Re: [PATCH 4/6] drm/bridge: Add Analogix anx6345 support

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Torsten,

Thank you for the patch.

On Thu, May 23, 2019 at 08:53:56AM +0200, Torsten Duwe wrote:
> From: Icenowy Zheng <icenowy@aosc.io>
> 
> The ANX6345 is an ultra-low power DisplayPower/eDP transmitter designed
> for portable devices. This driver adds initial support for RGB to eDP
> mode, without HPD and interrupts.
> 
> This is a configuration usually seen in eDP applications.
> 
> Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
> Signed-off-by: Vasily Khoruzhick <anarsoul@gmail.com>
> Signed-off-by: Torsten Duwe <duwe@suse.de>
> ---
>  drivers/gpu/drm/bridge/analogix/Kconfig            |  11 +
>  drivers/gpu/drm/bridge/analogix/Makefile           |   1 +
>  drivers/gpu/drm/bridge/analogix/analogix-anx6345.c | 808 +++++++++++++++++++++
>  .../gpu/drm/bridge/analogix/analogix-i2c-dptx.c    |   2 +-
>  .../gpu/drm/bridge/analogix/analogix-i2c-dptx.h    |   8 +
>  .../drm/bridge/analogix/analogix-i2c-txcommon.h    |   3 +
>  6 files changed, 832 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/gpu/drm/bridge/analogix/analogix-anx6345.c
> 
> diff --git a/drivers/gpu/drm/bridge/analogix/Kconfig b/drivers/gpu/drm/bridge/analogix/Kconfig
> index ed2d05c12546..3c6ec535d361 100644
> --- a/drivers/gpu/drm/bridge/analogix/Kconfig
> +++ b/drivers/gpu/drm/bridge/analogix/Kconfig
> @@ -1,3 +1,14 @@
>  # SPDX-License-Identifier: GPL-2.0-only
> +config DRM_ANALOGIX_ANX6345
> +	tristate "Analogix ANX6345 bridge"
> +	select DRM_ANALOGIX_DP_I2C
> +	select DRM_KMS_HELPER
> +	select REGMAP_I2C
> +	help
> +	  ANX6345 is an ultra-low Full-HD DisplayPort/eDP
> +	  transmitter designed for portable devices. The
> +	  ANX6345 transforms the LVTTL RGB output of an
> +	  application processor to eDP or DisplayPort.
> +
>  config DRM_ANALOGIX_ANX78XX
>  	tristate "Analogix ANX78XX bridge"
>  	select DRM_ANALOGIX_DP_I2C
> diff --git a/drivers/gpu/drm/bridge/analogix/Makefile b/drivers/gpu/drm/bridge/analogix/Makefile
> index 2d523b67487d..12fed7b04e1e 100644
> --- a/drivers/gpu/drm/bridge/analogix/Makefile
> +++ b/drivers/gpu/drm/bridge/analogix/Makefile
> @@ -1,6 +1,7 @@
>  # SPDX-License-Identifier: GPL-2.0-only
>  analogix_dp-objs := analogix_dp_core.o analogix_dp_reg.o
>  analogix_dp_i2c-objs := analogix-i2c-dptx.o
> +obj-$(CONFIG_DRM_ANALOGIX_ANX6345) += analogix-anx6345.o
>  obj-$(CONFIG_DRM_ANALOGIX_ANX78XX) += analogix-anx78xx.o
>  obj-$(CONFIG_DRM_ANALOGIX_DP) += analogix_dp.o
>  obj-$(CONFIG_DRM_ANALOGIX_DP_I2C) += analogix_dp_i2c.o
> diff --git a/drivers/gpu/drm/bridge/analogix/analogix-anx6345.c b/drivers/gpu/drm/bridge/analogix/analogix-anx6345.c
> new file mode 100644
> index 000000000000..36f38a9f042a
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/analogix/analogix-anx6345.c
> @@ -0,0 +1,810 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright(c) Icenowy Zheng <icenowy@aosc.io>
> + * Based on analogix-anx6345.c, which is:
> + *   Copyright(c) 2016, Analogix Semiconductor.
> + */
> +#include <linux/delay.h>
> +#include <linux/err.h>
> +#include <linux/interrupt.h>
> +#include <linux/i2c.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of_platform.h>
> +#include <linux/regmap.h>
> +#include <linux/types.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/regulator/consumer.h>
> +
> +#include <drm/drm_atomic_helper.h>
> +#include <drm/drm_probe_helper.h>
> +#include <drm/drm_crtc.h>
> +#include <drm/drm_crtc_helper.h>
> +#include <drm/drm_dp_helper.h>
> +#include <drm/drm_edid.h>
> +#include <drm/drm_of.h>
> +#include <drm/drm_print.h>
> +#include <drm/drm_panel.h>

Could you please sort the includes alphabetically to make it easer to
locate duplicates ?

> +
> +#include "analogix-i2c-dptx.h"
> +#include "analogix-i2c-txcommon.h"
> +
> +#define I2C_NUM_ADDRESSES	2
> +#define I2C_IDX_DPTX		0
> +#define I2C_IDX_TXCOM		1
> +
> +#define POLL_DELAY		50000 /* us */
> +#define POLL_TIMEOUT		5000000 /* us */
> +
> +static const u8 anx6345_i2c_addresses[] = {
> +	[I2C_IDX_DPTX]	= ANALOGIX_I2C_DPTX,
> +	[I2C_IDX_TXCOM]	= ANALOGIX_I2C_TXCOMMON,
> +};
> +
> +struct anx6345 {
> +	struct drm_dp_aux aux;
> +	struct drm_bridge bridge;
> +	struct i2c_client *client;
> +	struct edid *edid;
> +	struct drm_connector connector;
> +	struct drm_dp_link link;
> +	struct drm_panel *panel;
> +	struct regulator *dvdd12;
> +	struct regulator *dvdd25;
> +	struct gpio_desc *gpiod_reset;
> +	struct mutex lock;

Please add a comment to explain what the lock protects.

> +
> +	/*
> +	 * I2C Slave addresses of ANX6345 are mapped as DPTX and SYS
> +	 */

This can hold on a single line comment.

> +	struct i2c_client *i2c_clients[I2C_NUM_ADDRESSES];
> +	struct regmap *map[I2C_NUM_ADDRESSES];
> +
> +	u16 chipid;
> +	u8 dpcd[DP_RECEIVER_CAP_SIZE];
> +
> +	bool powered;
> +};
> +
> +static inline struct anx6345 *connector_to_anx6345(struct drm_connector *c)
> +{
> +	return container_of(c, struct anx6345, connector);
> +}
> +
> +static inline struct anx6345 *bridge_to_anx6345(struct drm_bridge *bridge)
> +{
> +	return container_of(bridge, struct anx6345, bridge);
> +}
> +
> +static int anx6345_set_bits(struct regmap *map, u8 reg, u8 mask)
> +{
> +	return regmap_update_bits(map, reg, mask, mask);
> +}
> +
> +static int anx6345_clear_bits(struct regmap *map, u8 reg, u8 mask)
> +{
> +	return regmap_update_bits(map, reg, mask, 0);
> +}
> +
> +static ssize_t anx6345_aux_transfer(struct drm_dp_aux *aux,
> +				    struct drm_dp_aux_msg *msg)
> +{
> +	struct anx6345 *anx6345 = container_of(aux, struct anx6345, aux);
> +
> +	return anx_aux_transfer(anx6345->map[I2C_IDX_DPTX], msg);
> +}
> +
> +static int anx6345_dp_link_training(struct anx6345 *anx6345)
> +{
> +	unsigned int value;
> +	u8 dp_bw;
> +	int err;
> +
> +	err = anx6345_clear_bits(anx6345->map[I2C_IDX_TXCOM],
> +				 SP_POWERDOWN_CTRL_REG,
> +				 SP_TOTAL_PD);
> +	if (err)
> +		return err;
> +
> +	err = drm_dp_dpcd_readb(&anx6345->aux, DP_MAX_LINK_RATE, &dp_bw);
> +	if (err < 0)
> +		return err;
> +
> +	switch (dp_bw) {
> +	case DP_LINK_BW_1_62:
> +	case DP_LINK_BW_2_7:
> +		break;
> +
> +	default:
> +		DRM_DEBUG_KMS("DP bandwidth (%#02x) not supported\n", dp_bw);
> +		return -EINVAL;
> +	}
> +
> +	err = anx6345_set_bits(anx6345->map[I2C_IDX_TXCOM], SP_VID_CTRL1_REG,
> +			       SP_VIDEO_MUTE);
> +	if (err)
> +		return err;
> +
> +	err = anx6345_clear_bits(anx6345->map[I2C_IDX_TXCOM],
> +				 SP_VID_CTRL1_REG, SP_VIDEO_EN);
> +	if (err)
> +		return err;
> +
> +	/* Get DPCD info */
> +	err = drm_dp_dpcd_read(&anx6345->aux, DP_DPCD_REV,
> +			       &anx6345->dpcd, DP_RECEIVER_CAP_SIZE);
> +	if (err < 0) {
> +		DRM_ERROR("Failed to read DPCD: %d\n", err);
> +		return err;
> +	}
> +
> +	/* Clear channel x SERDES power down */
> +	err = anx6345_clear_bits(anx6345->map[I2C_IDX_DPTX],
> +				 SP_DP_ANALOG_POWER_DOWN_REG, SP_CH0_PD);
> +	if (err)
> +		return err;
> +
> +	/* Check link capabilities */
> +	err = drm_dp_link_probe(&anx6345->aux, &anx6345->link);
> +	if (err < 0) {
> +		DRM_ERROR("Failed to probe link capabilities: %d\n", err);
> +		return err;
> +	}
> +
> +	/* Power up the sink */
> +	err = drm_dp_link_power_up(&anx6345->aux, &anx6345->link);
> +	if (err < 0) {
> +		DRM_ERROR("Failed to power up DisplayPort link: %d\n", err);
> +		return err;
> +	}
> +
> +	/* Possibly enable downspread on the sink */
> +	err = regmap_write(anx6345->map[I2C_IDX_DPTX],
> +			   SP_DP_DOWNSPREAD_CTRL1_REG, 0);
> +	if (err)
> +		return err;
> +
> +	if (anx6345->dpcd[DP_MAX_DOWNSPREAD] & DP_MAX_DOWNSPREAD_0_5) {
> +		DRM_DEBUG("Enable downspread on the sink\n");
> +		/* 4000PPM */
> +		err = regmap_write(anx6345->map[I2C_IDX_DPTX],
> +				   SP_DP_DOWNSPREAD_CTRL1_REG, 8);
> +		if (err)
> +			return err;
> +
> +		err = drm_dp_dpcd_writeb(&anx6345->aux, DP_DOWNSPREAD_CTRL,
> +					 DP_SPREAD_AMP_0_5);
> +		if (err < 0)
> +			return err;
> +	} else {
> +		err = drm_dp_dpcd_writeb(&anx6345->aux, DP_DOWNSPREAD_CTRL, 0);
> +		if (err < 0)
> +			return err;
> +	}
> +
> +	/* Set the lane count and the link rate on the sink */
> +	if (drm_dp_enhanced_frame_cap(anx6345->dpcd))
> +		err = anx6345_set_bits(anx6345->map[I2C_IDX_DPTX],
> +				       SP_DP_SYSTEM_CTRL_BASE + 4,
> +				       SP_ENHANCED_MODE);
> +	else
> +		err = anx6345_clear_bits(anx6345->map[I2C_IDX_DPTX],
> +					 SP_DP_SYSTEM_CTRL_BASE + 4,
> +					 SP_ENHANCED_MODE);
> +	if (err)
> +		return err;
> +
> +	value = drm_dp_link_rate_to_bw_code(anx6345->link.rate);
> +	err = regmap_write(anx6345->map[I2C_IDX_DPTX],
> +			   SP_DP_MAIN_LINK_BW_SET_REG, value);
> +	if (err)
> +		return err;
> +
> +	err = regmap_write(anx6345->map[I2C_IDX_DPTX],
> +			   SP_DP_LANE_COUNT_SET_REG, anx6345->link.num_lanes);
> +	if (err)
> +		return err;
> +
> +	err = drm_dp_link_configure(&anx6345->aux, &anx6345->link);
> +	if (err < 0) {
> +		DRM_ERROR("Failed to configure DisplayPort link: %d\n", err);
> +		return err;
> +	}
> +
> +	/* Start training on the source */
> +	err = regmap_write(anx6345->map[I2C_IDX_DPTX], SP_DP_LT_CTRL_REG,
> +			   SP_LT_EN);
> +	if (err)
> +		return err;
> +
> +	err = regmap_read_poll_timeout(anx6345->map[I2C_IDX_DPTX],
> +				       SP_DP_LT_CTRL_REG,
> +				       value, !(value & SP_DP_LT_INPROGRESS),
> +				       POLL_DELAY, POLL_TIMEOUT);
> +	if (err)
> +		return err;
> +
> +	return 0;
> +}
> +
> +static int anx6345_tx_initialization(struct anx6345 *anx6345)
> +{
> +	int err, i;
> +
> +	/* FIXME: hardcode color depth now */
> +	err = regmap_write(anx6345->map[I2C_IDX_TXCOM], SP_VID_CTRL2_REG,
> +			   SP_IN_BPC_6BIT << SP_IN_BPC_SHIFT);
> +	if (err)
> +		return err;
> +
> +	err = regmap_write(anx6345->map[I2C_IDX_DPTX], SP_DP_PLL_CTRL_REG, 0);
> +	if (err)
> +		return err;
> +
> +	err = regmap_write(anx6345->map[I2C_IDX_TXCOM],
> +			   SP_ANALOG_DEBUG1_REG, 0);
> +	if (err)
> +		return err;
> +
> +	err = regmap_write(anx6345->map[I2C_IDX_DPTX],
> +			   SP_DP_LINK_DEBUG_CTRL_REG,
> +			   SP_NEW_PRBS7 | SP_M_VID_DEBUG);
> +	if (err)
> +		return err;
> +
> +	err = regmap_write(anx6345->map[I2C_IDX_DPTX],
> +			   SP_DP_ANALOG_POWER_DOWN_REG, 0);
> +	if (err)
> +		return err;
> +
> +	/* Force HPD */
> +	err = anx6345_set_bits(anx6345->map[I2C_IDX_DPTX],
> +			       SP_DP_SYSTEM_CTRL_BASE + 3,
> +			       SP_HPD_FORCE | SP_HPD_CTRL);
> +	if (err)
> +		return err;
> +
> +	for (i = 0; i < 4; i++) {
> +		/* 4 lanes */
> +		err = regmap_write(anx6345->map[I2C_IDX_DPTX],
> +				   SP_DP_LANE0_LT_CTRL_REG + i, 0);
> +		if (err)
> +			return err;
> +	}
> +
> +	/* Reset AUX */
> +	err = anx6345_set_bits(anx6345->map[I2C_IDX_TXCOM],
> +			       SP_RESET_CTRL2_REG, SP_AUX_RST);
> +	if (err)
> +		return err;
> +
> +	err = anx6345_clear_bits(anx6345->map[I2C_IDX_TXCOM],
> +				 SP_RESET_CTRL2_REG, SP_AUX_RST);
> +	if (err)
> +		return err;
> +
> +	return 0;
> +}
> +
> +static void anx6345_poweron(struct anx6345 *anx6345)
> +{
> +	int err;
> +
> +	/* Ensure reset is asserted before starting power on sequence */
> +	gpiod_set_value_cansleep(anx6345->gpiod_reset, 1);
> +	usleep_range(1000, 2000);
> +
> +	err = regulator_enable(anx6345->dvdd12);
> +	if (err) {
> +		DRM_ERROR("Failed to enable DVDD12 regulator: %d\n",
> +			  err);
> +		return;
> +	}
> +
> +	/* T1 - delay between VDD12 and VDD25 should be 0-2ms */
> +	usleep_range(1000, 2000);
> +
> +	err = regulator_enable(anx6345->dvdd25);
> +	if (err) {
> +		DRM_ERROR("Failed to enable DVDD25 regulator: %d\n",
> +			  err);
> +		return;
> +	}
> +
> +	/* T2 - delay between RESETN and all power rail stable,
> +	 * should be 2-5ms
> +	 */
> +	usleep_range(2000, 5000);
> +
> +	gpiod_set_value_cansleep(anx6345->gpiod_reset, 0);
> +
> +	/* Power on registers module */
> +	anx6345_set_bits(anx6345->map[I2C_IDX_TXCOM], SP_POWERDOWN_CTRL_REG,
> +			 SP_HDCP_PD | SP_AUDIO_PD | SP_VIDEO_PD | SP_LINK_PD);
> +	anx6345_clear_bits(anx6345->map[I2C_IDX_TXCOM], SP_POWERDOWN_CTRL_REG,
> +			   SP_REGISTER_PD | SP_TOTAL_PD);
> +
> +	if (anx6345->panel)
> +		drm_panel_prepare(anx6345->panel);
> +
> +	anx6345->powered = true;
> +}
> +
> +static void anx6345_poweroff(struct anx6345 *anx6345)
> +{
> +	int err;
> +
> +	gpiod_set_value_cansleep(anx6345->gpiod_reset, 1);
> +	usleep_range(1000, 2000);
> +
> +	if (anx6345->panel)
> +		drm_panel_unprepare(anx6345->panel);
> +
> +	err = regulator_disable(anx6345->dvdd25);
> +	if (err) {
> +		DRM_ERROR("Failed to disable DVDD25 regulator: %d\n",
> +			  err);
> +		return;
> +	}
> +
> +	usleep_range(5000, 10000);
> +
> +	err = regulator_disable(anx6345->dvdd12);
> +	if (err) {
> +		DRM_ERROR("Failed to disable DVDD12 regulator: %d\n",
> +			  err);
> +		return;
> +	}
> +
> +	usleep_range(1000, 2000);
> +
> +	anx6345->powered = false;
> +}
> +
> +static int anx6345_start(struct anx6345 *anx6345)
> +{
> +	int err;
> +
> +	if (!anx6345->powered)
> +		anx6345_poweron(anx6345);
> +
> +	/* Power on needed modules */
> +	err = anx6345_clear_bits(anx6345->map[I2C_IDX_TXCOM],
> +				SP_POWERDOWN_CTRL_REG,
> +				SP_VIDEO_PD | SP_LINK_PD);
> +
> +	err = anx6345_tx_initialization(anx6345);
> +	if (err) {
> +		DRM_ERROR("Failed DisplayPort transmitter initialization: %d\n", err);
> +		anx6345_poweroff(anx6345);
> +		return err;
> +	}
> +
> +	err = anx6345_dp_link_training(anx6345);
> +	if (err) {
> +		DRM_ERROR("Failed link training: %d\n", err);
> +		anx6345_poweroff(anx6345);
> +		return err;
> +	}
> +
> +	/*
> +	 * This delay seems to help keep the hardware in a good state. Without
> +	 * it, there are times where it fails silently.
> +	 */
> +	usleep_range(10000, 15000);
> +
> +	return 0;
> +}
> +
> +static int anx6345_config_dp_output(struct anx6345 *anx6345)
> +{
> +	int err;
> +
> +	err = anx6345_clear_bits(anx6345->map[I2C_IDX_TXCOM], SP_VID_CTRL1_REG,
> +				 SP_VIDEO_MUTE);
> +	if (err)
> +		return err;
> +
> +	/* Enable DP output */
> +	err = anx6345_set_bits(anx6345->map[I2C_IDX_TXCOM], SP_VID_CTRL1_REG,
> +			       SP_VIDEO_EN);
> +	if (err)
> +		return err;
> +
> +	/* Force stream valid */
> +	err = anx6345_set_bits(anx6345->map[I2C_IDX_DPTX],
> +			       SP_DP_SYSTEM_CTRL_BASE + 3,
> +			       SP_STRM_FORCE | SP_STRM_CTRL);
> +	if (err)
> +		return err;
> +
> +	return 0;
> +}
> +
> +static int anx6345_get_downstream_info(struct anx6345 *anx6345)
> +{
> +	u8 value;
> +	int err;
> +
> +	err = drm_dp_dpcd_readb(&anx6345->aux, DP_SINK_COUNT, &value);
> +	if (err < 0) {
> +		DRM_ERROR("Get sink count failed %d\n", err);
> +		return err;
> +	}
> +
> +	if (!DP_GET_SINK_COUNT(value)) {
> +		DRM_ERROR("Downstream disconnected\n");
> +		return -EIO;
> +	}
> +
> +	return 0;
> +}
> +
> +static int anx6345_get_modes(struct drm_connector *connector)
> +{
> +	struct anx6345 *anx6345 = connector_to_anx6345(connector);
> +	int err, num_modes = 0;
> +	bool power_off = false;
> +
> +	mutex_lock(&anx6345->lock);
> +
> +	if (!anx6345->edid) {

Could the chip be used with a hot-pluggable display, or is it guaranteed
that EDID will never change ?

> +		if (!anx6345->powered) {
> +			anx6345_poweron(anx6345);
> +			power_off = true;
> +		}
> +
> +		err = anx6345_get_downstream_info(anx6345);
> +		if (err) {
> +			DRM_ERROR("Failed to get downstream info: %d\n", err);
> +			goto unlock;
> +		}
> +
> +		anx6345->edid = drm_get_edid(connector, &anx6345->aux.ddc);
> +		if (!anx6345->edid)
> +			DRM_ERROR("Failed to read EDID from panel\n");
> +
> +		err = drm_connector_update_edid_property(connector,
> +							 anx6345->edid);
> +		if (err) {
> +			DRM_ERROR("Failed to update EDID property: %d\n", err);
> +			goto unlock;
> +		}
> +	}
> +
> +	num_modes += drm_add_edid_modes(connector, anx6345->edid);
> +
> +unlock:
> +	if (power_off)
> +		anx6345_poweroff(anx6345);
> +
> +	mutex_unlock(&anx6345->lock);
> +
> +	if (!num_modes && anx6345->panel)
> +		num_modes += drm_panel_get_modes(anx6345->panel);
> +
> +	return num_modes;
> +}
> +
> +static const struct drm_connector_helper_funcs anx6345_connector_helper_funcs = {
> +	.get_modes = anx6345_get_modes,
> +};
> +
> +static void
> +anx6345_connector_destroy(struct drm_connector *connector)
> +{
> +	struct anx6345 *anx6345 = connector_to_anx6345(connector);
> +
> +	if (anx6345->panel)
> +		drm_panel_detach(anx6345->panel);
> +	drm_connector_cleanup(connector);
> +}
> +
> +static const struct drm_connector_funcs anx6345_connector_funcs = {
> +	.fill_modes = drm_helper_probe_single_connector_modes,
> +	.destroy = anx6345_connector_destroy,
> +	.reset = drm_atomic_helper_connector_reset,
> +	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
> +	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
> +};
> +
> +static int anx6345_bridge_attach(struct drm_bridge *bridge)
> +{
> +	struct anx6345 *anx6345 = bridge_to_anx6345(bridge);
> +	int err;
> +
> +	if (!bridge->encoder) {
> +		DRM_ERROR("Parent encoder object not found");
> +		return -ENODEV;
> +	}
> +
> +	/* Register aux channel */
> +	anx6345->aux.name = "DP-AUX";
> +	anx6345->aux.dev = &anx6345->client->dev;
> +	anx6345->aux.transfer = anx6345_aux_transfer;
> +
> +	err = drm_dp_aux_register(&anx6345->aux);
> +	if (err < 0) {
> +		DRM_ERROR("Failed to register aux channel: %d\n", err);
> +		return err;
> +	}
> +
> +	err = drm_connector_init(bridge->dev, &anx6345->connector,
> +				 &anx6345_connector_funcs,
> +				 DRM_MODE_CONNECTOR_eDP);
> +	if (err) {
> +		DRM_ERROR("Failed to initialize connector: %d\n", err);
> +		return err;
> +	}
> +
> +	drm_connector_helper_add(&anx6345->connector,
> +				 &anx6345_connector_helper_funcs);
> +
> +	err = drm_connector_register(&anx6345->connector);
> +	if (err) {
> +		DRM_ERROR("Failed to register connector: %d\n", err);
> +		return err;
> +	}
> +
> +	anx6345->connector.polled = DRM_CONNECTOR_POLL_HPD;
> +
> +	err = drm_connector_attach_encoder(&anx6345->connector,
> +					   bridge->encoder);
> +	if (err) {
> +		DRM_ERROR("Failed to link up connector to encoder: %d\n", err);
> +		return err;
> +	}
> +
> +	if (anx6345->panel) {
> +		err = drm_panel_attach(anx6345->panel, &anx6345->connector);
> +		if (err) {
> +			DRM_ERROR("Failed to attach panel: %d\n", err);
> +			return err;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static enum drm_mode_status
> +anx6345_bridge_mode_valid(struct drm_bridge *bridge,
> +			  const struct drm_display_mode *mode)
> +{
> +	if (mode->flags & DRM_MODE_FLAG_INTERLACE)
> +		return MODE_NO_INTERLACE;
> +
> +	/* Max 1200p at 5.4 Ghz, one lane */
> +	if (mode->clock > 154000)
> +		return MODE_CLOCK_HIGH;
> +
> +	return MODE_OK;
> +}
> +
> +static void anx6345_bridge_disable(struct drm_bridge *bridge)
> +{
> +	struct anx6345 *anx6345 = bridge_to_anx6345(bridge);
> +
> +	/* Power off all modules except configuration registers access */
> +	anx6345_set_bits(anx6345->map[I2C_IDX_TXCOM], SP_POWERDOWN_CTRL_REG,
> +			 SP_HDCP_PD | SP_AUDIO_PD | SP_VIDEO_PD | SP_LINK_PD);
> +	if (anx6345->panel)
> +		drm_panel_disable(anx6345->panel);

How about using the drm_panel_bridge infrastructure ? It would be easier
than handling the panel manually, as the bridge core will do it for you.

> +
> +	if (anx6345->powered)
> +		anx6345_poweroff(anx6345);
> +}
> +
> +static void anx6345_bridge_enable(struct drm_bridge *bridge)
> +{
> +	struct anx6345 *anx6345 = bridge_to_anx6345(bridge);
> +	int err;
> +
> +	if (anx6345->panel)
> +		drm_panel_enable(anx6345->panel);
> +
> +	err = anx6345_start(anx6345);
> +	if (err) {
> +		DRM_ERROR("Failed to initialize: %d\n", err);
> +		return;
> +	}
> +
> +	err = anx6345_config_dp_output(anx6345);
> +	if (err)
> +		DRM_ERROR("Failed to enable DP output: %d\n", err);
> +}
> +
> +static const struct drm_bridge_funcs anx6345_bridge_funcs = {
> +	.attach = anx6345_bridge_attach,
> +	.mode_valid = anx6345_bridge_mode_valid,
> +	.disable = anx6345_bridge_disable,
> +	.enable = anx6345_bridge_enable,
> +};
> +
> +static void unregister_i2c_dummy_clients(struct anx6345 *anx6345)
> +{
> +	unsigned int i;
> +
> +	for (i = 1; i < ARRAY_SIZE(anx6345->i2c_clients); i++)
> +		if (anx6345->i2c_clients[i] &&
> +		    anx6345->i2c_clients[i]->addr != anx6345->client->addr)
> +			i2c_unregister_device(anx6345->i2c_clients[i]);
> +}
> +
> +static const struct regmap_config anx6345_regmap_config = {
> +	.reg_bits = 8,
> +	.val_bits = 8,
> +	.max_register = 0xff,
> +	.cache_type = REGCACHE_NONE,
> +};
> +
> +static const u16 anx6345_chipid_list[] = {
> +	0x6345,
> +};
> +
> +static int anx6345_i2c_probe(struct i2c_client *client,
> +			     const struct i2c_device_id *id)
> +{
> +	struct anx6345 *anx6345;
> +	struct device *dev;
> +	unsigned int i, idl, idh, version;
> +	bool found = false;
> +	int err;
> +
> +	anx6345 = devm_kzalloc(&client->dev, sizeof(*anx6345), GFP_KERNEL);
> +	if (!anx6345)
> +		return -ENOMEM;
> +
> +	mutex_init(&anx6345->lock);
> +
> +	anx6345->bridge.of_node = client->dev.of_node;
> +
> +	anx6345->client = client;
> +	i2c_set_clientdata(client, anx6345);
> +
> +	dev = &anx6345->client->dev;
> +
> +	err = drm_of_find_panel_or_bridge(client->dev.of_node, 1, 0,
> +					  &anx6345->panel, NULL);
> +	if (err == -EPROBE_DEFER)
> +		return err;
> +
> +	if (err)
> +		DRM_DEBUG("No panel found\n");

Shouldn't this be fatal ?

> +
> +	/* 1.2V digital core power regulator  */
> +	anx6345->dvdd12 = devm_regulator_get(dev, "dvdd12-supply");
> +	if (IS_ERR(anx6345->dvdd12)) {
> +		DRM_ERROR("DVDD12 regulator not found\n");
> +		return PTR_ERR(anx6345->dvdd12);
> +	}
> +
> +	/* 2.5V digital core power regulator  */
> +	anx6345->dvdd25 = devm_regulator_get(dev, "dvdd25-supply");
> +	if (IS_ERR(anx6345->dvdd25)) {
> +		DRM_ERROR("DVDD25 regulator not found\n");
> +		return PTR_ERR(anx6345->dvdd25);
> +	}
> +
> +	/* GPIO for chip reset */
> +	anx6345->gpiod_reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
> +	if (IS_ERR(anx6345->gpiod_reset)) {
> +		DRM_ERROR("Reset gpio not found\n");
> +		return PTR_ERR(anx6345->gpiod_reset);
> +	}
> +
> +	/* Map slave addresses of ANX6345 */
> +	for (i = 0; i < I2C_NUM_ADDRESSES; i++) {
> +		if (anx6345_i2c_addresses[i] >> 1 != client->addr)
> +			anx6345->i2c_clients[i] = i2c_new_dummy(client->adapter,
> +						anx6345_i2c_addresses[i] >> 1);
> +		else
> +			anx6345->i2c_clients[i] = client;
> +
> +		if (!anx6345->i2c_clients[i]) {
> +			err = -ENOMEM;
> +			DRM_ERROR("Failed to reserve I2C bus %02x\n",
> +				  anx6345_i2c_addresses[i]);
> +			goto err_unregister_i2c;
> +		}
> +
> +		anx6345->map[i] = devm_regmap_init_i2c(anx6345->i2c_clients[i],
> +						       &anx6345_regmap_config);
> +		if (IS_ERR(anx6345->map[i])) {
> +			err = PTR_ERR(anx6345->map[i]);
> +			DRM_ERROR("Failed regmap initialization %02x\n",
> +				  anx6345_i2c_addresses[i]);
> +			goto err_unregister_i2c;
> +		}
> +	}
> +
> +	/* Look for supported chip ID */
> +	anx6345_poweron(anx6345);
> +
> +	err = regmap_read(anx6345->map[I2C_IDX_TXCOM], SP_DEVICE_IDL_REG,
> +			  &idl);
> +	if (err)
> +		goto err_poweroff;
> +
> +	err = regmap_read(anx6345->map[I2C_IDX_TXCOM], SP_DEVICE_IDH_REG,
> +			  &idh);
> +	if (err)
> +		goto err_poweroff;
> +
> +	anx6345->chipid = (u8)idl | ((u8)idh << 8);
> +
> +	err = regmap_read(anx6345->map[I2C_IDX_TXCOM], SP_DEVICE_VERSION_REG,
> +			  &version);
> +	if (err)
> +		goto err_poweroff;
> +
> +	for (i = 0; i < ARRAY_SIZE(anx6345_chipid_list); i++) {
> +		if (anx6345->chipid == anx6345_chipid_list[i]) {
> +			DRM_INFO("Found ANX%x (ver. %d) eDP Transmitter\n",
> +				 anx6345->chipid, version);
> +			found = true;
> +			break;
> +		}
> +	}
> +
> +	if (!found) {
> +		DRM_ERROR("ANX%x (ver. %d) not supported by this driver\n",
> +			  anx6345->chipid, version);
> +		err = -ENODEV;
> +		goto err_poweroff;
> +	}

If you moved the chip detection code to a separate function, you could
write this

	anx6345_poweron(anx6345);
	ret = anx6345_detect(anx6345);
	anx6345_poweroff(anx6345);

	if (ret < 0) {
		...
	}

and remove the power off error label. Up to you.

> +
> +	anx6345->bridge.funcs = &anx6345_bridge_funcs;
> +
> +	drm_bridge_add(&anx6345->bridge);
> +
> +	anx6345_poweroff(anx6345);
> +
> +	return 0;
> +
> +err_poweroff:
> +	anx6345_poweroff(anx6345);
> +
> +err_unregister_i2c:
> +	unregister_i2c_dummy_clients(anx6345);
> +	return err;
> +}
> +
> +static int anx6345_i2c_remove(struct i2c_client *client)
> +{
> +	struct anx6345 *anx6345 = i2c_get_clientdata(client);
> +
> +	drm_bridge_remove(&anx6345->bridge);
> +
> +	unregister_i2c_dummy_clients(anx6345);
> +
> +	kfree(anx6345->edid);

	mutex_cleanup(&anx6345->lock);

> +
> +	return 0;
> +}
> +
> +static const struct i2c_device_id anx6345_id[] = {
> +	{ "anx6345", 0 },
> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(i2c, anx6345_id);
> +
> +static const struct of_device_id anx6345_match_table[] = {
> +	{ .compatible = "analogix,anx6345", },
> +	{ /* sentinel */ },
> +};
> +MODULE_DEVICE_TABLE(of, anx6345_match_table);
> +
> +static struct i2c_driver anx6345_driver = {
> +	.driver = {
> +		   .name = "anx6345",
> +		   .of_match_table = of_match_ptr(anx6345_match_table),
> +		  },
> +	.probe = anx6345_i2c_probe,
> +	.remove = anx6345_i2c_remove,
> +	.id_table = anx6345_id,
> +};
> +module_i2c_driver(anx6345_driver);
> +
> +MODULE_DESCRIPTION("ANX6345 eDP Transmitter driver");
> +MODULE_AUTHOR("Icenowy Zheng <icenowy@aosc.io>");
> +MODULE_LICENSE("GPL v2");
> diff --git a/drivers/gpu/drm/bridge/analogix/analogix-i2c-dptx.c b/drivers/gpu/drm/bridge/analogix/analogix-i2c-dptx.c
> index 9cb30962032e..53b0e73d6a24 100644
> --- a/drivers/gpu/drm/bridge/analogix/analogix-i2c-dptx.c
> +++ b/drivers/gpu/drm/bridge/analogix/analogix-i2c-dptx.c
> @@ -117,7 +117,7 @@ ssize_t anx_aux_transfer(struct regmap *map_dptx, struct drm_dp_aux_msg *msg)
>  	else	/* For non-zero-sized set the length field. */
>  		ctrl1 |= (msg->size - 1) << SP_AUX_LENGTH_SHIFT;
>  
> -	if ((msg->request & DP_AUX_I2C_READ) == 0) {
> +	if ((msg->size > 0) && ((msg->request & DP_AUX_I2C_READ) == 0)) {
>  		/* When WRITE | MOT write values to data buffer */
>  		err = regmap_bulk_write(map_dptx,
>  					SP_DP_BUF_DATA0_REG, buffer,

This and the changes below should be split to a separate patch.

> diff --git a/drivers/gpu/drm/bridge/analogix/analogix-i2c-dptx.h b/drivers/gpu/drm/bridge/analogix/analogix-i2c-dptx.h
> index c2ca854613a0..b29a0b3bc23c 100644
> --- a/drivers/gpu/drm/bridge/analogix/analogix-i2c-dptx.h
> +++ b/drivers/gpu/drm/bridge/analogix/analogix-i2c-dptx.h
> @@ -75,7 +75,11 @@
>  #define SP_CHA_STA			BIT(2)
>  /* Bits for DP System Control Register 3 */
>  #define SP_HPD_STATUS			BIT(6)
> +#define SP_HPD_FORCE			BIT(5)
> +#define SP_HPD_CTRL			BIT(4)
>  #define SP_STRM_VALID			BIT(2)
> +#define SP_STRM_FORCE			BIT(1)
> +#define SP_STRM_CTRL			BIT(0)
>  /* Bits for DP System Control Register 4 */
>  #define SP_ENHANCED_MODE		BIT(3)
>  
> @@ -120,6 +124,9 @@
>  #define SP_LINK_BW_SET_MASK		0x1f
>  #define SP_INITIAL_SLIM_M_AUD_SEL	BIT(5)
>  
> +/* DP Lane Count Setting Register */
> +#define SP_DP_LANE_COUNT_SET_REG	0xa1
> +
>  /* DP Training Pattern Set Register */
>  #define SP_DP_TRAINING_PATTERN_SET_REG	0xa2
>  
> @@ -133,6 +140,7 @@
>  
>  /* DP Link Training Control Register */
>  #define SP_DP_LT_CTRL_REG		0xa8
> +#define SP_DP_LT_INPROGRESS		0x80
>  #define SP_LT_ERROR_TYPE_MASK		0x70
>  #  define SP_LT_NO_ERROR		0x00
>  #  define SP_LT_AUX_WRITE_ERROR		0x01
> diff --git a/drivers/gpu/drm/bridge/analogix/analogix-i2c-txcommon.h b/drivers/gpu/drm/bridge/analogix/analogix-i2c-txcommon.h
> index 7d683573e970..480c98a225b1 100644
> --- a/drivers/gpu/drm/bridge/analogix/analogix-i2c-txcommon.h
> +++ b/drivers/gpu/drm/bridge/analogix/analogix-i2c-txcommon.h
> @@ -183,6 +183,9 @@
>  #define SP_VBIT				BIT(1)
>  #define SP_AUDIO_LAYOUT			BIT(0)
>  
> +/* Analog Debug Register 1 */
> +#define SP_ANALOG_DEBUG1_REG		0xdc
> +
>  /* Analog Debug Register 2 */
>  #define SP_ANALOG_DEBUG2_REG		0xdd
>  #define SP_FORCE_SW_OFF_BYPASS		0x20

-- 
Regards,

Laurent Pinchart