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Date:   Wed, 8 Apr 2020 19:52:52 +0200
From:   Sam Ravnborg <sam@ravnborg.org>
To:     Guido =?iso-8859-1?Q?G=FCnther?= <agx@sigxcpu.org>
Cc:     David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
        Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Shawn Guo <shawnguo@kernel.org>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        Pengutronix Kernel Team <kernel@pengutronix.de>,
        Fabio Estevam <festevam@gmail.com>,
        NXP Linux Team <linux-imx@nxp.com>,
        Andrzej Hajda <a.hajda@samsung.com>,
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        Jonas Karlman <jonas@kwiboo.se>,
        Jernej Skrabec <jernej.skrabec@siol.net>,
        Lee Jones <lee.jones@linaro.org>,
        dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Robert Chiras <robert.chiras@nxp.com>,
        Arnd Bergmann <arnd@arndb.de>
Subject: Re: [PATCH v10 2/2] drm/bridge: Add NWL MIPI DSI host controller
 support
Message-ID: <20200408175252.GB24828@ravnborg.org>
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Hi Guido.

On Fri, Mar 20, 2020 at 07:49:10PM +0100, Guido Günther wrote:
> This adds initial support for the NWL MIPI DSI Host controller found on
> i.MX8 SoCs.
> 
> It adds support for the i.MX8MQ but the same IP can be found on
> e.g. the i.MX8QXP.
> 
> It has been tested on the Librem 5 devkit using mxsfb.
> 
> Signed-off-by: Guido Günther <agx@sigxcpu.org>
> Co-developed-by: Robert Chiras <robert.chiras@nxp.com>
> Signed-off-by: Robert Chiras <robert.chiras@nxp.com>
> Tested-by: Robert Chiras <robert.chiras@nxp.com>
> Tested-by: Martin Kepplinger <martin.kepplinger@puri.sm>

I took an extra look at the driver (procastinating).
checkpatch (--strict):
-:511: CHECK:OPEN_ENDED_LINE: Lines should not end with a '('
#511: FILE: drivers/gpu/drm/bridge/nwl-dsi.c:442:
+			DRM_DEV_ERROR(

-:671: CHECK:COMPARISON_TO_NULL: Comparison to NULL could be written "msg->rx_buf"
#671: FILE: drivers/gpu/drm/bridge/nwl-dsi.c:602:
+	    msg->rx_len > 0 && msg->rx_buf != NULL)

-:868: CHECK:OPEN_ENDED_LINE: Lines should not end with a '('
#868: FILE: drivers/gpu/drm/bridge/nwl-dsi.c:799:
+	ret = phy_mipi_dphy_get_default_config(

-:1021: WARNING:RETURN_VOID: void function return statements are not generally useful
#1021: FILE: drivers/gpu/drm/bridge/nwl-dsi.c:952:
+	return;
+}

-:1067: CHECK:LINE_SPACING: Please don't use multiple blank lines
#1067: FILE: drivers/gpu/drm/bridge/nwl-dsi.c:998:
+
+

A few more details below.

	Sam


> ---
>  drivers/gpu/drm/bridge/Kconfig   |   16 +
>  drivers/gpu/drm/bridge/Makefile  |    1 +
>  drivers/gpu/drm/bridge/nwl-dsi.c | 1218 ++++++++++++++++++++++++++++++
>  drivers/gpu/drm/bridge/nwl-dsi.h |  144 ++++
>  4 files changed, 1379 insertions(+)
>  create mode 100644 drivers/gpu/drm/bridge/nwl-dsi.c
>  create mode 100644 drivers/gpu/drm/bridge/nwl-dsi.h
> 
> diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
> index aaed2347ace9..6ec945f837b8 100644
> --- a/drivers/gpu/drm/bridge/Kconfig
> +++ b/drivers/gpu/drm/bridge/Kconfig
> @@ -58,6 +58,22 @@ config DRM_MEGACHIPS_STDPXXXX_GE_B850V3_FW
>  	  to DP++. This is used with the i.MX6 imx-ldb
>  	  driver. You are likely to say N here.
>  
> +config DRM_NWL_MIPI_DSI
> +	tristate "Northwest Logic MIPI DSI Host controller"
> +	depends on DRM
> +	depends on COMMON_CLK
> +	depends on OF && HAS_IOMEM
> +	select DRM_KMS_HELPER
> +	select DRM_MIPI_DSI
> +	select DRM_PANEL_BRIDGE
> +	select GENERIC_PHY_MIPI_DPHY
> +	select MFD_SYSCON
> +	select MULTIPLEXER
> +	select REGMAP_MMIO
> +	help
> +	  This enables the Northwest Logic MIPI DSI Host controller as
> +	  for example found on NXP's i.MX8 Processors.
> +
>  config DRM_NXP_PTN3460
>  	tristate "NXP PTN3460 DP/LVDS bridge"
>  	depends on OF
> diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
> index 6fb062b5b0f0..b04ac2dfa22c 100644
> --- a/drivers/gpu/drm/bridge/Makefile
> +++ b/drivers/gpu/drm/bridge/Makefile
> @@ -18,6 +18,7 @@ obj-$(CONFIG_DRM_I2C_ADV7511) += adv7511/
>  obj-$(CONFIG_DRM_TI_SN65DSI86) += ti-sn65dsi86.o
>  obj-$(CONFIG_DRM_TI_TFP410) += ti-tfp410.o
>  obj-$(CONFIG_DRM_TI_TPD12S015) += ti-tpd12s015.o
> +obj-$(CONFIG_DRM_NWL_MIPI_DSI) += nwl-dsi.o
>  
>  obj-y += analogix/
>  obj-y += synopsys/
> diff --git a/drivers/gpu/drm/bridge/nwl-dsi.c b/drivers/gpu/drm/bridge/nwl-dsi.c
> new file mode 100644
> index 000000000000..12d1c5548e2d
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/nwl-dsi.c
> @@ -0,0 +1,1218 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * i.MX8 NWL MIPI DSI host driver
> + *
> + * Copyright (C) 2017 NXP
> + * Copyright (C) 2020 Purism SPC
> + */
> +
> +#include <linux/bitfield.h>
> +#include <linux/clk.h>
> +#include <linux/irq.h>
> +#include <linux/math64.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/module.h>
> +#include <linux/mux/consumer.h>
> +#include <linux/of.h>
> +#include <linux/of_platform.h>
> +#include <linux/phy/phy.h>
> +#include <linux/regmap.h>
> +#include <linux/reset.h>
> +#include <linux/sys_soc.h>
> +#include <linux/time64.h>
> +
> +#include <drm/drm_atomic_helper.h>
Header file is not used - drop

> +#include <drm/drm_bridge.h>
> +#include <drm/drm_mipi_dsi.h>
> +#include <drm/drm_of.h>
> +#include <drm/drm_panel.h>
> +#include <drm/drm_print.h>

> +#include <drm/drm_probe_helper.h>
Header file is not used - drop
> +
> +#include <video/mipi_display.h>

> +#include <video/videomode.h>
Header file not used

> +
> +#include "nwl-dsi.h"
> +
> +#define DRV_NAME "nwl-dsi"
> +
> +/* i.MX8 NWL quirks */
> +/* i.MX8MQ errata E11418 */
> +#define E11418_HS_MODE_QUIRK	BIT(0)
> +
> +#define NWL_DSI_MIPI_FIFO_TIMEOUT msecs_to_jiffies(500)
Should the defines be moved to the header file?

> +
> +enum transfer_direction {
> +	DSI_PACKET_SEND,
> +	DSI_PACKET_RECEIVE,
> +};
> +
> +#define NWL_DSI_ENDPOINT_LCDIF 0
> +#define NWL_DSI_ENDPOINT_DCSS 1
> +
> +struct nwl_dsi_plat_clk_config {
> +	const char *id;
> +	struct clk *clk;
> +	bool present;
> +};
> +
> +struct nwl_dsi_transfer {
> +	const struct mipi_dsi_msg *msg;
> +	struct mipi_dsi_packet packet;
> +	struct completion completed;
> +
> +	int status; /* status of transmission */
> +	enum transfer_direction direction;
> +	bool need_bta;
> +	u8 cmd;
> +	u16 rx_word_count;
> +	size_t tx_len; /* in bytes */
> +	size_t rx_len; /* in bytes */
> +};
> +
> +struct nwl_dsi {
> +	struct drm_bridge bridge;
> +	struct mipi_dsi_host dsi_host;
> +	struct drm_bridge *panel_bridge;
> +	struct device *dev;
> +	struct phy *phy;
> +	union phy_configure_opts phy_cfg;
> +	unsigned int quirks;
> +
> +	struct regmap *regmap;
> +	int irq;
> +	/*
> +	 * The DSI host controller needs this reset sequence according to NWL:
> +	 * 1. Deassert pclk reset to get access to DSI regs
> +	 * 2. Configure DSI Host and DPHY and enable DPHY
> +	 * 3. Deassert ESC and BYTE resets to allow host TX operations)
> +	 * 4. Send DSI cmds to configure peripheral (handled by panel drv)
> +	 * 5. Deassert DPI reset so DPI receives pixels and starts sending
> +	 *    DSI data
> +	 *
> +	 * TODO: Since panel_bridges do their DSI setup in enable we
> +	 * currently have 4. and 5. swapped.
> +	 */
> +	struct reset_control *rst_byte;
> +	struct reset_control *rst_esc;
> +	struct reset_control *rst_dpi;
> +	struct reset_control *rst_pclk;
> +	struct mux_control *mux;
> +
> +	/* DSI clocks */
> +	struct clk *phy_ref_clk;
> +	struct clk *rx_esc_clk;
> +	struct clk *tx_esc_clk;
> +	struct clk *core_clk;
> +	/*
> +	 * hardware bug: the i.MX8MQ needs this clock on during reset
> +	 * even when not using LCDIF.
> +	 */
> +	struct clk *lcdif_clk;
> +
> +	/* dsi lanes */
> +	u32 lanes;
> +	enum mipi_dsi_pixel_format format;
> +	struct drm_display_mode mode;
> +	unsigned long dsi_mode_flags;
> +	int error;
> +
> +	struct nwl_dsi_transfer *xfer;
> +};
> +
> +static const struct regmap_config nwl_dsi_regmap_config = {
> +	.reg_bits = 16,
> +	.val_bits = 32,
> +	.reg_stride = 4,
> +	.max_register = NWL_DSI_IRQ_MASK2,
> +	.name = DRV_NAME,
> +};
> +
> +static inline struct nwl_dsi *bridge_to_dsi(struct drm_bridge *bridge)
> +{
> +	return container_of(bridge, struct nwl_dsi, bridge);
> +}
> +
> +static int nwl_dsi_clear_error(struct nwl_dsi *dsi)
> +{
> +	int ret = dsi->error;
> +
> +	dsi->error = 0;
> +	return ret;
> +}
> +
> +static void nwl_dsi_write(struct nwl_dsi *dsi, unsigned int reg, u32 val)
> +{
> +	int ret;
> +
> +	if (dsi->error)
> +		return;
> +
> +	ret = regmap_write(dsi->regmap, reg, val);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(dsi->dev,
> +			      "Failed to write NWL DSI reg 0x%x: %d\n", reg,
> +			      ret);
> +		dsi->error = ret;
> +	}
> +}
> +
> +static u32 nwl_dsi_read(struct nwl_dsi *dsi, u32 reg)
> +{
> +	unsigned int val;
> +	int ret;
> +
> +	if (dsi->error)
> +		return 0;
> +
> +	ret = regmap_read(dsi->regmap, reg, &val);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(dsi->dev, "Failed to read NWL DSI reg 0x%x: %d\n",
> +			      reg, ret);
> +		dsi->error = ret;
> +	}
> +	return val;
> +}
> +
> +static int nwl_dsi_get_dpi_pixel_format(enum mipi_dsi_pixel_format format)
> +{
> +	switch (format) {
> +	case MIPI_DSI_FMT_RGB565:
> +		return NWL_DSI_PIXEL_FORMAT_16;
> +	case MIPI_DSI_FMT_RGB666:
> +		return NWL_DSI_PIXEL_FORMAT_18L;
> +	case MIPI_DSI_FMT_RGB666_PACKED:
> +		return NWL_DSI_PIXEL_FORMAT_18;
> +	case MIPI_DSI_FMT_RGB888:
> +		return NWL_DSI_PIXEL_FORMAT_24;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +/*
> + * ps2bc - Picoseconds to byte clock cycles
> + */
> +static u32 ps2bc(struct nwl_dsi *dsi, unsigned long long ps)
> +{
> +	u32 bpp = mipi_dsi_pixel_format_to_bpp(dsi->format);
> +
> +	return DIV64_U64_ROUND_UP(ps * dsi->mode.clock * bpp,
> +				  dsi->lanes * 8 * NSEC_PER_SEC);
> +}
> +
> +/*
> + * ui2bc - UI time periods to byte clock cycles
> + */
> +static u32 ui2bc(struct nwl_dsi *dsi, unsigned long long ui)
> +{
> +	u32 bpp = mipi_dsi_pixel_format_to_bpp(dsi->format);
> +
> +	return DIV64_U64_ROUND_UP(ui * dsi->lanes,
> +				  dsi->mode.clock * 1000 * bpp);
> +}
> +
> +/*
> + * us2bc - micro seconds to lp clock cycles
> + */
> +static u32 us2lp(u32 lp_clk_rate, unsigned long us)
> +{
> +	return DIV_ROUND_UP(us * lp_clk_rate, USEC_PER_SEC);
> +}
> +
> +static int nwl_dsi_config_host(struct nwl_dsi *dsi)
> +{
> +	u32 cycles;
> +	struct phy_configure_opts_mipi_dphy *cfg = &dsi->phy_cfg.mipi_dphy;
> +
> +	if (dsi->lanes < 1 || dsi->lanes > 4)
> +		return -EINVAL;
> +
> +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "DSI Lanes %d\n", dsi->lanes);
> +	nwl_dsi_write(dsi, NWL_DSI_CFG_NUM_LANES, dsi->lanes - 1);
> +
> +	if (dsi->dsi_mode_flags & MIPI_DSI_CLOCK_NON_CONTINUOUS) {
> +		nwl_dsi_write(dsi, NWL_DSI_CFG_NONCONTINUOUS_CLK, 0x01);
> +		nwl_dsi_write(dsi, NWL_DSI_CFG_AUTOINSERT_EOTP, 0x01);
> +	} else {
> +		nwl_dsi_write(dsi, NWL_DSI_CFG_NONCONTINUOUS_CLK, 0x00);
> +		nwl_dsi_write(dsi, NWL_DSI_CFG_AUTOINSERT_EOTP, 0x00);
> +	}
> +
> +	/* values in byte clock cycles */
> +	cycles = ui2bc(dsi, cfg->clk_pre);
> +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "cfg_t_pre: 0x%x\n", cycles);
> +	nwl_dsi_write(dsi, NWL_DSI_CFG_T_PRE, cycles);
> +	cycles = ps2bc(dsi, cfg->lpx + cfg->clk_prepare + cfg->clk_zero);
> +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "cfg_tx_gap (pre): 0x%x\n", cycles);
> +	cycles += ui2bc(dsi, cfg->clk_pre);
> +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "cfg_t_post: 0x%x\n", cycles);
> +	nwl_dsi_write(dsi, NWL_DSI_CFG_T_POST, cycles);
> +	cycles = ps2bc(dsi, cfg->hs_exit);
> +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "cfg_tx_gap: 0x%x\n", cycles);
> +	nwl_dsi_write(dsi, NWL_DSI_CFG_TX_GAP, cycles);
> +
> +	nwl_dsi_write(dsi, NWL_DSI_CFG_EXTRA_CMDS_AFTER_EOTP, 0x01);
> +	nwl_dsi_write(dsi, NWL_DSI_CFG_HTX_TO_COUNT, 0x00);
> +	nwl_dsi_write(dsi, NWL_DSI_CFG_LRX_H_TO_COUNT, 0x00);
> +	nwl_dsi_write(dsi, NWL_DSI_CFG_BTA_H_TO_COUNT, 0x00);
> +	/* In LP clock cycles */
> +	cycles = us2lp(cfg->lp_clk_rate, cfg->wakeup);
> +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "cfg_twakeup: 0x%x\n", cycles);
> +	nwl_dsi_write(dsi, NWL_DSI_CFG_TWAKEUP, cycles);
> +
> +	return nwl_dsi_clear_error(dsi);
> +}
> +
> +static int nwl_dsi_config_dpi(struct nwl_dsi *dsi)
> +{
> +	u32 mode;
> +	int color_format;
> +	bool burst_mode;
> +	int hfront_porch, hback_porch, vfront_porch, vback_porch;
> +	int hsync_len, vsync_len;
> +
> +	hfront_porch = dsi->mode.hsync_start - dsi->mode.hdisplay;
> +	hsync_len = dsi->mode.hsync_end - dsi->mode.hsync_start;
> +	hback_porch = dsi->mode.htotal - dsi->mode.hsync_end;
> +
> +	vfront_porch = dsi->mode.vsync_start - dsi->mode.vdisplay;
> +	vsync_len = dsi->mode.vsync_end - dsi->mode.vsync_start;
> +	vback_porch = dsi->mode.vtotal - dsi->mode.vsync_end;
> +
> +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "hfront_porch = %d\n", hfront_porch);
> +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "hback_porch = %d\n", hback_porch);
> +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "hsync_len = %d\n", hsync_len);
> +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "hdisplay = %d\n", dsi->mode.hdisplay);
> +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "vfront_porch = %d\n", vfront_porch);
> +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "vback_porch = %d\n", vback_porch);
> +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "vsync_len = %d\n", vsync_len);
> +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "vactive = %d\n", dsi->mode.vdisplay);
> +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "clock = %d kHz\n", dsi->mode.clock);
> +
> +	color_format = nwl_dsi_get_dpi_pixel_format(dsi->format);
> +	if (color_format < 0) {
> +		DRM_DEV_ERROR(dsi->dev, "Invalid color format 0x%x\n",
> +			      dsi->format);
> +		return color_format;
> +	}
> +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "pixel fmt = %d\n", dsi->format);
> +
> +	nwl_dsi_write(dsi, NWL_DSI_INTERFACE_COLOR_CODING, NWL_DSI_DPI_24_BIT);
> +	nwl_dsi_write(dsi, NWL_DSI_PIXEL_FORMAT, color_format);
> +	/*
> +	 * Adjusting input polarity based on the video mode results in
> +	 * a black screen so always pick active low:
> +	 */
> +	nwl_dsi_write(dsi, NWL_DSI_VSYNC_POLARITY,
> +		      NWL_DSI_VSYNC_POLARITY_ACTIVE_LOW);
> +	nwl_dsi_write(dsi, NWL_DSI_HSYNC_POLARITY,
> +		      NWL_DSI_HSYNC_POLARITY_ACTIVE_LOW);
> +
> +	burst_mode = (dsi->dsi_mode_flags & MIPI_DSI_MODE_VIDEO_BURST) &&
> +		     !(dsi->dsi_mode_flags & MIPI_DSI_MODE_VIDEO_SYNC_PULSE);
> +
> +	if (burst_mode) {
> +		nwl_dsi_write(dsi, NWL_DSI_VIDEO_MODE, NWL_DSI_VM_BURST_MODE);
> +		nwl_dsi_write(dsi, NWL_DSI_PIXEL_FIFO_SEND_LEVEL, 256);
> +	} else {
> +		mode = ((dsi->dsi_mode_flags & MIPI_DSI_MODE_VIDEO_SYNC_PULSE) ?
> +				NWL_DSI_VM_BURST_MODE_WITH_SYNC_PULSES :
> +				NWL_DSI_VM_NON_BURST_MODE_WITH_SYNC_EVENTS);
> +		nwl_dsi_write(dsi, NWL_DSI_VIDEO_MODE, mode);
> +		nwl_dsi_write(dsi, NWL_DSI_PIXEL_FIFO_SEND_LEVEL,
> +			      dsi->mode.hdisplay);
> +	}
> +
> +	nwl_dsi_write(dsi, NWL_DSI_HFP, hfront_porch);
> +	nwl_dsi_write(dsi, NWL_DSI_HBP, hback_porch);
> +	nwl_dsi_write(dsi, NWL_DSI_HSA, hsync_len);
> +
> +	nwl_dsi_write(dsi, NWL_DSI_ENABLE_MULT_PKTS, 0x0);
> +	nwl_dsi_write(dsi, NWL_DSI_BLLP_MODE, 0x1);
> +	nwl_dsi_write(dsi, NWL_DSI_USE_NULL_PKT_BLLP, 0x0);
> +	nwl_dsi_write(dsi, NWL_DSI_VC, 0x0);
> +
> +	nwl_dsi_write(dsi, NWL_DSI_PIXEL_PAYLOAD_SIZE, dsi->mode.hdisplay);
> +	nwl_dsi_write(dsi, NWL_DSI_VACTIVE, dsi->mode.vdisplay - 1);
> +	nwl_dsi_write(dsi, NWL_DSI_VBP, vback_porch);
> +	nwl_dsi_write(dsi, NWL_DSI_VFP, vfront_porch);
> +
> +	return nwl_dsi_clear_error(dsi);
> +}
> +
> +static int nwl_dsi_init_interrupts(struct nwl_dsi *dsi)
> +{
> +	u32 irq_enable;
> +
> +	nwl_dsi_write(dsi, NWL_DSI_IRQ_MASK, 0xffffffff);
> +	nwl_dsi_write(dsi, NWL_DSI_IRQ_MASK2, 0x7);
> +
> +	irq_enable = ~(u32)(NWL_DSI_TX_PKT_DONE_MASK |
> +			    NWL_DSI_RX_PKT_HDR_RCVD_MASK |
> +			    NWL_DSI_TX_FIFO_OVFLW_MASK |
> +			    NWL_DSI_HS_TX_TIMEOUT_MASK);
> +
> +	nwl_dsi_write(dsi, NWL_DSI_IRQ_MASK, irq_enable);
> +
> +	return nwl_dsi_clear_error(dsi);
> +}
> +
> +static int nwl_dsi_host_attach(struct mipi_dsi_host *dsi_host,
> +			       struct mipi_dsi_device *device)
> +{
> +	struct nwl_dsi *dsi = container_of(dsi_host, struct nwl_dsi, dsi_host);
> +	struct device *dev = dsi->dev;
> +
> +	DRM_DEV_INFO(dev, "lanes=%u, format=0x%x flags=0x%lx\n", device->lanes,
> +		     device->format, device->mode_flags);
> +
> +	if (device->lanes < 1 || device->lanes > 4)
> +		return -EINVAL;
> +
> +	dsi->lanes = device->lanes;
> +	dsi->format = device->format;
> +	dsi->dsi_mode_flags = device->mode_flags;
> +
> +	return 0;
> +}
> +
> +static bool nwl_dsi_read_packet(struct nwl_dsi *dsi, u32 status)
> +{
> +	struct device *dev = dsi->dev;
> +	struct nwl_dsi_transfer *xfer = dsi->xfer;
> +	int err;
> +	u8 *payload = xfer->msg->rx_buf;
> +	u32 val;
> +	u16 word_count;
> +	u8 channel;
> +	u8 data_type;
> +
> +	xfer->status = 0;
> +
> +	if (xfer->rx_word_count == 0) {
> +		if (!(status & NWL_DSI_RX_PKT_HDR_RCVD))
> +			return false;
> +		/* Get the RX header and parse it */
> +		val = nwl_dsi_read(dsi, NWL_DSI_RX_PKT_HEADER);
> +		err = nwl_dsi_clear_error(dsi);
> +		if (err)
> +			xfer->status = err;
> +		word_count = NWL_DSI_WC(val);
> +		channel = NWL_DSI_RX_VC(val);
> +		data_type = NWL_DSI_RX_DT(val);
> +
> +		if (channel != xfer->msg->channel) {
> +			DRM_DEV_ERROR(dev,
> +				      "[%02X] Channel mismatch (%u != %u)\n",
> +				      xfer->cmd, channel, xfer->msg->channel);
> +			xfer->status = -EINVAL;
> +			return true;
> +		}
> +
> +		switch (data_type) {
> +		case MIPI_DSI_RX_GENERIC_SHORT_READ_RESPONSE_2BYTE:
> +			fallthrough;
> +		case MIPI_DSI_RX_DCS_SHORT_READ_RESPONSE_2BYTE:
> +			if (xfer->msg->rx_len > 1) {
> +				/* read second byte */
> +				payload[1] = word_count >> 8;
> +				++xfer->rx_len;
> +			}
> +			fallthrough;
> +		case MIPI_DSI_RX_GENERIC_SHORT_READ_RESPONSE_1BYTE:
> +			fallthrough;
> +		case MIPI_DSI_RX_DCS_SHORT_READ_RESPONSE_1BYTE:
> +			if (xfer->msg->rx_len > 0) {
> +				/* read first byte */
> +				payload[0] = word_count & 0xff;
> +				++xfer->rx_len;
> +			}
> +			xfer->status = xfer->rx_len;
> +			return true;
> +		case MIPI_DSI_RX_ACKNOWLEDGE_AND_ERROR_REPORT:
> +			word_count &= 0xff;
> +			DRM_DEV_ERROR(dev, "[%02X] DSI error report: 0x%02x\n",
> +				      xfer->cmd, word_count);
> +			xfer->status = -EPROTO;
> +			return true;
> +		}
> +
> +		if (word_count > xfer->msg->rx_len) {
> +			DRM_DEV_ERROR(
> +				dev,
> +				"[%02X] Receive buffer too small: %zu (< %u)\n",
> +				xfer->cmd, xfer->msg->rx_len, word_count);
> +			xfer->status = -EINVAL;
> +			return true;
> +		}
> +
> +		xfer->rx_word_count = word_count;
> +	} else {
> +		/* Set word_count from previous header read */
> +		word_count = xfer->rx_word_count;
> +	}
> +
> +	/* If RX payload is not yet received, wait for it */
> +	if (!(status & NWL_DSI_RX_PKT_PAYLOAD_DATA_RCVD))
> +		return false;
> +
> +	/* Read the RX payload */
> +	while (word_count >= 4) {
> +		val = nwl_dsi_read(dsi, NWL_DSI_RX_PAYLOAD);
> +		payload[0] = (val >> 0) & 0xff;
> +		payload[1] = (val >> 8) & 0xff;
> +		payload[2] = (val >> 16) & 0xff;
> +		payload[3] = (val >> 24) & 0xff;
> +		payload += 4;
> +		xfer->rx_len += 4;
> +		word_count -= 4;
> +	}
> +
> +	if (word_count > 0) {
> +		val = nwl_dsi_read(dsi, NWL_DSI_RX_PAYLOAD);
> +		switch (word_count) {
> +		case 3:
> +			payload[2] = (val >> 16) & 0xff;
> +			++xfer->rx_len;
> +			fallthrough;
> +		case 2:
> +			payload[1] = (val >> 8) & 0xff;
> +			++xfer->rx_len;
> +			fallthrough;
> +		case 1:
> +			payload[0] = (val >> 0) & 0xff;
> +			++xfer->rx_len;
> +			break;
> +		}
> +	}
> +
> +	xfer->status = xfer->rx_len;
> +	err = nwl_dsi_clear_error(dsi);
> +	if (err)
> +		xfer->status = err;
> +
> +	return true;
> +}
> +
> +static void nwl_dsi_finish_transmission(struct nwl_dsi *dsi, u32 status)
> +{
> +	struct nwl_dsi_transfer *xfer = dsi->xfer;
> +	bool end_packet = false;
> +
> +	if (!xfer)
> +		return;
> +
> +	if (xfer->direction == DSI_PACKET_SEND &&
> +	    status & NWL_DSI_TX_PKT_DONE) {
> +		xfer->status = xfer->tx_len;
> +		end_packet = true;
> +	} else if (status & NWL_DSI_DPHY_DIRECTION &&
> +		   ((status & (NWL_DSI_RX_PKT_HDR_RCVD |
> +			       NWL_DSI_RX_PKT_PAYLOAD_DATA_RCVD)))) {
> +		end_packet = nwl_dsi_read_packet(dsi, status);
> +	}
> +
> +	if (end_packet)
> +		complete(&xfer->completed);
> +}
> +
> +static void nwl_dsi_begin_transmission(struct nwl_dsi *dsi)
> +{
> +	struct nwl_dsi_transfer *xfer = dsi->xfer;
> +	struct mipi_dsi_packet *pkt = &xfer->packet;
> +	const u8 *payload;
> +	size_t length;
> +	u16 word_count;
> +	u8 hs_mode;
> +	u32 val;
> +	u32 hs_workaround = 0;
> +
> +	/* Send the payload, if any */
> +	length = pkt->payload_length;
> +	payload = pkt->payload;
> +
> +	while (length >= 4) {
> +		val = *(u32 *)payload;
> +		hs_workaround |= !(val & 0xFFFF00);
> +		nwl_dsi_write(dsi, NWL_DSI_TX_PAYLOAD, val);
> +		payload += 4;
> +		length -= 4;
> +	}
> +	/* Send the rest of the payload */
> +	val = 0;
> +	switch (length) {
> +	case 3:
> +		val |= payload[2] << 16;
> +		fallthrough;
> +	case 2:
> +		val |= payload[1] << 8;
> +		hs_workaround |= !(val & 0xFFFF00);
> +		fallthrough;
> +	case 1:
> +		val |= payload[0];
> +		nwl_dsi_write(dsi, NWL_DSI_TX_PAYLOAD, val);
> +		break;
> +	}
> +	xfer->tx_len = pkt->payload_length;
> +
> +	/*
> +	 * Send the header
> +	 * header[0] = Virtual Channel + Data Type
> +	 * header[1] = Word Count LSB (LP) or first param (SP)
> +	 * header[2] = Word Count MSB (LP) or second param (SP)
> +	 */
> +	word_count = pkt->header[1] | (pkt->header[2] << 8);
> +	if (hs_workaround && (dsi->quirks & E11418_HS_MODE_QUIRK)) {
> +		DRM_DEV_DEBUG_DRIVER(dsi->dev,
> +				     "Using hs mode workaround for cmd 0x%x\n",
> +				     xfer->cmd);
> +		hs_mode = 1;
> +	} else {
> +		hs_mode = (xfer->msg->flags & MIPI_DSI_MSG_USE_LPM) ? 0 : 1;
> +	}
> +	val = NWL_DSI_WC(word_count) | NWL_DSI_TX_VC(xfer->msg->channel) |
> +	      NWL_DSI_TX_DT(xfer->msg->type) | NWL_DSI_HS_SEL(hs_mode) |
> +	      NWL_DSI_BTA_TX(xfer->need_bta);
> +	nwl_dsi_write(dsi, NWL_DSI_PKT_CONTROL, val);
> +
> +	/* Send packet command */
> +	nwl_dsi_write(dsi, NWL_DSI_SEND_PACKET, 0x1);
> +}
> +
> +static ssize_t nwl_dsi_host_transfer(struct mipi_dsi_host *dsi_host,
> +				     const struct mipi_dsi_msg *msg)
> +{
> +	struct nwl_dsi *dsi = container_of(dsi_host, struct nwl_dsi, dsi_host);
> +	struct nwl_dsi_transfer xfer;
> +	ssize_t ret = 0;
> +
> +	/* Create packet to be sent */
> +	dsi->xfer = &xfer;
> +	ret = mipi_dsi_create_packet(&xfer.packet, msg);
> +	if (ret < 0) {
> +		dsi->xfer = NULL;
> +		return ret;
> +	}
> +
> +	if ((msg->type & MIPI_DSI_GENERIC_READ_REQUEST_0_PARAM ||
> +	     msg->type & MIPI_DSI_GENERIC_READ_REQUEST_1_PARAM ||
> +	     msg->type & MIPI_DSI_GENERIC_READ_REQUEST_2_PARAM ||
> +	     msg->type & MIPI_DSI_DCS_READ) &&
> +	    msg->rx_len > 0 && msg->rx_buf != NULL)
> +		xfer.direction = DSI_PACKET_RECEIVE;
> +	else
> +		xfer.direction = DSI_PACKET_SEND;
> +
> +	xfer.need_bta = (xfer.direction == DSI_PACKET_RECEIVE);
> +	xfer.need_bta |= (msg->flags & MIPI_DSI_MSG_REQ_ACK) ? 1 : 0;
> +	xfer.msg = msg;
> +	xfer.status = -ETIMEDOUT;
> +	xfer.rx_word_count = 0;
> +	xfer.rx_len = 0;
> +	xfer.cmd = 0x00;
> +	if (msg->tx_len > 0)
> +		xfer.cmd = ((u8 *)(msg->tx_buf))[0];
> +	init_completion(&xfer.completed);
> +
> +	ret = clk_prepare_enable(dsi->rx_esc_clk);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(dsi->dev, "Failed to enable rx_esc clk: %zd\n",
> +			      ret);
> +		return ret;
> +	}
> +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "Enabled rx_esc clk @%lu Hz\n",
> +			     clk_get_rate(dsi->rx_esc_clk));
> +
> +	/* Initiate the DSI packet transmision */
> +	nwl_dsi_begin_transmission(dsi);
> +
> +	if (!wait_for_completion_timeout(&xfer.completed,
> +					 NWL_DSI_MIPI_FIFO_TIMEOUT)) {
> +		DRM_DEV_ERROR(dsi_host->dev, "[%02X] DSI transfer timed out\n",
> +			      xfer.cmd);
> +		ret = -ETIMEDOUT;
> +	} else {
> +		ret = xfer.status;
> +	}
> +
> +	clk_disable_unprepare(dsi->rx_esc_clk);
> +
> +	return ret;
> +}
> +
> +static const struct mipi_dsi_host_ops nwl_dsi_host_ops = {
> +	.attach = nwl_dsi_host_attach,
> +	.transfer = nwl_dsi_host_transfer,
> +};
> +
> +static irqreturn_t nwl_dsi_irq_handler(int irq, void *data)
> +{
> +	u32 irq_status;
> +	struct nwl_dsi *dsi = data;
> +
> +	irq_status = nwl_dsi_read(dsi, NWL_DSI_IRQ_STATUS);
> +
> +	if (irq_status & NWL_DSI_TX_FIFO_OVFLW)
> +		DRM_DEV_ERROR_RATELIMITED(dsi->dev, "tx fifo overflow\n");
> +
> +	if (irq_status & NWL_DSI_HS_TX_TIMEOUT)
> +		DRM_DEV_ERROR_RATELIMITED(dsi->dev, "HS tx timeout\n");
> +
> +	if (irq_status & NWL_DSI_TX_PKT_DONE ||
> +	    irq_status & NWL_DSI_RX_PKT_HDR_RCVD ||
> +	    irq_status & NWL_DSI_RX_PKT_PAYLOAD_DATA_RCVD)
> +		nwl_dsi_finish_transmission(dsi, irq_status);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int nwl_dsi_enable(struct nwl_dsi *dsi)
> +{
> +	struct device *dev = dsi->dev;
> +	union phy_configure_opts *phy_cfg = &dsi->phy_cfg;
> +	int ret;
> +
> +	if (!dsi->lanes) {
> +		DRM_DEV_ERROR(dev, "Need DSI lanes: %d\n", dsi->lanes);
> +		return -EINVAL;
> +	}
> +
> +	ret = phy_init(dsi->phy);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(dev, "Failed to init DSI phy: %d\n", ret);
> +		return ret;
> +	}
> +
> +	ret = phy_configure(dsi->phy, phy_cfg);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(dev, "Failed to configure DSI phy: %d\n", ret);
> +		goto uninit_phy;
> +	}
> +
> +	ret = clk_prepare_enable(dsi->tx_esc_clk);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(dsi->dev, "Failed to enable tx_esc clk: %d\n",
> +			      ret);
> +		goto uninit_phy;
> +	}
> +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "Enabled tx_esc clk @%lu Hz\n",
> +			     clk_get_rate(dsi->tx_esc_clk));
> +
> +	ret = nwl_dsi_config_host(dsi);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(dev, "Failed to set up DSI: %d", ret);
> +		goto disable_clock;
> +	}
> +
> +	ret = nwl_dsi_config_dpi(dsi);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(dev, "Failed to set up DPI: %d", ret);
> +		goto disable_clock;
> +	}
> +
> +	ret = phy_power_on(dsi->phy);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(dev, "Failed to power on DPHY (%d)\n", ret);
> +		goto disable_clock;
> +	}
> +
> +	ret = nwl_dsi_init_interrupts(dsi);
> +	if (ret < 0)
> +		goto power_off_phy;
> +
> +	return ret;
> +
> +power_off_phy:
> +	phy_power_off(dsi->phy);
> +disable_clock:
> +	clk_disable_unprepare(dsi->tx_esc_clk);
> +uninit_phy:
> +	phy_exit(dsi->phy);
> +
> +	return ret;
> +}
> +
> +static int nwl_dsi_disable(struct nwl_dsi *dsi)
> +{
> +	struct device *dev = dsi->dev;
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "Disabling clocks and phy\n");
> +
> +	phy_power_off(dsi->phy);
> +	phy_exit(dsi->phy);
> +
> +	/* Disabling the clock before the phy breaks enabling dsi again */
> +	clk_disable_unprepare(dsi->tx_esc_clk);
> +
> +	return 0;
> +}
> +
> +static void nwl_dsi_bridge_disable(struct drm_bridge *bridge)
> +{
> +	struct nwl_dsi *dsi = bridge_to_dsi(bridge);
> +	int ret;
> +
> +	nwl_dsi_disable(dsi);
> +
> +	ret = reset_control_assert(dsi->rst_dpi);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(dsi->dev, "Failed to assert DPI: %d\n", ret);
> +		return;
> +	}
> +	ret = reset_control_assert(dsi->rst_byte);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(dsi->dev, "Failed to assert ESC: %d\n", ret);
> +		return;
> +	}
> +	ret = reset_control_assert(dsi->rst_esc);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(dsi->dev, "Failed to assert BYTE: %d\n", ret);
> +		return;
> +	}
> +	ret = reset_control_assert(dsi->rst_pclk);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(dsi->dev, "Failed to assert PCLK: %d\n", ret);
> +		return;
> +	}
> +
> +	clk_disable_unprepare(dsi->core_clk);
> +	clk_disable_unprepare(dsi->lcdif_clk);
> +
> +	pm_runtime_put(dsi->dev);
> +}
> +
> +static int nwl_dsi_get_dphy_params(struct nwl_dsi *dsi,
> +				   const struct drm_display_mode *mode,
> +				   union phy_configure_opts *phy_opts)
> +{
> +	unsigned long rate;
> +	int ret;
> +
> +	if (dsi->lanes < 1 || dsi->lanes > 4)
> +		return -EINVAL;
> +
> +	/*
> +	 * So far the DPHY spec minimal timings work for both mixel
> +	 * dphy and nwl dsi host
> +	 */
> +	ret = phy_mipi_dphy_get_default_config(
> +		mode->clock * 1000,
> +		mipi_dsi_pixel_format_to_bpp(dsi->format), dsi->lanes,
> +		&phy_opts->mipi_dphy);
> +	if (ret < 0)
> +		return ret;
> +
> +	rate = clk_get_rate(dsi->tx_esc_clk);
> +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "LP clk is @%lu Hz\n", rate);
> +	phy_opts->mipi_dphy.lp_clk_rate = rate;
> +
> +	return 0;
> +}
> +
> +static bool nwl_dsi_bridge_mode_fixup(struct drm_bridge *bridge,
> +				      const struct drm_display_mode *mode,
> +				      struct drm_display_mode *adjusted_mode)
> +{
> +	/* At least LCDIF + NWL needs active high sync */
> +	adjusted_mode->flags |= (DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC);
> +	adjusted_mode->flags &= ~(DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC);
> +
> +	return true;
> +}
> +
> +static enum drm_mode_status
> +nwl_dsi_bridge_mode_valid(struct drm_bridge *bridge,
> +			  const struct drm_display_mode *mode)
> +{
> +	struct nwl_dsi *dsi = bridge_to_dsi(bridge);
> +	int bpp = mipi_dsi_pixel_format_to_bpp(dsi->format);
> +
> +	if (mode->clock * bpp > 15000000 * dsi->lanes)
> +		return MODE_CLOCK_HIGH;
> +
> +	if (mode->clock * bpp < 80000 * dsi->lanes)
> +		return MODE_CLOCK_LOW;
> +
> +	return MODE_OK;
> +}
> +
> +static void
> +nwl_dsi_bridge_mode_set(struct drm_bridge *bridge,
> +			const struct drm_display_mode *mode,
> +			const struct drm_display_mode *adjusted_mode)
> +{
> +	struct nwl_dsi *dsi = bridge_to_dsi(bridge);
> +	struct device *dev = dsi->dev;
> +	union phy_configure_opts new_cfg;
> +	unsigned long phy_ref_rate;
> +	int ret;
> +
> +	ret = nwl_dsi_get_dphy_params(dsi, adjusted_mode, &new_cfg);
> +	if (ret < 0)
> +		return;
> +
> +	/*
> +	 * If hs clock is unchanged, we're all good - all parameters are
> +	 * derived from it atm.
> +	 */
> +	if (new_cfg.mipi_dphy.hs_clk_rate == dsi->phy_cfg.mipi_dphy.hs_clk_rate)
> +		return;
> +
> +	phy_ref_rate = clk_get_rate(dsi->phy_ref_clk);
> +	DRM_DEV_DEBUG_DRIVER(dev, "PHY at ref rate: %lu\n", phy_ref_rate);
> +	/* Save the new desired phy config */
> +	memcpy(&dsi->phy_cfg, &new_cfg, sizeof(new_cfg));
> +
> +	memcpy(&dsi->mode, adjusted_mode, sizeof(dsi->mode));
> +	drm_mode_debug_printmodeline(adjusted_mode);
> +}
> +
> +static void nwl_dsi_bridge_pre_enable(struct drm_bridge *bridge)
> +{
> +	struct nwl_dsi *dsi = bridge_to_dsi(bridge);
> +	int ret;
> +
> +	pm_runtime_get_sync(dsi->dev);
> +
> +	if (clk_prepare_enable(dsi->lcdif_clk) < 0)
> +		return;
> +	if (clk_prepare_enable(dsi->core_clk) < 0)
> +		return;
> +
> +	/* Step 1 from DSI reset-out instructions */
> +	ret = reset_control_deassert(dsi->rst_pclk);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(dsi->dev, "Failed to deassert PCLK: %d\n", ret);
> +		return;
> +	}
> +
> +	/* Step 2 from DSI reset-out instructions */
> +	nwl_dsi_enable(dsi);
> +
> +	/* Step 3 from DSI reset-out instructions */
> +	ret = reset_control_deassert(dsi->rst_esc);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(dsi->dev, "Failed to deassert ESC: %d\n", ret);
> +		return;
> +	}
> +	ret = reset_control_deassert(dsi->rst_byte);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(dsi->dev, "Failed to deassert BYTE: %d\n", ret);
> +		return;
> +	}
> +}
> +
> +static void nwl_dsi_bridge_enable(struct drm_bridge *bridge)
> +{
> +	struct nwl_dsi *dsi = bridge_to_dsi(bridge);
> +	int ret;
> +
> +	/* Step 5 from DSI reset-out instructions */
> +	ret = reset_control_deassert(dsi->rst_dpi);
> +	if (ret < 0)
> +		DRM_DEV_ERROR(dsi->dev, "Failed to deassert DPI: %d\n", ret);
> +}
> +
> +static int nwl_dsi_bridge_attach(struct drm_bridge *bridge,
> +				 enum drm_bridge_attach_flags flags)
> +{
> +	struct nwl_dsi *dsi = bridge_to_dsi(bridge);
> +	struct drm_bridge *panel_bridge;
> +	struct drm_panel *panel;
> +	int ret;
> +
> +	if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR)
> +		return -EINVAL;

Any chance this driver could be fixed to make connection optional?
Also, other drivers are more friednly and print something if the
DRM_BRIDGE_ATTACH_NO_CONNECTOR flag is set.

	Sam

> +
> +	ret = drm_of_find_panel_or_bridge(dsi->dev->of_node, 1, 0, &panel,
> +					  &panel_bridge);
> +	if (ret)
> +		return ret;
> +
> +	if (panel) {
> +		panel_bridge = drm_panel_bridge_add(panel);
> +		if (IS_ERR(panel_bridge))
> +			return PTR_ERR(panel_bridge);
> +	}
> +	dsi->panel_bridge = panel_bridge;
> +
> +	if (!dsi->panel_bridge)
> +		return -EPROBE_DEFER;
> +
> +	return drm_bridge_attach(bridge->encoder, dsi->panel_bridge, bridge,
> +				 flags);
> +}
> +
> +static void nwl_dsi_bridge_detach(struct drm_bridge *bridge)
> +{	struct nwl_dsi *dsi = bridge_to_dsi(bridge);
> +
> +	drm_of_panel_bridge_remove(dsi->dev->of_node, 1, 0);
> +	return;
> +}
> +
> +static const struct drm_bridge_funcs nwl_dsi_bridge_funcs = {
> +	.pre_enable = nwl_dsi_bridge_pre_enable,
> +	.enable     = nwl_dsi_bridge_enable,
> +	.disable    = nwl_dsi_bridge_disable,
> +	.mode_fixup = nwl_dsi_bridge_mode_fixup,
> +	.mode_set   = nwl_dsi_bridge_mode_set,
> +	.mode_valid = nwl_dsi_bridge_mode_valid,
> +	.attach	    = nwl_dsi_bridge_attach,
> +	.detach	    = nwl_dsi_bridge_detach,
> +};
> +
> +static int nwl_dsi_parse_dt(struct nwl_dsi *dsi)
> +{
> +	struct platform_device *pdev = to_platform_device(dsi->dev);
> +	struct clk *clk;
> +	void __iomem *base;
> +	int ret;
> +
> +	dsi->phy = devm_phy_get(dsi->dev, "dphy");
> +	if (IS_ERR(dsi->phy)) {
> +		ret = PTR_ERR(dsi->phy);
> +		if (ret != -EPROBE_DEFER)
> +			DRM_DEV_ERROR(dsi->dev, "Could not get PHY: %d\n", ret);
> +		return ret;
> +	}
> +
> +	clk = devm_clk_get(dsi->dev, "lcdif");
> +	if (IS_ERR(clk)) {
> +		ret = PTR_ERR(clk);
> +		DRM_DEV_ERROR(dsi->dev, "Failed to get lcdif clock: %d\n",
> +			      ret);
> +		return ret;
> +	}
> +	dsi->lcdif_clk = clk;
> +
> +	clk = devm_clk_get(dsi->dev, "core");
> +	if (IS_ERR(clk)) {
> +		ret = PTR_ERR(clk);
> +		DRM_DEV_ERROR(dsi->dev, "Failed to get core clock: %d\n",
> +			      ret);
> +		return ret;
> +	}
> +	dsi->core_clk = clk;
> +
> +
> +	clk = devm_clk_get(dsi->dev, "phy_ref");
> +	if (IS_ERR(clk)) {
> +		ret = PTR_ERR(clk);
> +		DRM_DEV_ERROR(dsi->dev, "Failed to get phy_ref clock: %d\n",
> +			      ret);
> +		return ret;
> +	}
> +	dsi->phy_ref_clk = clk;
> +
> +	clk = devm_clk_get(dsi->dev, "rx_esc");
> +	if (IS_ERR(clk)) {
> +		ret = PTR_ERR(clk);
> +		DRM_DEV_ERROR(dsi->dev, "Failed to get rx_esc clock: %d\n",
> +			      ret);
> +		return ret;
> +	}
> +	dsi->rx_esc_clk = clk;
> +
> +	clk = devm_clk_get(dsi->dev, "tx_esc");
> +	if (IS_ERR(clk)) {
> +		ret = PTR_ERR(clk);
> +		DRM_DEV_ERROR(dsi->dev, "Failed to get tx_esc clock: %d\n",
> +			      ret);
> +		return ret;
> +	}
> +	dsi->tx_esc_clk = clk;
> +
> +	dsi->mux = devm_mux_control_get(dsi->dev, NULL);
> +	if (IS_ERR(dsi->mux)) {
> +		ret = PTR_ERR(dsi->mux);
> +		if (ret != -EPROBE_DEFER)
> +			DRM_DEV_ERROR(dsi->dev, "Failed to get mux: %d\n", ret);
> +		return ret;
> +	}
> +
> +	base = devm_platform_ioremap_resource(pdev, 0);
> +	if (IS_ERR(base))
> +		return PTR_ERR(base);
> +
> +	dsi->regmap =
> +		devm_regmap_init_mmio(dsi->dev, base, &nwl_dsi_regmap_config);
> +	if (IS_ERR(dsi->regmap)) {
> +		ret = PTR_ERR(dsi->regmap);
> +		DRM_DEV_ERROR(dsi->dev, "Failed to create NWL DSI regmap: %d\n",
> +			      ret);
> +		return ret;
> +	}
> +
> +	dsi->irq = platform_get_irq(pdev, 0);
> +	if (dsi->irq < 0) {
> +		DRM_DEV_ERROR(dsi->dev, "Failed to get device IRQ: %d\n",
> +			      dsi->irq);
> +		return dsi->irq;
> +	}
> +
> +	dsi->rst_pclk = devm_reset_control_get_exclusive(dsi->dev, "pclk");
> +	if (IS_ERR(dsi->rst_pclk)) {
> +		DRM_DEV_ERROR(dsi->dev, "Failed to get pclk reset: %ld\n",
> +			      PTR_ERR(dsi->rst_pclk));
> +		return PTR_ERR(dsi->rst_pclk);
> +	}
> +	dsi->rst_byte = devm_reset_control_get_exclusive(dsi->dev, "byte");
> +	if (IS_ERR(dsi->rst_byte)) {
> +		DRM_DEV_ERROR(dsi->dev, "Failed to get byte reset: %ld\n",
> +			      PTR_ERR(dsi->rst_byte));
> +		return PTR_ERR(dsi->rst_byte);
> +	}
> +	dsi->rst_esc = devm_reset_control_get_exclusive(dsi->dev, "esc");
> +	if (IS_ERR(dsi->rst_esc)) {
> +		DRM_DEV_ERROR(dsi->dev, "Failed to get esc reset: %ld\n",
> +			      PTR_ERR(dsi->rst_esc));
> +		return PTR_ERR(dsi->rst_esc);
> +	}
> +	dsi->rst_dpi = devm_reset_control_get_exclusive(dsi->dev, "dpi");
> +	if (IS_ERR(dsi->rst_dpi)) {
> +		DRM_DEV_ERROR(dsi->dev, "Failed to get dpi reset: %ld\n",
> +			      PTR_ERR(dsi->rst_dpi));
> +		return PTR_ERR(dsi->rst_dpi);
> +	}
> +	return 0;
> +}
> +
> +static int nwl_dsi_select_input(struct nwl_dsi *dsi)
> +{
> +	struct device_node *remote;
> +	u32 use_dcss = 1;
> +	int ret;
> +
> +	remote = of_graph_get_remote_node(dsi->dev->of_node, 0,
> +					  NWL_DSI_ENDPOINT_LCDIF);
> +	if (remote) {
> +		use_dcss = 0;
> +	} else {
> +		remote = of_graph_get_remote_node(dsi->dev->of_node, 0,
> +						  NWL_DSI_ENDPOINT_DCSS);
> +		if (!remote) {
> +			DRM_DEV_ERROR(dsi->dev,
> +				      "No valid input endpoint found\n");
> +			return -EINVAL;
> +		}
> +	}
> +
> +	DRM_DEV_INFO(dsi->dev, "Using %s as input source\n",
> +		     (use_dcss) ? "DCSS" : "LCDIF");
> +	ret = mux_control_try_select(dsi->mux, use_dcss);
> +	if (ret < 0)
> +		DRM_DEV_ERROR(dsi->dev, "Failed to select input: %d\n", ret);
> +
> +	of_node_put(remote);
> +	return ret;
> +}
> +
> +static int nwl_dsi_deselect_input(struct nwl_dsi *dsi)
> +{
> +	int ret;
> +
> +	ret = mux_control_deselect(dsi->mux);
> +	if (ret < 0)
> +		DRM_DEV_ERROR(dsi->dev, "Failed to deselect input: %d\n", ret);
> +
> +	return ret;
> +}
> +
> +static const struct drm_bridge_timings nwl_dsi_timings = {
> +	.input_bus_flags = DRM_BUS_FLAG_DE_LOW,
> +};
> +
> +static const struct of_device_id nwl_dsi_dt_ids[] = {
> +	{ .compatible = "fsl,imx8mq-nwl-dsi", },
> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, nwl_dsi_dt_ids);
> +
> +static const struct soc_device_attribute nwl_dsi_quirks_match[] = {
> +	{ .soc_id = "i.MX8MQ", .revision = "2.0",
> +	  .data = (void *)E11418_HS_MODE_QUIRK },
> +	{ /* sentinel. */ },
> +};
> +
> +static int nwl_dsi_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	const struct soc_device_attribute *attr;
> +	struct nwl_dsi *dsi;
> +	int ret;
> +
> +	dsi = devm_kzalloc(dev, sizeof(*dsi), GFP_KERNEL);
> +	if (!dsi)
> +		return -ENOMEM;
> +
> +	dsi->dev = dev;
> +
> +	ret = nwl_dsi_parse_dt(dsi);
> +	if (ret)
> +		return ret;
> +
> +	ret = devm_request_irq(dev, dsi->irq, nwl_dsi_irq_handler, 0,
> +			       dev_name(dev), dsi);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(dev, "Failed to request IRQ %d: %d\n", dsi->irq,
> +			      ret);
> +		return ret;
> +	}
> +
> +	dsi->dsi_host.ops = &nwl_dsi_host_ops;
> +	dsi->dsi_host.dev = dev;
> +	ret = mipi_dsi_host_register(&dsi->dsi_host);
> +	if (ret) {
> +		DRM_DEV_ERROR(dev, "Failed to register MIPI host: %d\n", ret);
> +		return ret;
> +	}
> +
> +	attr = soc_device_match(nwl_dsi_quirks_match);
> +	if (attr)
> +		dsi->quirks = (uintptr_t)attr->data;
> +
> +	dsi->bridge.driver_private = dsi;
> +	dsi->bridge.funcs = &nwl_dsi_bridge_funcs;
> +	dsi->bridge.of_node = dev->of_node;
> +	dsi->bridge.timings = &nwl_dsi_timings;
> +
> +	dev_set_drvdata(dev, dsi);
> +	pm_runtime_enable(dev);
> +
> +	ret = nwl_dsi_select_input(dsi);
> +	if (ret < 0) {
> +		mipi_dsi_host_unregister(&dsi->dsi_host);
> +		return ret;
> +	}
> +
> +	drm_bridge_add(&dsi->bridge);
> +	return 0;
> +}
> +
> +static int nwl_dsi_remove(struct platform_device *pdev)
> +{
> +	struct nwl_dsi *dsi = platform_get_drvdata(pdev);
> +
> +	nwl_dsi_deselect_input(dsi);
> +	mipi_dsi_host_unregister(&dsi->dsi_host);
> +	drm_bridge_remove(&dsi->bridge);
> +	pm_runtime_disable(&pdev->dev);
> +	return 0;
> +}
> +
> +static struct platform_driver nwl_dsi_driver = {
> +	.probe		= nwl_dsi_probe,
> +	.remove		= nwl_dsi_remove,
> +	.driver		= {
> +		.of_match_table = nwl_dsi_dt_ids,
> +		.name	= DRV_NAME,
> +	},
> +};
> +
> +module_platform_driver(nwl_dsi_driver);
> +
> +MODULE_AUTHOR("NXP Semiconductor");
> +MODULE_AUTHOR("Purism SPC");
> +MODULE_DESCRIPTION("Northwest Logic MIPI-DSI driver");
> +MODULE_LICENSE("GPL"); /* GPLv2 or later */
> diff --git a/drivers/gpu/drm/bridge/nwl-dsi.h b/drivers/gpu/drm/bridge/nwl-dsi.h
> new file mode 100644
> index 000000000000..a247a8a11c7c
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/nwl-dsi.h
> @@ -0,0 +1,144 @@
> +/* SPDX-License-Identifier: GPL-2.0+ */
> +/*
> + * NWL MIPI DSI host driver
> + *
> + * Copyright (C) 2017 NXP
> + * Copyright (C) 2019 Purism SPC
> + */
> +#ifndef __NWL_DSI_H__
> +#define __NWL_DSI_H__
> +
> +/* DSI HOST registers */
> +#define NWL_DSI_CFG_NUM_LANES			0x0
> +#define NWL_DSI_CFG_NONCONTINUOUS_CLK		0x4
> +#define NWL_DSI_CFG_T_PRE			0x8
> +#define NWL_DSI_CFG_T_POST			0xc
> +#define NWL_DSI_CFG_TX_GAP			0x10
> +#define NWL_DSI_CFG_AUTOINSERT_EOTP		0x14
> +#define NWL_DSI_CFG_EXTRA_CMDS_AFTER_EOTP	0x18
> +#define NWL_DSI_CFG_HTX_TO_COUNT		0x1c
> +#define NWL_DSI_CFG_LRX_H_TO_COUNT		0x20
> +#define NWL_DSI_CFG_BTA_H_TO_COUNT		0x24
> +#define NWL_DSI_CFG_TWAKEUP			0x28
> +#define NWL_DSI_CFG_STATUS_OUT			0x2c
> +#define NWL_DSI_RX_ERROR_STATUS			0x30
> +
> +/* DSI DPI registers */
> +#define NWL_DSI_PIXEL_PAYLOAD_SIZE		0x200
> +#define NWL_DSI_PIXEL_FIFO_SEND_LEVEL		0x204
> +#define NWL_DSI_INTERFACE_COLOR_CODING		0x208
> +#define NWL_DSI_PIXEL_FORMAT			0x20c
> +#define NWL_DSI_VSYNC_POLARITY			0x210
> +#define NWL_DSI_VSYNC_POLARITY_ACTIVE_LOW	0
> +#define NWL_DSI_VSYNC_POLARITY_ACTIVE_HIGH	BIT(1)
> +
> +#define NWL_DSI_HSYNC_POLARITY			0x214
> +#define NWL_DSI_HSYNC_POLARITY_ACTIVE_LOW	0
> +#define NWL_DSI_HSYNC_POLARITY_ACTIVE_HIGH	BIT(1)
> +
> +#define NWL_DSI_VIDEO_MODE			0x218
> +#define NWL_DSI_HFP				0x21c
> +#define NWL_DSI_HBP				0x220
> +#define NWL_DSI_HSA				0x224
> +#define NWL_DSI_ENABLE_MULT_PKTS		0x228
> +#define NWL_DSI_VBP				0x22c
> +#define NWL_DSI_VFP				0x230
> +#define NWL_DSI_BLLP_MODE			0x234
> +#define NWL_DSI_USE_NULL_PKT_BLLP		0x238
> +#define NWL_DSI_VACTIVE				0x23c
> +#define NWL_DSI_VC				0x240
> +
> +/* DSI APB PKT control */
> +#define NWL_DSI_TX_PAYLOAD			0x280
> +#define NWL_DSI_PKT_CONTROL			0x284
> +#define NWL_DSI_SEND_PACKET			0x288
> +#define NWL_DSI_PKT_STATUS			0x28c
> +#define NWL_DSI_PKT_FIFO_WR_LEVEL		0x290
> +#define NWL_DSI_PKT_FIFO_RD_LEVEL		0x294
> +#define NWL_DSI_RX_PAYLOAD			0x298
> +#define NWL_DSI_RX_PKT_HEADER			0x29c
> +
> +/* DSI IRQ handling */
> +#define NWL_DSI_IRQ_STATUS			0x2a0
> +#define NWL_DSI_SM_NOT_IDLE			BIT(0)
> +#define NWL_DSI_TX_PKT_DONE			BIT(1)
> +#define NWL_DSI_DPHY_DIRECTION			BIT(2)
> +#define NWL_DSI_TX_FIFO_OVFLW			BIT(3)
> +#define NWL_DSI_TX_FIFO_UDFLW			BIT(4)
> +#define NWL_DSI_RX_FIFO_OVFLW			BIT(5)
> +#define NWL_DSI_RX_FIFO_UDFLW			BIT(6)
> +#define NWL_DSI_RX_PKT_HDR_RCVD			BIT(7)
> +#define NWL_DSI_RX_PKT_PAYLOAD_DATA_RCVD	BIT(8)
> +#define NWL_DSI_BTA_TIMEOUT			BIT(29)
> +#define NWL_DSI_LP_RX_TIMEOUT			BIT(30)
> +#define NWL_DSI_HS_TX_TIMEOUT			BIT(31)
> +
> +#define NWL_DSI_IRQ_STATUS2			0x2a4
> +#define NWL_DSI_SINGLE_BIT_ECC_ERR		BIT(0)
> +#define NWL_DSI_MULTI_BIT_ECC_ERR		BIT(1)
> +#define NWL_DSI_CRC_ERR				BIT(2)
> +
> +#define NWL_DSI_IRQ_MASK			0x2a8
> +#define NWL_DSI_SM_NOT_IDLE_MASK		BIT(0)
> +#define NWL_DSI_TX_PKT_DONE_MASK		BIT(1)
> +#define NWL_DSI_DPHY_DIRECTION_MASK		BIT(2)
> +#define NWL_DSI_TX_FIFO_OVFLW_MASK		BIT(3)
> +#define NWL_DSI_TX_FIFO_UDFLW_MASK		BIT(4)
> +#define NWL_DSI_RX_FIFO_OVFLW_MASK		BIT(5)
> +#define NWL_DSI_RX_FIFO_UDFLW_MASK		BIT(6)
> +#define NWL_DSI_RX_PKT_HDR_RCVD_MASK		BIT(7)
> +#define NWL_DSI_RX_PKT_PAYLOAD_DATA_RCVD_MASK	BIT(8)
> +#define NWL_DSI_BTA_TIMEOUT_MASK		BIT(29)
> +#define NWL_DSI_LP_RX_TIMEOUT_MASK		BIT(30)
> +#define NWL_DSI_HS_TX_TIMEOUT_MASK		BIT(31)
> +
> +#define NWL_DSI_IRQ_MASK2			0x2ac
> +#define NWL_DSI_SINGLE_BIT_ECC_ERR_MASK		BIT(0)
> +#define NWL_DSI_MULTI_BIT_ECC_ERR_MASK		BIT(1)
> +#define NWL_DSI_CRC_ERR_MASK			BIT(2)
> +
> +/*
> + * PKT_CONTROL format:
> + * [15: 0] - word count
> + * [17:16] - virtual channel
> + * [23:18] - data type
> + * [24]	   - LP or HS select (0 - LP, 1 - HS)
> + * [25]	   - perform BTA after packet is sent
> + * [26]	   - perform BTA only, no packet tx
> + */
> +#define NWL_DSI_WC(x)		FIELD_PREP(GENMASK(15, 0), (x))
> +#define NWL_DSI_TX_VC(x)	FIELD_PREP(GENMASK(17, 16), (x))
> +#define NWL_DSI_TX_DT(x)	FIELD_PREP(GENMASK(23, 18), (x))
> +#define NWL_DSI_HS_SEL(x)	FIELD_PREP(GENMASK(24, 24), (x))
> +#define NWL_DSI_BTA_TX(x)	FIELD_PREP(GENMASK(25, 25), (x))
> +#define NWL_DSI_BTA_NO_TX(x)	FIELD_PREP(GENMASK(26, 26), (x))
> +
> +/*
> + * RX_PKT_HEADER format:
> + * [15: 0] - word count
> + * [21:16] - data type
> + * [23:22] - virtual channel
> + */
> +#define NWL_DSI_RX_DT(x)	FIELD_GET(GENMASK(21, 16), (x))
> +#define NWL_DSI_RX_VC(x)	FIELD_GET(GENMASK(23, 22), (x))
> +
> +/* DSI Video mode */
> +#define NWL_DSI_VM_BURST_MODE_WITH_SYNC_PULSES		0
> +#define NWL_DSI_VM_NON_BURST_MODE_WITH_SYNC_EVENTS	BIT(0)
> +#define NWL_DSI_VM_BURST_MODE				BIT(1)
> +
> +/* * DPI color coding */
> +#define NWL_DSI_DPI_16_BIT_565_PACKED	0
> +#define NWL_DSI_DPI_16_BIT_565_ALIGNED	1
> +#define NWL_DSI_DPI_16_BIT_565_SHIFTED	2
> +#define NWL_DSI_DPI_18_BIT_PACKED	3
> +#define NWL_DSI_DPI_18_BIT_ALIGNED	4
> +#define NWL_DSI_DPI_24_BIT		5
> +
> +/* * DPI Pixel format */
> +#define NWL_DSI_PIXEL_FORMAT_16  0
> +#define NWL_DSI_PIXEL_FORMAT_18  BIT(0)
> +#define NWL_DSI_PIXEL_FORMAT_18L BIT(1)
> +#define NWL_DSI_PIXEL_FORMAT_24  (BIT(0) | BIT(1))
> +
> +#endif /* __NWL_DSI_H__ */
> -- 
> 2.23.0
>