	select V4L2_FWNODE
> +	help
> +	  This is a driver for the DW9768 camera lens voice coil.
> +	  DW9768 is a 10 bit DAC with 100mA output current sink
> +	  capability. This is designed for linear control of
> +	  voice coil motors, controlled via I2C serial interface.
> +
>  config VIDEO_DW9807_VCM
>  	tristate "DW9807 lens voice coil support"
>  	depends on I2C && VIDEO_V4L2 && MEDIA_CONTROLLER
> diff --git a/drivers/media/i2c/Makefile b/drivers/media/i2c/Makefile
> index 77bf7d0..4057476 100644
> --- a/drivers/media/i2c/Makefile
> +++ b/drivers/media/i2c/Makefile
> @@ -24,6 +24,7 @@ obj-$(CONFIG_VIDEO_SAA6752HS) += saa6752hs.o
>  obj-$(CONFIG_VIDEO_AD5820)  += ad5820.o
>  obj-$(CONFIG_VIDEO_AK7375)  += ak7375.o
>  obj-$(CONFIG_VIDEO_DW9714)  += dw9714.o
> +obj-$(CONFIG_VIDEO_DW9768)  += dw9768.o
>  obj-$(CONFIG_VIDEO_DW9807_VCM)  += dw9807-vcm.o
>  obj-$(CONFIG_VIDEO_ADV7170) += adv7170.o
>  obj-$(CONFIG_VIDEO_ADV7175) += adv7175.o
> diff --git a/drivers/media/i2c/dw9768.c b/drivers/media/i2c/dw9768.c
> new file mode 100644
> index 0000000..f34a8ed
> --- /dev/null
> +++ b/drivers/media/i2c/dw9768.c
> @@ -0,0 +1,566 @@
> +// SPDX-License-Identifier: GPL-2.0
> +// Copyright (c) 2020 MediaTek Inc.
> +
> +#include <linux/delay.h>
> +#include <linux/i2c.h>
> +#include <linux/module.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/regulator/consumer.h>
> +#include <media/v4l2-async.h>
> +#include <media/v4l2-ctrls.h>
> +#include <media/v4l2-device.h>
> +#include <media/v4l2-fwnode.h>
> +#include <media/v4l2-subdev.h>
> +
> +#define DW9768_NAME				"dw9768"
> +#define DW9768_MAX_FOCUS_POS			(1024 - 1)
> +/*
> + * This sets the minimum granularity for the focus positions.
> + * A value of 1 gives maximum accuracy for a desired focus position
> + */
> +#define DW9768_FOCUS_STEPS			1
> +
> +/*
> + * Ring control and Power control register
> + * Bit[1] RING_EN
> + * 0: Direct mode
> + * 1: AAC mode (ringing control mode)
> + * Bit[0] PD
> + * 0: Normal operation mode
> + * 1: Power down mode
> + * DW9768 requires waiting time of Topr after PD reset takes place.
> + */
> +#define DW9768_RING_PD_CONTROL_REG		0x02
> +#define DW9768_PD_MODE_OFF			0x00
> +#define DW9768_PD_MODE_EN			BIT(0)
> +#define DW9768_AAC_MODE_EN			BIT(1)
> +
> +/*
> + * DW9768 separates two registers to control the VCM position.
> + * One for MSB value, another is LSB value.
> + * DAC_MSB: D[9:8] (ADD: 0x03)
> + * DAC_LSB: D[7:0] (ADD: 0x04)
> + * D[9:0] DAC data input: positive output current = D[9:0] / 1023 * 100[mA]
> + */
> +#define DW9768_MSB_ADDR				0x03
> +#define DW9768_LSB_ADDR				0x04
> +#define DW9768_STATUS_ADDR			0x05
> +
> +/*
> + * AAC mode control & prescale register
> + * Bit[7:5] Namely AC[2:0], decide the VCM mode and operation time.
> + * 001 AAC2 0.48 x Tvib
> + * 010 AAC3 0.70 x Tvib
> + * 011 AAC4 0.75 x Tvib
> + * 101 AAC8 1.13 x Tvib
> + * Bit[2:0] Namely PRESC[2:0], set the internal clock dividing rate as follow.
> + * 000 2
> + * 001 1
> + * 010 1/2
> + * 011 1/4
> + * 100 8
> + * 101 4
> + */
> +#define DW9768_AAC_PRESC_REG			0x06
> +#define DW9768_AAC_MODE_SEL_MASK		GENMASK(7, 5)
> +#define DW9768_CLOCK_PRE_SCALE_SEL_MASK		GENMASK(2, 0)
> +
> +/*
> + * VCM period of vibration register
> + * Bit[5:0] Defined as VCM rising periodic time (Tvib) together with PRESC[2:0]
> + * Tvib = (6.3ms + AACT[5:0] * 0.1ms) * Dividing Rate
> + * Dividing Rate is the internal clock dividing rate that is defined at
> + * PRESCALE register (ADD: 0x06)
> + */
> +#define DW9768_AAC_TIME_REG			0x07
> +
> +/*
> + * DW9768 requires waiting time (delay time) of t_OPR after power-up,
> + * or in the case of PD reset taking place.
> + */
> +#define DW9768_T_OPR_US				1000
> +#define DW9768_Tvib_MS_BASE10			(64 - 1)
> +#define DW9768_AAC_MODE_DEFAULT			2
> +#define DW9768_AAC_TIME_DEFAULT			0x20
> +#define DW9768_CLOCK_PRE_SCALE_DEFAULT		1
> +
> +/*
> + * This acts as the minimum granularity of lens movement.
> + * Keep this value power of 2, so the control steps can be
> + * uniformly adjusted for gradual lens movement, with desired
> + * number of control steps.
> + */
> +#define DW9768_MOVE_STEPS			16
> +
> +static const char * const dw9768_supply_names[] = {
> +	"vin",	/* Digital I/O power */
> +	"vdd",	/* Digital core power */
> +};
> +
> +/* dw9768 device structure */
> +struct dw9768 {
> +	struct regulator_bulk_data supplies[ARRAY_SIZE(dw9768_supply_names)];
> +	struct v4l2_ctrl_handler ctrls;
> +	struct v4l2_ctrl *focus;
> +	struct v4l2_subdev sd;
> +
> +	u32 aac_mode;
> +	u32 aac_timing;
> +	u32 clock_presc;
> +};
> +
> +static inline struct dw9768 *sd_to_dw9768(struct v4l2_subdev *subdev)
> +{
> +	return container_of(subdev, struct dw9768, sd);
> +}
> +
> +struct regval_list {
> +	u8 reg_num;
> +	u8 value;
> +};
> +
> +struct dw9768_aac_mode_ot_multi {
> +	u32 aac_mode_enum;
> +	u32 ot_multi_base100;
> +};
> +
> +struct dw9768_clk_presc_dividing_rate {
> +	u32 clk_presc_enum;
> +	u32 dividing_rate_base100;
> +};
> +
> +static const struct dw9768_aac_mode_ot_multi aac_mode_ot_multi[] = {
> +	{1,  48},
> +	{2,  70},
> +	{3,  75},
> +	{5, 113},
> +};
> +
> +static const struct dw9768_clk_presc_dividing_rate presc_dividing_rate[] = {
> +	{0, 200},
> +	{1, 100},
> +	{2,  50},
> +	{3,  25},
> +	{4, 800},
> +	{5, 400},
> +};
> +
> +static u32 dw9768_find_ot_multi(u32 aac_mode_param)
> +{
> +	u32 cur_ot_multi_base100 = 70;
> +	unsigned int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(aac_mode_ot_multi); i++) {
> +		if (aac_mode_ot_multi[i].aac_mode_enum == aac_mode_param) {
> +			cur_ot_multi_base100 =
> +				aac_mode_ot_multi[i].ot_multi_base100;
> +		}
> +	}
> +
> +	return cur_ot_multi_base100;
> +}
> +
> +static u32 dw9768_find_dividing_rate(u32 presc_param)
> +{
> +	u32 cur_clk_dividing_rate_base100 = 100;
> +	unsigned int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(presc_dividing_rate); i++) {
> +		if (presc_dividing_rate[i].clk_presc_enum == presc_param) {
> +			cur_clk_dividing_rate_base100 =
> +				presc_dividing_rate[i].dividing_rate_base100;
> +		}
> +	}
> +
> +	return cur_clk_dividing_rate_base100;
> +}
> +
> +/*
> + * DW9768_AAC_PRESC_REG & DW9768_AAC_TIME_REG determine VCM operation time.
> + * For current VCM mode: AAC3, Operation Time would be 0.70 x Tvib.
> + * Tvib = (6.3ms + AACT[5:0] * 0.1MS) * Dividing Rate.
> + * Below is calculation of the operation delay for each step.
> + */
> +static inline u32 dw9768_cal_move_delay(u32 aac_mode_param, u32 presc_param,
> +					u32 aac_timing_param)
> +{
> +	u32 Tvib_us;
> +	u32 ot_multi_base100;
> +	u32 clk_dividing_rate_base100;
> +
> +	ot_multi_base100 = dw9768_find_ot_multi(aac_mode_param);
> +
> +	clk_dividing_rate_base100 = dw9768_find_dividing_rate(presc_param);
> +
> +	Tvib_us = (DW9768_Tvib_MS_BASE10 + aac_timing_param) *
> +		  clk_dividing_rate_base100;
> +
> +	return Tvib_us * ot_multi_base100;
> +}
> +
> +static int dw9768_mod_reg(struct dw9768 *dw9768, u8 reg, u8 mask, u8 val)
> +{
> +	struct i2c_client *client = v4l2_get_subdevdata(&dw9768->sd);
> +	int ret;
> +
> +	ret = i2c_smbus_read_byte_data(client, reg);
> +	if (ret < 0)
> +		return ret;
> +
> +	val = ((unsigned char)ret & ~mask) | (val & mask);
> +
> +	return i2c_smbus_write_byte_data(client, reg, val);
> +}
> +
> +static int dw9768_set_dac(struct dw9768 *dw9768, u16 val)
> +{
> +	struct i2c_client *client = v4l2_get_subdevdata(&dw9768->sd);
> +
> +	/* Write VCM position to registers */
> +	return i2c_smbus_write_word_swapped(client, DW9768_MSB_ADDR, val);
> +}
> +
> +static int dw9768_init(struct dw9768 *dw9768)
> +{
> +	struct i2c_client *client = v4l2_get_subdevdata(&dw9768->sd);
> +	u32 move_delay_us;
> +	int ret, val;
> +
> +	/* Reset DW9768_RING_PD_CONTROL_REG to default status 0x00 */
> +	ret = i2c_smbus_write_byte_data(client, DW9768_RING_PD_CONTROL_REG,
> +					DW9768_PD_MODE_OFF);
> +	if (ret < 0)
> +		return ret;
> +
> +	/*
> +	 * DW9769 requires waiting delay time of t_OPR
> +	 * after PD reset takes place.
> +	 */
> +	usleep_range(DW9768_T_OPR_US, DW9768_T_OPR_US + 100);
> +
> +	/* Set DW9768_RING_PD_CONTROL_REG to DW9768_AAC_MODE_EN(0x01) */
> +	ret = i2c_smbus_write_byte_data(client, DW9768_RING_PD_CONTROL_REG,
> +					DW9768_AAC_MODE_EN);
> +	if (ret < 0)
> +		return ret;
> +
> +	/* Set AAC mode */
> +	ret = dw9768_mod_reg(dw9768, DW9768_AAC_PRESC_REG,
> +			     DW9768_AAC_MODE_SEL_MASK,
> +			     dw9768->aac_mode << 5);
> +	if (ret < 0)
> +		return ret;
> +
> +	/* Set clock presc */
> +	if (dw9768->clock_presc != DW9768_CLOCK_PRE_SCALE_DEFAULT) {
> +		ret = dw9768_mod_reg(dw9768, DW9768_AAC_PRESC_REG,
> +				     DW9768_CLOCK_PRE_SCALE_SEL_MASK,
> +				     dw9768->clock_presc);
> +		if (ret < 0)
> +			return ret;
> +	}
> +
> +	/* Set AAC Timing */
> +	if (dw9768->aac_timing != DW9768_AAC_TIME_DEFAULT) {
> +		ret = i2c_smbus_write_byte_data(client, DW9768_AAC_TIME_REG,
> +						dw9768->aac_timing);
> +		if (ret < 0)
> +			return ret;
> +	}
> +
> +	move_delay_us = dw9768_cal_move_delay(dw9768->aac_mode,
> +					      dw9768->clock_presc,
> +					      dw9768->aac_timing) / 100;
> +
> +	for (val = dw9768->focus->val % DW9768_MOVE_STEPS;
> +	     val <= dw9768->focus->val;
> +	     val += DW9768_MOVE_STEPS) {
> +		ret = dw9768_set_dac(dw9768, val);
> +		if (ret) {
> +			dev_err(&client->dev, "%s I2C failure: %d",
> +				__func__, ret);
> +			return ret;
> +		}
> +		usleep_range(move_delay_us, move_delay_us + 1000);
> +	}
> +
> +	return 0;
> +}
> +
> +static int dw9768_release(struct dw9768 *dw9768)
> +{
> +	struct i2c_client *client = v4l2_get_subdevdata(&dw9768->sd);
> +	u32 move_delay_us = dw9768_cal_move_delay(dw9768->aac_mode,
> +						  dw9768->clock_presc,
> +						  dw9768->aac_timing) / 100;
> +	int ret, val;
> +
> +	val = round_down(dw9768->focus->val, DW9768_MOVE_STEPS);
> +	for ( ; val >= 0; val -= DW9768_MOVE_STEPS) {
> +		ret = dw9768_set_dac(dw9768, val);
> +		if (ret) {
> +			dev_err(&client->dev, "I2C write fail: %d", ret);
> +			return ret;
> +		}
> +		usleep_range(move_delay_us, move_delay_us + 1000);
> +	}
> +
> +	ret = i2c_smbus_write_byte_data(client, DW9768_RING_PD_CONTROL_REG,
> +					DW9768_PD_MODE_EN);
> +	if (ret < 0)
> +		return ret;
> +
> +	/*
> +	 * DW9769 requires waiting delay time of t_OPR
> +	 * after PD reset takes place.
> +	 */
> +	usleep_range(DW9768_T_OPR_US, DW9768_T_OPR_US + 100);
> +
> +	return 0;
> +}
> +
> +static int dw9768_runtime_suspend(struct device *dev)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct v4l2_subdev *sd = i2c_get_clientdata(client);
> +	struct dw9768 *dw9768 = sd_to_dw9768(sd);
> +
> +	dw9768_release(dw9768);
> +	regulator_bulk_disable(ARRAY_SIZE(dw9768_supply_names),
> +			       dw9768->supplies);
> +
> +	return 0;
> +}
> +
> +static int dw9768_runtime_resume(struct device *dev)

__maybe_unused for this and the suspend callback.

> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct v4l2_subdev *sd = i2c_get_clientdata(client);
> +	struct dw9768 *dw9768 = sd_to_dw9768(sd);
> +	int ret;
> +
> +	ret = regulator_bulk_enable(ARRAY_SIZE(dw9768_supply_names),
> +				    dw9768->supplies);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to enable regulators\n");
> +		return ret;
> +	}
> +
> +	/*
> +	 * The datasheet refers to t_OPR that needs to be waited before sending
> +	 * I2C commands after power-up.
> +	 */
> +	usleep_range(DW9768_T_OPR_US, DW9768_T_OPR_US + 100);
> +
> +	ret = dw9768_init(dw9768);
> +	if (ret < 0)
> +		goto disable_regulator;
> +
> +	return 0;
> +
> +disable_regulator:
> +	regulator_bulk_disable(ARRAY_SIZE(dw9768_supply_names),
> +			       dw9768->supplies);
> +
> +	return ret;
> +}
> +
> +static int dw9768_set_ctrl(struct v4l2_ctrl *ctrl)
> +{
> +	struct dw9768 *dw9768 = container_of(ctrl->handler,
> +					     struct dw9768, ctrls);
> +
> +	if (ctrl->id == V4L2_CID_FOCUS_ABSOLUTE)
> +		return dw9768_set_dac(dw9768, ctrl->val);
> +
> +	return 0;
> +}
> +
> +static const struct v4l2_ctrl_ops dw9768_ctrl_ops = {
> +	.s_ctrl = dw9768_set_ctrl,
> +};
> +
> +static int dw9768_open(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh)
> +{
> +	int ret;
> +
> +	ret = pm_runtime_get_sync(sd->dev);
> +	if (ret < 0) {
> +		pm_runtime_put_noidle(sd->dev);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static int dw9768_close(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh)
> +{
> +	pm_runtime_put(sd->dev);
> +
> +	return 0;
> +}
> +
> +static const struct v4l2_subdev_internal_ops dw9768_int_ops = {
> +	.open = dw9768_open,
> +	.close = dw9768_close,
> +};
> +
> +static const struct v4l2_subdev_ops dw9768_ops = { };
> +
> +static int dw9768_init_controls(struct dw9768 *dw9768)
> +{
> +	struct v4l2_ctrl_handler *hdl = &dw9768->ctrls;
> +	const struct v4l2_ctrl_ops *ops = &dw9768_ctrl_ops;
> +
> +	v4l2_ctrl_handler_init(hdl, 1);
> +
> +	dw9768->focus = v4l2_ctrl_new_std(hdl, ops, V4L2_CID_FOCUS_ABSOLUTE, 0,
> +					  DW9768_MAX_FOCUS_POS,
> +					  DW9768_FOCUS_STEPS, 0);
> +
> +	if (hdl->error)
> +		return hdl->error;
> +
> +	dw9768->sd.ctrl_handler = hdl;
> +
> +	return 0;
> +}
> +
> +static int dw9768_probe(struct i2c_client *client)
> +{
> +	struct device *dev = &client->dev;
> +	struct dw9768 *dw9768;
> +	u32 aac_mode_select;
> +	u32 aac_timing_select;
> +	u32 clock_presc_select;
> +	unsigned int i;
> +	int ret;
> +
> +	dw9768 = devm_kzalloc(dev, sizeof(*dw9768), GFP_KERNEL);
> +	if (!dw9768)
> +		return -ENOMEM;
> +
> +	/* Initialize subdev */
> +	v4l2_i2c_subdev_init(&dw9768->sd, client, &dw9768_ops);
> +
> +	dw9768->aac_mode = DW9768_AAC_MODE_DEFAULT;
> +	dw9768->aac_timing = DW9768_AAC_TIME_DEFAULT;
> +	dw9768->clock_presc = DW9768_CLOCK_PRE_SCALE_DEFAULT;
> +
> +	/* Optional indication of AAC mode select */
> +	ret = fwnode_property_read_u32(dev_fwnode(dev), "dongwoon,aac-mode",
> +				       &aac_mode_select);
> +
> +	if (!ret)
> +		dw9768->aac_mode = aac_mode_select;
> +
> +	/* Optional indication of clock pre-scale select */
> +	ret = fwnode_property_read_u32(dev_fwnode(dev), "dongwoon,clock-presc",
> +				       &clock_presc_select);
> +
> +	if (!ret)
> +		dw9768->clock_presc = clock_presc_select;
> +
> +	/* Optional indication of AAC Timing */
> +	ret = fwnode_property_read_u32(dev_fwnode(dev), "dongwoon,aac-timing",
> +				       &aac_timing_select);
> +
> +	if (!ret)
> +		dw9768->aac_timing = aac_timing_select;

You can assign the defaults to the dw9768 struct and use the fwnode
property API to read the properties into the same fields. No return values
need to be checked.

> +
> +	for (i = 0; i < ARRAY_SIZE(dw9768_supply_names); i++)
> +		dw9768->supplies[i].supply = dw9768_supply_names[i];
> +
> +	ret = devm_regulator_bulk_get(dev, ARRAY_SIZE(dw9768_supply_names),
> +				      dw9768->supplies);
> +	if (ret) {
> +		dev_err(dev, "failed to get regulators\n");
> +		return ret;
> +	}
> +
> +	/* Initialize controls */
> +	ret = dw9768_init_controls(dw9768);
> +	if (ret)
> +		goto err_free_handler;
> +
> +	/* Initialize subdev */
> +	dw9768->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
> +	dw9768->sd.internal_ops = &dw9768_int_ops;
> +
> +	ret = media_entity_pads_init(&dw9768->sd.entity, 0, NULL);
> +	if (ret < 0)
> +		goto err_free_handler;
> +
> +	dw9768->sd.entity.function = MEDIA_ENT_F_LENS;
> +
> +	pm_runtime_enable(dev);
> +	if (!pm_runtime_enabled(dev)) {
> +		ret = dw9768_runtime_resume(dev);
> +		if (ret < 0) {
> +			dev_err(dev, "failed to power on: %d\n", ret);
> +			goto err_clean_entity;
> +		}
> +	}
> +
> +	ret = v4l2_async_register_subdev(&dw9768->sd);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to register V4L2 subdev: %d", ret);
> +		goto error_async_register;
> +	}
> +
> +	return 0;
> +
> +error_async_register:
> +	if (!pm_runtime_enabled(dev))
> +		dw9768_runtime_suspend(dev);
> +err_clean_entity:
> +	media_entity_cleanup(&dw9768->sd.entity);
> +err_free_handler:
> +	v4l2_ctrl_handler_free(&dw9768->ctrls);
> +
> +	return ret;
> +}
> +
> +static int dw9768_remove(struct i2c_client *client)
> +{
> +	struct v4l2_subdev *sd = i2c_get_clientdata(client);
> +	struct dw9768 *dw9768 = sd_to_dw9768(sd);
> +
> +	v4l2_async_unregister_subdev(&dw9768->sd);
> +	v4l2_ctrl_handler_free(&dw9768->ctrls);
> +	media_entity_cleanup(&dw9768->sd.entity);
> +	pm_runtime_disable(&client->dev);
> +	if (!pm_runtime_status_suspended(&client->dev))
> +		dw9768_runtime_suspend(&client->dev);
> +	pm_runtime_set_suspended(&client->dev);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id dw9768_of_table[] = {
> +	{ .compatible = "dongwoon,dw9768" },
> +	{ .compatible = "giantec,gt9769" },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, dw9768_of_table);
> +
> +static const struct dev_pm_ops dw9768_pm_ops = {
> +	SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
> +				pm_runtime_force_resume)
> +	SET_RUNTIME_PM_OPS(dw9768_runtime_suspend, dw9768_runtime_resume, NULL)
> +};
> +
> +static struct i2c_driver dw9768_i2c_driver = {
> +	.driver = {
> +		.name = DW9768_NAME,
> +		.pm = &dw9768_pm_ops,
> +		.of_match_table = dw9768_of_table,
> +	},
> +	.probe_new  = dw9768_probe,
> +	.remove = dw9768_remove,
> +};
> +module_i2c_driver(dw9768_i2c_driver);
> +
> +MODULE_AUTHOR("Dongchun Zhu <dongchun.zhu@mediatek.com>");
> +MODULE_DESCRIPTION("DW9768 VCM driver");
> +MODULE_LICENSE("GPL v2");

-- 
Kind regards,

Sakari Ailus

Re: [V7, 2/2] media: i2c: dw9768: Add DW9768 VCM driver

[Andy Shevchenko]

On Fri, Jun 05, 2020 at 06:54:12PM +0800, Dongchun Zhu wrote:
> Add a V4L2 sub-device driver for DW9768 voice coil motor, providing
> control to set the desired focus via IIC serial interface.

...

> +config VIDEO_DW9768
> +	tristate "DW9768 lens voice coil support"
> +	depends on I2C && VIDEO_V4L2

No compile test?

> +	depends on PM

This is very strange dependency for ordinary driver.

> +	select MEDIA_CONTROLLER
> +	select VIDEO_V4L2_SUBDEV_API
> +	select V4L2_FWNODE

...

> +/*
> + * DW9768 requires waiting time (delay time) of t_OPR after power-up,
> + * or in the case of PD reset taking place.
> + */
> +#define DW9768_T_OPR_US				1000
> +#define DW9768_Tvib_MS_BASE10			(64 - 1)
> +#define DW9768_AAC_MODE_DEFAULT			2

> +#define DW9768_AAC_TIME_DEFAULT			0x20

Hex? Why not decimal?

> +#define DW9768_CLOCK_PRE_SCALE_DEFAULT		1

...

> +static int dw9768_mod_reg(struct dw9768 *dw9768, u8 reg, u8 mask, u8 val)
> +{
> +	struct i2c_client *client = v4l2_get_subdevdata(&dw9768->sd);
> +	int ret;
> +
> +	ret = i2c_smbus_read_byte_data(client, reg);
> +	if (ret < 0)
> +		return ret;
> +

> +	val = ((unsigned char)ret & ~mask) | (val & mask);

This cast is weird.

> +
> +	return i2c_smbus_write_byte_data(client, reg, val);
> +}

...

> +			dev_err(&client->dev, "%s I2C failure: %d",
> +				__func__, ret);

One line?

...

> +static int dw9768_release(struct dw9768 *dw9768)
> +{
> +	struct i2c_client *client = v4l2_get_subdevdata(&dw9768->sd);
> +	u32 move_delay_us = dw9768_cal_move_delay(dw9768->aac_mode,
> +						  dw9768->clock_presc,
> +						  dw9768->aac_timing) / 100;
> +	int ret, val;
> +
> +	val = round_down(dw9768->focus->val, DW9768_MOVE_STEPS);
> +	for ( ; val >= 0; val -= DW9768_MOVE_STEPS) {
> +		ret = dw9768_set_dac(dw9768, val);
> +		if (ret) {
> +			dev_err(&client->dev, "I2C write fail: %d", ret);
> +			return ret;
> +		}
> +		usleep_range(move_delay_us, move_delay_us + 1000);
> +	}


It will look more naturally in the multiplier kind of value.

	unsigned int steps = DIV_ROUND_UP(...);

	while (steps--) {
		...(..., steps * ..._MOVE_STEPS);
		...
	}

but double check arithmetics.

> +	return 0;
> +}


Also it seems we need to have writex_poll_timeout() implementation (see
iopoll.h).

-- 
With Best Regards,
Andy Shevchenko

Re: [V7, 2/2] media: i2c: dw9768: Add DW9768 VCM driver

[Tomasz Figa]

On Fri, Jun 05, 2020 at 03:14:59PM +0300, Sakari Ailus wrote:
> Hi Dongchun,
> 
> Thank you for the update.
> 
> On Fri, Jun 05, 2020 at 06:54:12PM +0800, Dongchun Zhu wrote:
> > Add a V4L2 sub-device driver for DW9768 voice coil motor, providing
> > control to set the desired focus via IIC serial interface.
> > 
> > Signed-off-by: Dongchun Zhu <dongchun.zhu@mediatek.com>
> > ---
> >  MAINTAINERS                |   1 +
> >  drivers/media/i2c/Kconfig  |  13 ++
> >  drivers/media/i2c/Makefile |   1 +
> >  drivers/media/i2c/dw9768.c | 566 +++++++++++++++++++++++++++++++++++++++++++++
> >  4 files changed, 581 insertions(+)
> >  create mode 100644 drivers/media/i2c/dw9768.c
[snip]
> > +static int dw9768_runtime_suspend(struct device *dev)
> > +{
> > +	struct i2c_client *client = to_i2c_client(dev);
> > +	struct v4l2_subdev *sd = i2c_get_clientdata(client);
> > +	struct dw9768 *dw9768 = sd_to_dw9768(sd);
> > +
> > +	dw9768_release(dw9768);
> > +	regulator_bulk_disable(ARRAY_SIZE(dw9768_supply_names),
> > +			       dw9768->supplies);
> > +
> > +	return 0;
> > +}
> > +
> > +static int dw9768_runtime_resume(struct device *dev)
> 
> __maybe_unused for this and the suspend callback.
>

These are always used. If runtime PM is disabled, they are called
explicitly in probe and remove.

Best regards,
Tomasz

Re: [V7, 2/2] media: i2c: dw9768: Add DW9768 VCM driver

[Tomasz Figa]

Hi Andy,

On Fri, Jun 05, 2020 at 03:46:43PM +0300, Andy Shevchenko wrote:
> On Fri, Jun 05, 2020 at 06:54:12PM +0800, Dongchun Zhu wrote:
> > Add a V4L2 sub-device driver for DW9768 voice coil motor, providing
> > control to set the desired focus via IIC serial interface.
> 
> ...
> 
> > +config VIDEO_DW9768
> > +	tristate "DW9768 lens voice coil support"
> > +	depends on I2C && VIDEO_V4L2
> 
> No compile test?
> 
> > +	depends on PM
> 
> This is very strange dependency for ordinary driver.
> 
> > +	select MEDIA_CONTROLLER
> > +	select VIDEO_V4L2_SUBDEV_API
> > +	select V4L2_FWNODE
> 
> ...
> 
> > +/*
> > + * DW9768 requires waiting time (delay time) of t_OPR after power-up,
> > + * or in the case of PD reset taking place.
> > + */
> > +#define DW9768_T_OPR_US				1000
> > +#define DW9768_Tvib_MS_BASE10			(64 - 1)
> > +#define DW9768_AAC_MODE_DEFAULT			2
> 
> > +#define DW9768_AAC_TIME_DEFAULT			0x20
> 
> Hex? Why not decimal?
> 
> > +#define DW9768_CLOCK_PRE_SCALE_DEFAULT		1
> 
> ...
> 
> > +static int dw9768_mod_reg(struct dw9768 *dw9768, u8 reg, u8 mask, u8 val)
> > +{
> > +	struct i2c_client *client = v4l2_get_subdevdata(&dw9768->sd);
> > +	int ret;
> > +
> > +	ret = i2c_smbus_read_byte_data(client, reg);
> > +	if (ret < 0)
> > +		return ret;
> > +
> 
> > +	val = ((unsigned char)ret & ~mask) | (val & mask);
> 
> This cast is weird.
> 
> > +
> > +	return i2c_smbus_write_byte_data(client, reg, val);
> > +}
> 
> ...
> 
> > +			dev_err(&client->dev, "%s I2C failure: %d",
> > +				__func__, ret);
> 
> One line?
> 
> ...
> 
> > +static int dw9768_release(struct dw9768 *dw9768)
> > +{
> > +	struct i2c_client *client = v4l2_get_subdevdata(&dw9768->sd);
> > +	u32 move_delay_us = dw9768_cal_move_delay(dw9768->aac_mode,
> > +						  dw9768->clock_presc,
> > +						  dw9768->aac_timing) / 100;
> > +	int ret, val;
> > +
> > +	val = round_down(dw9768->focus->val, DW9768_MOVE_STEPS);
> > +	for ( ; val >= 0; val -= DW9768_MOVE_STEPS) {
> > +		ret = dw9768_set_dac(dw9768, val);
> > +		if (ret) {
> > +			dev_err(&client->dev, "I2C write fail: %d", ret);
> > +			return ret;
> > +		}
> > +		usleep_range(move_delay_us, move_delay_us + 1000);
> > +	}
> 
> 
> It will look more naturally in the multiplier kind of value.
> 
> 	unsigned int steps = DIV_ROUND_UP(...);
> 
> 	while (steps--) {
> 		...(..., steps * ..._MOVE_STEPS);
> 		...
> 	}
> 
> but double check arithmetics.
> 

First of all, thank for the review!

As for this particular change suggestion, I suspect this could be a
subjective thing, because for me the current code looks more naturally
and it's what the other VCM drivers do.

> > +	return 0;
> > +}
> 
> 
> Also it seems we need to have writex_poll_timeout() implementation (see
> iopoll.h).

What would it be supposed to do? readx_poll_timeout() repeats reading
the same registers and sleeping until a condition becomes true, which is
basically "polling". In this case we're not polling anything and we're
not writing the same value, but it's an explicit algorithm of this
driver to power down the VCM corectly.

However, given that it's quite common among VCMs to require this kind of
phased power down - we could indeed provide some V4L2 VCM helpers for open
and release.

Best regards,
Tomasz

Re: [V7, 2/2] media: i2c: dw9768: Add DW9768 VCM driver

[Sakari Ailus]

On Fri, Jun 05, 2020 at 01:02:12PM +0000, Tomasz Figa wrote:
> On Fri, Jun 05, 2020 at 03:14:59PM +0300, Sakari Ailus wrote:
> > Hi Dongchun,
> > 
> > Thank you for the update.
> > 
> > On Fri, Jun 05, 2020 at 06:54:12PM +0800, Dongchun Zhu wrote:
> > > Add a V4L2 sub-device driver for DW9768 voice coil motor, providing
> > > control to set the desired focus via IIC serial interface.
> > > 
> > > Signed-off-by: Dongchun Zhu <dongchun.zhu@mediatek.com>
> > > ---
> > >  MAINTAINERS                |   1 +
> > >  drivers/media/i2c/Kconfig  |  13 ++
> > >  drivers/media/i2c/Makefile |   1 +
> > >  drivers/media/i2c/dw9768.c | 566 +++++++++++++++++++++++++++++++++++++++++++++
> > >  4 files changed, 581 insertions(+)
> > >  create mode 100644 drivers/media/i2c/dw9768.c
> [snip]
> > > +static int dw9768_runtime_suspend(struct device *dev)
> > > +{
> > > +	struct i2c_client *client = to_i2c_client(dev);
> > > +	struct v4l2_subdev *sd = i2c_get_clientdata(client);
> > > +	struct dw9768 *dw9768 = sd_to_dw9768(sd);
> > > +
> > > +	dw9768_release(dw9768);
> > > +	regulator_bulk_disable(ARRAY_SIZE(dw9768_supply_names),
> > > +			       dw9768->supplies);
> > > +
> > > +	return 0;
> > > +}
> > > +
> > > +static int dw9768_runtime_resume(struct device *dev)
> > 
> > __maybe_unused for this and the suspend callback.
> >
> 
> These are always used. If runtime PM is disabled, they are called
> explicitly in probe and remove.

Ah, right. Thanks for pointing that out.

-- 
Sakari Ailus

Re: [V7, 2/2] media: i2c: dw9768: Add DW9768 VCM driver

[Tomasz Figa]

Hi Dongchun,

On Fri, Jun 05, 2020 at 06:54:12PM +0800, Dongchun Zhu wrote:
> Add a V4L2 sub-device driver for DW9768 voice coil motor, providing
> control to set the desired focus via IIC serial interface.
> 
> Signed-off-by: Dongchun Zhu <dongchun.zhu@mediatek.com>
> ---
>  MAINTAINERS                |   1 +
>  drivers/media/i2c/Kconfig  |  13 ++
>  drivers/media/i2c/Makefile |   1 +
>  drivers/media/i2c/dw9768.c | 566 +++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 581 insertions(+)
>  create mode 100644 drivers/media/i2c/dw9768.c
> 

Thank you for the patch. Please see my comments inline.

[snip]
> +/*
> + * DW9768 requires waiting time (delay time) of t_OPR after power-up,
> + * or in the case of PD reset taking place.
> + */
> +#define DW9768_T_OPR_US				1000
> +#define DW9768_Tvib_MS_BASE10			(64 - 1)

Kernel macro names are uppercase only.

[snip]
> +	/* Set AAC Timing */
> +	if (dw9768->aac_timing != DW9768_AAC_TIME_DEFAULT) {
> +		ret = i2c_smbus_write_byte_data(client, DW9768_AAC_TIME_REG,
> +						dw9768->aac_timing);
> +		if (ret < 0)
> +			return ret;
> +	}
> +
> +	move_delay_us = dw9768_cal_move_delay(dw9768->aac_mode,
> +					      dw9768->clock_presc,
> +					      dw9768->aac_timing) / 100;

We could calculate this once in probe() and store the ready us value in
the dw9768 struct.

> +
> +	for (val = dw9768->focus->val % DW9768_MOVE_STEPS;
> +	     val <= dw9768->focus->val;
> +	     val += DW9768_MOVE_STEPS) {
> +		ret = dw9768_set_dac(dw9768, val);
> +		if (ret) {
> +			dev_err(&client->dev, "%s I2C failure: %d",
> +				__func__, ret);
> +			return ret;
> +		}
> +		usleep_range(move_delay_us, move_delay_us + 1000);
> +	}
> +
> +	return 0;
> +}
[snip]
> +	pm_runtime_enable(dev);
> +	if (!pm_runtime_enabled(dev)) {
> +		ret = dw9768_runtime_resume(dev);
> +		if (ret < 0) {
> +			dev_err(dev, "failed to power on: %d\n", ret);
> +			goto err_clean_entity;
> +		}
> +	}
> +
> +	ret = v4l2_async_register_subdev(&dw9768->sd);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to register V4L2 subdev: %d", ret);
> +		goto error_async_register;
> +	}
> +
> +	return 0;
> +
> +error_async_register:

The recommendation is to name the labels after the clean-up task that needs
to be done. Should this one be called error_power_off?

> +	if (!pm_runtime_enabled(dev))
> +		dw9768_runtime_suspend(dev);

Shouldn't we also call pm_runtime_disable() here?

> +err_clean_entity:
> +	media_entity_cleanup(&dw9768->sd.entity);
> +err_free_handler:
> +	v4l2_ctrl_handler_free(&dw9768->ctrls);
> +
> +	return ret;
> +}
> +
> +static int dw9768_remove(struct i2c_client *client)
> +{
> +	struct v4l2_subdev *sd = i2c_get_clientdata(client);
> +	struct dw9768 *dw9768 = sd_to_dw9768(sd);
> +
> +	v4l2_async_unregister_subdev(&dw9768->sd);
> +	v4l2_ctrl_handler_free(&dw9768->ctrls);
> +	media_entity_cleanup(&dw9768->sd.entity);
> +	pm_runtime_disable(&client->dev);
> +	if (!pm_runtime_status_suspended(&client->dev))

pm_runtime_status_suspended() doesn't consider the runtime PM disable
state. There is also pm_runtime_suspended() and that should be correct
here.

Best regards,
Tomasz

Re: [V7, 2/2] media: i2c: dw9768: Add DW9768 VCM driver

[Dongchun Zhu]

Hi Andy,

Thanks for the review. My replies are as below.

On Fri, 2020-06-05 at 15:46 +0300, Andy Shevchenko wrote:
> On Fri, Jun 05, 2020 at 06:54:12PM +0800, Dongchun Zhu wrote:
> > Add a V4L2 sub-device driver for DW9768 voice coil motor, providing
> > control to set the desired focus via IIC serial interface.
> 
> ...
> 
> > +config VIDEO_DW9768
> > +	tristate "DW9768 lens voice coil support"
> > +	depends on I2C && VIDEO_V4L2
> 
> No compile test?
> 

Sorry?
Kconfig here is based on the current media tree master branch.
It is also what the other similar drivers from Dongwoon do. 

> > +	depends on PM
> 
> This is very strange dependency for ordinary driver.
> 

Thanks for the reminder.
This would be removed in next release.
As dw9768_runtime_resume/suspend would be called if runtime PM is
disabled.

> > +	select MEDIA_CONTROLLER
> > +	select VIDEO_V4L2_SUBDEV_API
> > +	select V4L2_FWNODE
> 
> ...
> 
> > +/*
> > + * DW9768 requires waiting time (delay time) of t_OPR after power-up,
> > + * or in the case of PD reset taking place.
> > + */
> > +#define DW9768_T_OPR_US				1000
> > +#define DW9768_Tvib_MS_BASE10			(64 - 1)
> > +#define DW9768_AAC_MODE_DEFAULT			2
> 
> > +#define DW9768_AAC_TIME_DEFAULT			0x20
> 
> Hex? Why not decimal?
> 

There is one optional property 'dongwoon,aac-timing' defined in DT.
I don't know whether you have noticed that.

'DW9768_AAC_TIME_DEFAULT' is the value set to AACT[5:0] register.
I thought the Hex unit should be proper as it is directly written to the
Hex register.

> > +#define DW9768_CLOCK_PRE_SCALE_DEFAULT		1
> 
> ...
> 
> > +static int dw9768_mod_reg(struct dw9768 *dw9768, u8 reg, u8 mask, u8 val)
> > +{
> > +	struct i2c_client *client = v4l2_get_subdevdata(&dw9768->sd);
> > +	int ret;
> > +
> > +	ret = i2c_smbus_read_byte_data(client, reg);
> > +	if (ret < 0)
> > +		return ret;
> > +
> 
> > +	val = ((unsigned char)ret & ~mask) | (val & mask);
> 
> This cast is weird.
> 

Thanks for the review, but this cast is using classical pattern from
your suggestion on OV02A10 v5:
https://patchwork.linuxtv.org/patch/59788/

So I wonder whether it is still required to be refined currently.
Or what would it be supposed to do for the cast?

> > +
> > +	return i2c_smbus_write_byte_data(client, reg, val);
> > +}
> 
> ...
> 
> > +			dev_err(&client->dev, "%s I2C failure: %d",
> > +				__func__, ret);
> 
> One line?
> 

Splitting the sentence into two lines or not should both be okay.
Of course, I could put them in one line in next release.

> ...
> 
> > +static int dw9768_release(struct dw9768 *dw9768)
> > +{
> > +	struct i2c_client *client = v4l2_get_subdevdata(&dw9768->sd);
> > +	u32 move_delay_us = dw9768_cal_move_delay(dw9768->aac_mode,
> > +						  dw9768->clock_presc,
> > +						  dw9768->aac_timing) / 100;
> > +	int ret, val;
> > +
> > +	val = round_down(dw9768->focus->val, DW9768_MOVE_STEPS);
> > +	for ( ; val >= 0; val -= DW9768_MOVE_STEPS) {
> > +		ret = dw9768_set_dac(dw9768, val);
> > +		if (ret) {
> > +			dev_err(&client->dev, "I2C write fail: %d", ret);
> > +			return ret;
> > +		}
> > +		usleep_range(move_delay_us, move_delay_us + 1000);
> > +	}
> 
> 
> It will look more naturally in the multiplier kind of value.
> 
> 	unsigned int steps = DIV_ROUND_UP(...);
> 
> 	while (steps--) {
> 		...(..., steps * ..._MOVE_STEPS);
> 		...
> 	}
> 
> but double check arithmetics.
> 

The current coding style is actually updated with reference to your
previous comments on DW9768 v3:
https://patchwork.linuxtv.org/patch/61856/

> > +	return 0;
> > +}
> 
> 
> Also it seems we need to have writex_poll_timeout() implementation (see
> iopoll.h).
> 

Re: [V7, 2/2] media: i2c: dw9768: Add DW9768 VCM driver

[Dongchun Zhu]

Hi Sakari,

Thanks for the timely review.

On Fri, 2020-06-05 at 15:14 +0300, Sakari Ailus wrote:
> Hi Dongchun,
> 
> Thank you for the update.
> 
> On Fri, Jun 05, 2020 at 06:54:12PM +0800, Dongchun Zhu wrote:
> > Add a V4L2 sub-device driver for DW9768 voice coil motor, providing
> > control to set the desired focus via IIC serial interface.
> > 
> > Signed-off-by: Dongchun Zhu <dongchun.zhu@mediatek.com>
> > ---
> >  MAINTAINERS                |   1 +
> >  drivers/media/i2c/Kconfig  |  13 ++
> >  drivers/media/i2c/Makefile |   1 +
> >  drivers/media/i2c/dw9768.c | 566 +++++++++++++++++++++++++++++++++++++++++++++
> >  4 files changed, 581 insertions(+)
> >  create mode 100644 drivers/media/i2c/dw9768.c
> > 

[snip]...

> > +
> > +static int dw9768_probe(struct i2c_client *client)
> > +{
> > +	struct device *dev = &client->dev;
> > +	struct dw9768 *dw9768;
> > +	u32 aac_mode_select;
> > +	u32 aac_timing_select;
> > +	u32 clock_presc_select;
> > +	unsigned int i;
> > +	int ret;
> > +
> > +	dw9768 = devm_kzalloc(dev, sizeof(*dw9768), GFP_KERNEL);
> > +	if (!dw9768)
> > +		return -ENOMEM;
> > +
> > +	/* Initialize subdev */
> > +	v4l2_i2c_subdev_init(&dw9768->sd, client, &dw9768_ops);
> > +
> > +	dw9768->aac_mode = DW9768_AAC_MODE_DEFAULT;
> > +	dw9768->aac_timing = DW9768_AAC_TIME_DEFAULT;
> > +	dw9768->clock_presc = DW9768_CLOCK_PRE_SCALE_DEFAULT;
> > +
> > +	/* Optional indication of AAC mode select */
> > +	ret = fwnode_property_read_u32(dev_fwnode(dev), "dongwoon,aac-mode",
> > +				       &aac_mode_select);
> > +
> > +	if (!ret)
> > +		dw9768->aac_mode = aac_mode_select;
> > +
> > +	/* Optional indication of clock pre-scale select */
> > +	ret = fwnode_property_read_u32(dev_fwnode(dev), "dongwoon,clock-presc",
> > +				       &clock_presc_select);
> > +
> > +	if (!ret)
> > +		dw9768->clock_presc = clock_presc_select;
> > +
> > +	/* Optional indication of AAC Timing */
> > +	ret = fwnode_property_read_u32(dev_fwnode(dev), "dongwoon,aac-timing",
> > +				       &aac_timing_select);
> > +
> > +	if (!ret)
> > +		dw9768->aac_timing = aac_timing_select;
> 
> You can assign the defaults to the dw9768 struct and use the fwnode
> property API to read the properties into the same fields. No return values
> need to be checked.
> 

Good idea :-)

> > +
> > +	for (i = 0; i < ARRAY_SIZE(dw9768_supply_names); i++)
> > +		dw9768->supplies[i].supply = dw9768_supply_names[i];
> > +
> > +	ret = devm_regulator_bulk_get(dev, ARRAY_SIZE(dw9768_supply_names),
> > +				      dw9768->supplies);
> > +	if (ret) {
> > +		dev_err(dev, "failed to get regulators\n");
> > +		return ret;
> > +	}
> > +
> > +	/* Initialize controls */
> > +	ret = dw9768_init_controls(dw9768);
> > +	if (ret)
> > +		goto err_free_handler;
> > +
> > +	/* Initialize subdev */
> > +	dw9768->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
> > +	dw9768->sd.internal_ops = &dw9768_int_ops;
> > +
> > +	ret = media_entity_pads_init(&dw9768->sd.entity, 0, NULL);
> > +	if (ret < 0)
> > +		goto err_free_handler;
> > +
> > +	dw9768->sd.entity.function = MEDIA_ENT_F_LENS;
> > +
> > +	pm_runtime_enable(dev);
> > +	if (!pm_runtime_enabled(dev)) {
> > +		ret = dw9768_runtime_resume(dev);
> > +		if (ret < 0) {
> > +			dev_err(dev, "failed to power on: %d\n", ret);
> > +			goto err_clean_entity;
> > +		}
> > +	}
> > +
> > +	ret = v4l2_async_register_subdev(&dw9768->sd);
> > +	if (ret < 0) {
> > +		dev_err(dev, "failed to register V4L2 subdev: %d", ret);
> > +		goto error_async_register;
> > +	}
> > +
> > +	return 0;
> > +
> > +error_async_register:
> > +	if (!pm_runtime_enabled(dev))
> > +		dw9768_runtime_suspend(dev);
> > +err_clean_entity:
> > +	media_entity_cleanup(&dw9768->sd.entity);
> > +err_free_handler:
> > +	v4l2_ctrl_handler_free(&dw9768->ctrls);
> > +
> > +	return ret;
> > +}
> > +

[snip]...

Re: [V7, 2/2] media: i2c: dw9768: Add DW9768 VCM driver

[Dongchun Zhu]

Hi Tomasz,

Thanks for the review.

On Fri, 2020-06-05 at 13:44 +0000, Tomasz Figa wrote:
> Hi Dongchun,
> 
> On Fri, Jun 05, 2020 at 06:54:12PM +0800, Dongchun Zhu wrote:
> > Add a V4L2 sub-device driver for DW9768 voice coil motor, providing
> > control to set the desired focus via IIC serial interface.
> > 
> > Signed-off-by: Dongchun Zhu <dongchun.zhu@mediatek.com>
> > ---
> >  MAINTAINERS                |   1 +
> >  drivers/media/i2c/Kconfig  |  13 ++
> >  drivers/media/i2c/Makefile |   1 +
> >  drivers/media/i2c/dw9768.c | 566 +++++++++++++++++++++++++++++++++++++++++++++
> >  4 files changed, 581 insertions(+)
> >  create mode 100644 drivers/media/i2c/dw9768.c
> > 
> 
> Thank you for the patch. Please see my comments inline.
> 
> [snip]
> > +/*
> > + * DW9768 requires waiting time (delay time) of t_OPR after power-up,
> > + * or in the case of PD reset taking place.
> > + */
> > +#define DW9768_T_OPR_US				1000
> > +#define DW9768_Tvib_MS_BASE10			(64 - 1)
> 
> Kernel macro names are uppercase only.
> 

Aha... This is caused by my carelessness.
Fixed in next release.

> [snip]
> > +	/* Set AAC Timing */
> > +	if (dw9768->aac_timing != DW9768_AAC_TIME_DEFAULT) {
> > +		ret = i2c_smbus_write_byte_data(client, DW9768_AAC_TIME_REG,
> > +						dw9768->aac_timing);
> > +		if (ret < 0)
> > +			return ret;
> > +	}
> > +
> > +	move_delay_us = dw9768_cal_move_delay(dw9768->aac_mode,
> > +					      dw9768->clock_presc,
> > +					      dw9768->aac_timing) / 100;
> 
> We could calculate this once in probe() and store the ready us value in
> the dw9768 struct.
> 

Great idea :-)
From the perspective of 'move_delay_us' itself, it defines VCM Operation
Time, which is indeed an intrinsic parameter that belongs to DW9768
private structure.

> > +
> > +	for (val = dw9768->focus->val % DW9768_MOVE_STEPS;
> > +	     val <= dw9768->focus->val;
> > +	     val += DW9768_MOVE_STEPS) {
> > +		ret = dw9768_set_dac(dw9768, val);
> > +		if (ret) {
> > +			dev_err(&client->dev, "%s I2C failure: %d",
> > +				__func__, ret);
> > +			return ret;
> > +		}
> > +		usleep_range(move_delay_us, move_delay_us + 1000);
> > +	}
> > +
> > +	return 0;
> > +}
> [snip]
> > +	pm_runtime_enable(dev);
> > +	if (!pm_runtime_enabled(dev)) {
> > +		ret = dw9768_runtime_resume(dev);
> > +		if (ret < 0) {
> > +			dev_err(dev, "failed to power on: %d\n", ret);
> > +			goto err_clean_entity;
> > +		}
> > +	}
> > +
> > +	ret = v4l2_async_register_subdev(&dw9768->sd);
> > +	if (ret < 0) {
> > +		dev_err(dev, "failed to register V4L2 subdev: %d", ret);
> > +		goto error_async_register;
> > +	}
> > +
> > +	return 0;
> > +
> > +error_async_register:
> 
> The recommendation is to name the labels after the clean-up task that needs
> to be done. Should this one be called error_power_off?
> 

Understood.
'error_async_register' would be replaced of 'err_power_off' in next
release.

> > +	if (!pm_runtime_enabled(dev))
> > +		dw9768_runtime_suspend(dev);
> 
> Shouldn't we also call pm_runtime_disable() here?
> 

Thanks for the reminder.
We would add pm_runtime_disable() in next release.
Just like:
err_power_off:
	pm_runtime_disable(dev);
	if (!pm_runtime_enabled(dev))
		dw9768_runtime_suspend(dev);

> > +err_clean_entity:
> > +	media_entity_cleanup(&dw9768->sd.entity);
> > +err_free_handler:
> > +	v4l2_ctrl_handler_free(&dw9768->ctrls);
> > +
> > +	return ret;
> > +}
> > +
> > +static int dw9768_remove(struct i2c_client *client)
> > +{
> > +	struct v4l2_subdev *sd = i2c_get_clientdata(client);
> > +	struct dw9768 *dw9768 = sd_to_dw9768(sd);
> > +
> > +	v4l2_async_unregister_subdev(&dw9768->sd);
> > +	v4l2_ctrl_handler_free(&dw9768->ctrls);
> > +	media_entity_cleanup(&dw9768->sd.entity);
> > +	pm_runtime_disable(&client->dev);
> > +	if (!pm_runtime_status_suspended(&client->dev))
> 
> pm_runtime_status_suspended() doesn't consider the runtime PM disable
> state. There is also pm_runtime_suspended() and that should be correct
> here.
> 

Fixed in next release.

> Best regards,
> Tomasz

Re: [V7, 2/2] media: i2c: dw9768: Add DW9768 VCM driver

[Andy Shevchenko]

On Sat, Jun 06, 2020 at 02:19:18PM +0800, Dongchun Zhu wrote:
> On Fri, 2020-06-05 at 15:46 +0300, Andy Shevchenko wrote:
> > On Fri, Jun 05, 2020 at 06:54:12PM +0800, Dongchun Zhu wrote:

...

> > > +	depends on I2C && VIDEO_V4L2
> > 
> > No compile test?
> > 
> 
> Sorry?
> Kconfig here is based on the current media tree master branch.
> It is also what the other similar drivers from Dongwoon do. 

COMPILE_TEST.
I dunno if it's established or not practice in media subsystem.

...

> > > +/*
> > > + * DW9768 requires waiting time (delay time) of t_OPR after power-up,
> > > + * or in the case of PD reset taking place.
> > > + */
> > > +#define DW9768_T_OPR_US				1000
> > > +#define DW9768_Tvib_MS_BASE10			(64 - 1)
> > > +#define DW9768_AAC_MODE_DEFAULT			2
> > 
> > > +#define DW9768_AAC_TIME_DEFAULT			0x20
> > 
> > Hex? Why not decimal?
> > 
> 
> There is one optional property 'dongwoon,aac-timing' defined in DT.
> I don't know whether you have noticed that.
> 
> 'DW9768_AAC_TIME_DEFAULT' is the value set to AACT[5:0] register.
> I thought the Hex unit should be proper as it is directly written to the
> Hex register.

I see. I would rather put it like (BIT(6) / 2) to show explicitly that we
choose half of the resolution.

...

> > > +	val = ((unsigned char)ret & ~mask) | (val & mask);
> > 
> > This cast is weird.
> > 
> 
> Thanks for the review, but this cast is using classical pattern from
> your suggestion on OV02A10 v5:
> https://patchwork.linuxtv.org/patch/59788/
> 
> So I wonder whether it is still required to be refined currently.
> Or what would it be supposed to do for the cast?

Okay, does it produce a warning w/o cast?
If yes, replace it at least to be the same type as mask and val.

...

> > > +	for ( ; val >= 0; val -= DW9768_MOVE_STEPS) {
> > > +		ret = dw9768_set_dac(dw9768, val);
> > > +		if (ret) {
> > > +			dev_err(&client->dev, "I2C write fail: %d", ret);
> > > +			return ret;
> > > +		}
> > > +		usleep_range(move_delay_us, move_delay_us + 1000);
> > > +	}
> > 
> > 
> > It will look more naturally in the multiplier kind of value.
> > 
> > 	unsigned int steps = DIV_ROUND_UP(...);
> > 
> > 	while (steps--) {
> > 		...(..., steps * ..._MOVE_STEPS);
> > 		...
> > 	}
> > 
> > but double check arithmetics.
> 
> The current coding style is actually updated with reference to your
> previous comments on DW9768 v3:
> https://patchwork.linuxtv.org/patch/61856/

I understand, but can you consider to go further and see if the proposal works?

-- 
With Best Regards,
Andy Shevchenko

Re: [V7, 2/2] media: i2c: dw9768: Add DW9768 VCM driver

[Dongchun Zhu]

Hi Andy,

On Mon, 2020-06-08 at 16:27 +0300, Andy Shevchenko wrote:
> On Sat, Jun 06, 2020 at 02:19:18PM +0800, Dongchun Zhu wrote:
> > On Fri, 2020-06-05 at 15:46 +0300, Andy Shevchenko wrote:
> > > On Fri, Jun 05, 2020 at 06:54:12PM +0800, Dongchun Zhu wrote:
> 
> ...
> 
> > > > +	depends on I2C && VIDEO_V4L2
> > > 
> > > No compile test?
> > > 
> > 
> > Sorry?
> > Kconfig here is based on the current media tree master branch.
> > It is also what the other similar drivers from Dongwoon do. 
> 
> COMPILE_TEST.
> I dunno if it's established or not practice in media subsystem.
> 
> ...
> 
> > > > +/*
> > > > + * DW9768 requires waiting time (delay time) of t_OPR after power-up,
> > > > + * or in the case of PD reset taking place.
> > > > + */
> > > > +#define DW9768_T_OPR_US				1000
> > > > +#define DW9768_Tvib_MS_BASE10			(64 - 1)
> > > > +#define DW9768_AAC_MODE_DEFAULT			2
> > > 
> > > > +#define DW9768_AAC_TIME_DEFAULT			0x20
> > > 
> > > Hex? Why not decimal?
> > > 
> > 
> > There is one optional property 'dongwoon,aac-timing' defined in DT.
> > I don't know whether you have noticed that.
> > 
> > 'DW9768_AAC_TIME_DEFAULT' is the value set to AACT[5:0] register.
> > I thought the Hex unit should be proper as it is directly written to the
> > Hex register.
> 
> I see. I would rather put it like (BIT(6) / 2) to show explicitly that we
> choose half of the resolution.
> 

I knew your idea.
'(BIT(6) / 2)' may somewhat show the meaning of 'median of the total
range of AACT[5:0]'.

But this value is still very obscure relative to '0x20'.
As I thought that simple is the best, especially for kernel upstream
patch.

> ...
> 
> > > > +	val = ((unsigned char)ret & ~mask) | (val & mask);
> > > 
> > > This cast is weird.
> > > 
> > 
> > Thanks for the review, but this cast is using classical pattern from
> > your suggestion on OV02A10 v5:
> > https://patchwork.linuxtv.org/patch/59788/
> > 
> > So I wonder whether it is still required to be refined currently.
> > Or what would it be supposed to do for the cast?
> 
> Okay, does it produce a warning w/o cast?
> If yes, replace it at least to be the same type as mask and val.
> 

No.

> ...
> 
> > > > +	for ( ; val >= 0; val -= DW9768_MOVE_STEPS) {
> > > > +		ret = dw9768_set_dac(dw9768, val);
> > > > +		if (ret) {
> > > > +			dev_err(&client->dev, "I2C write fail: %d", ret);
> > > > +			return ret;
> > > > +		}
> > > > +		usleep_range(move_delay_us, move_delay_us + 1000);
> > > > +	}
> > > 
> > > 
> > > It will look more naturally in the multiplier kind of value.
> > > 
> > > 	unsigned int steps = DIV_ROUND_UP(...);
> > > 
> > > 	while (steps--) {
> > > 		...(..., steps * ..._MOVE_STEPS);
> > > 		...
> > > 	}
> > > 
> > > but double check arithmetics.
> > 
> > The current coding style is actually updated with reference to your
> > previous comments on DW9768 v3:
> > https://patchwork.linuxtv.org/patch/61856/
> 
> I understand, but can you consider to go further and see if the proposal works?
> 

In fact, your suggestion is something like one another method to set DAC
value to actuator.
It is like there may be several solutions to a question.

Yes. I just tried the new method and it works as expected.
u32 steps = DIV_ROUND_UP(dw9768->focus->val, DW9768_MOVE_STEPS);
while (steps--) {
	ret = dw9768_set_dac(dw9768, steps * DW9768_MOVE_STEPS);
	if (ret)
		return ret;
	usleep_range(move_delay_us, move_delay_us + 1000);
}

But from my perspective, I may prefer to the original method.
As here what we really care is the DAC value,
'dw9768_set_dac(dw9768, val)' seems more simple.

Re: [V7, 2/2] media: i2c: dw9768: Add DW9768 VCM driver

[Andy Shevchenko]

On Tue, Jun 09, 2020 at 11:45:41AM +0800, Dongchun Zhu wrote:
> On Mon, 2020-06-08 at 16:27 +0300, Andy Shevchenko wrote:
> > On Sat, Jun 06, 2020 at 02:19:18PM +0800, Dongchun Zhu wrote:
> > > On Fri, 2020-06-05 at 15:46 +0300, Andy Shevchenko wrote:
> > > > On Fri, Jun 05, 2020 at 06:54:12PM +0800, Dongchun Zhu wrote:

...

> > > > > +#define DW9768_AAC_TIME_DEFAULT			0x20
> > > > 
> > > > Hex? Why not decimal?
> > > > 
> > > 
> > > There is one optional property 'dongwoon,aac-timing' defined in DT.
> > > I don't know whether you have noticed that.
> > > 
> > > 'DW9768_AAC_TIME_DEFAULT' is the value set to AACT[5:0] register.
> > > I thought the Hex unit should be proper as it is directly written to the
> > > Hex register.
> > 
> > I see. I would rather put it like (BIT(6) / 2) to show explicitly that we
> > choose half of the resolution.
> > 
> 
> I knew your idea.
> '(BIT(6) / 2)' may somewhat show the meaning of 'median of the total
> range of AACT[5:0]'.
> 
> But this value is still very obscure relative to '0x20'.
> As I thought that simple is the best, especially for kernel upstream
> patch.

Okay, let's wait for maintainers to speak up.

...

> > > > > +	for ( ; val >= 0; val -= DW9768_MOVE_STEPS) {
> > > > > +		ret = dw9768_set_dac(dw9768, val);
> > > > > +		if (ret) {
> > > > > +			dev_err(&client->dev, "I2C write fail: %d", ret);
> > > > > +			return ret;
> > > > > +		}
> > > > > +		usleep_range(move_delay_us, move_delay_us + 1000);
> > > > > +	}
> > > > 
> > > > 
> > > > It will look more naturally in the multiplier kind of value.
> > > > 
> > > > 	unsigned int steps = DIV_ROUND_UP(...);
> > > > 
> > > > 	while (steps--) {
> > > > 		...(..., steps * ..._MOVE_STEPS);
> > > > 		...
> > > > 	}
> > > > 
> > > > but double check arithmetics.
> > > 
> > > The current coding style is actually updated with reference to your
> > > previous comments on DW9768 v3:
> > > https://patchwork.linuxtv.org/patch/61856/
> > 
> > I understand, but can you consider to go further and see if the proposal works?
> > 
> 
> In fact, your suggestion is something like one another method to set DAC
> value to actuator.
> It is like there may be several solutions to a question.
> 
> Yes. I just tried the new method and it works as expected.
> u32 steps = DIV_ROUND_UP(dw9768->focus->val, DW9768_MOVE_STEPS);
> while (steps--) {
> 	ret = dw9768_set_dac(dw9768, steps * DW9768_MOVE_STEPS);
> 	if (ret)
> 		return ret;
> 	usleep_range(move_delay_us, move_delay_us + 1000);
> }
> 
> But from my perspective, I may prefer to the original method.
> As here what we really care is the DAC value,
> 'dw9768_set_dac(dw9768, val)' seems more simple.

OK.


-- 
With Best Regards,
Andy Shevchenko

Re: [V7, 1/2] media: dt-bindings: media: i2c: Document DW9768 bindings

[Rob Herring]

On Fri, 05 Jun 2020 18:54:11 +0800, Dongchun Zhu wrote:
> Add DeviceTree binding documentation for Dongwoon Anatech DW9768 voice
> coil actuator.
> 
> Signed-off-by: Dongchun Zhu <dongchun.zhu@mediatek.com>
> ---
>  .../bindings/media/i2c/dongwoon,dw9768.yaml        | 100 +++++++++++++++++++++
>  MAINTAINERS                                        |   7 ++
>  2 files changed, 107 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/media/i2c/dongwoon,dw9768.yaml
> 

Reviewed-by: Rob Herring <robh@kernel.org>

Re: [V7, 2/2] media: i2c: dw9768: Add DW9768 VCM driver

[Sakari Ailus]

Hi Andy, Dongchun,

On Tue, Jun 09, 2020 at 02:14:28PM +0300, Andy Shevchenko wrote:
> On Tue, Jun 09, 2020 at 11:45:41AM +0800, Dongchun Zhu wrote:
> > On Mon, 2020-06-08 at 16:27 +0300, Andy Shevchenko wrote:
> > > On Sat, Jun 06, 2020 at 02:19:18PM +0800, Dongchun Zhu wrote:
> > > > On Fri, 2020-06-05 at 15:46 +0300, Andy Shevchenko wrote:
> > > > > On Fri, Jun 05, 2020 at 06:54:12PM +0800, Dongchun Zhu wrote:
> 
> ...
> 
> > > > > > +#define DW9768_AAC_TIME_DEFAULT			0x20
> > > > > 
> > > > > Hex? Why not decimal?
> > > > > 
> > > > 
> > > > There is one optional property 'dongwoon,aac-timing' defined in DT.
> > > > I don't know whether you have noticed that.
> > > > 
> > > > 'DW9768_AAC_TIME_DEFAULT' is the value set to AACT[5:0] register.
> > > > I thought the Hex unit should be proper as it is directly written to the
> > > > Hex register.
> > > 
> > > I see. I would rather put it like (BIT(6) / 2) to show explicitly that we
> > > choose half of the resolution.
> > > 
> > 
> > I knew your idea.
> > '(BIT(6) / 2)' may somewhat show the meaning of 'median of the total
> > range of AACT[5:0]'.
> > 
> > But this value is still very obscure relative to '0x20'.
> > As I thought that simple is the best, especially for kernel upstream
> > patch.
> 
> Okay, let's wait for maintainers to speak up.

The value 0x20 is the device default, I don't see it having any other
special significance. So I'm totally fine with 0x20.

-- 
Kind regards,

Sakari Ailus