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Date:   Mon, 23 Sep 2019 17:03:55 +0300
From:   Dan Carpenter <dan.carpenter@oracle.com>
To:     Xin Ji <xji@analogixsemi.com>
Cc:     "devel@driverdev.osuosl.org" <devel@driverdev.osuosl.org>,
        Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        Andrzej Hajda <a.hajda@samsung.com>,
        Jernej Skrabec <jernej.skrabec@siol.net>,
        Jonas Karlman <jonas@kwiboo.se>,
        David Airlie <airlied@linux.ie>,
        Neil Armstrong <narmstrong@baylibre.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "dri-devel@lists.freedesktop.org" <dri-devel@lists.freedesktop.org>,
        Sheng Pan <span@analogixsemi.com>,
        Daniel Vetter <daniel@ffwll.ch>
Subject: Re: [PATCH v1 2/2] drm/bridge: anx7625: Add anx7625 MIPI to DP
 bridge driver
Message-ID: <20190923140355.GH2959@kadam>
References: <cover.1568957788.git.xji@analogixsemi.com>
 <02319a7db948900efe0f945b684221ac076bac48.1568957789.git.xji@analogixsemi.com>
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I wish you would think more about the error codes that you're returning.
Most functions do "ret |= frob()." which ORs the error codes together,
and results in a nonsense negative error code.  But then some functions
return 1 on error and zero on success which is sometimes a bug,
sometimes confusing but always ugly.

On Fri, Sep 20, 2019 at 06:07:43AM +0000, Xin Ji wrote:
> The ANX7625 is an ultra-low power 4K Mobile HD Transmitter designed
> for portable device. It converts MIPI to DisplayPort 1.3 4K.
> 
> Signed-off-by: Xin Ji <xji@analogixsemi.com>
> ---
>  drivers/gpu/drm/bridge/Makefile           |    2 +-
>  drivers/gpu/drm/bridge/analogix/Kconfig   |    6 +
>  drivers/gpu/drm/bridge/analogix/Makefile  |    1 +
>  drivers/gpu/drm/bridge/analogix/anx7625.c | 2085 +++++++++++++++++++++++++++++
>  drivers/gpu/drm/bridge/analogix/anx7625.h |  397 ++++++
>  5 files changed, 2490 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/gpu/drm/bridge/analogix/anx7625.c
>  create mode 100644 drivers/gpu/drm/bridge/analogix/anx7625.h
> 
> diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
> index 4934fcf..bcd388a 100644
> --- a/drivers/gpu/drm/bridge/Makefile
> +++ b/drivers/gpu/drm/bridge/Makefile
> @@ -12,8 +12,8 @@ obj-$(CONFIG_DRM_SII9234) += sii9234.o
>  obj-$(CONFIG_DRM_THINE_THC63LVD1024) += thc63lvd1024.o
>  obj-$(CONFIG_DRM_TOSHIBA_TC358764) += tc358764.o
>  obj-$(CONFIG_DRM_TOSHIBA_TC358767) += tc358767.o
> -obj-$(CONFIG_DRM_ANALOGIX_DP) += analogix/
>  obj-$(CONFIG_DRM_I2C_ADV7511) += adv7511/
>  obj-$(CONFIG_DRM_TI_SN65DSI86) += ti-sn65dsi86.o
>  obj-$(CONFIG_DRM_TI_TFP410) += ti-tfp410.o
> +obj-y += analogix/
>  obj-y += synopsys/
> diff --git a/drivers/gpu/drm/bridge/analogix/Kconfig b/drivers/gpu/drm/bridge/analogix/Kconfig
> index e930ff9..b2f127e 100644
> --- a/drivers/gpu/drm/bridge/analogix/Kconfig
> +++ b/drivers/gpu/drm/bridge/analogix/Kconfig
> @@ -2,3 +2,9 @@
>  config DRM_ANALOGIX_DP
>  	tristate
>  	depends on DRM
> +
> +config ANALOGIX_ANX7625
> +	tristate "Analogix MIPI to DP interface support"
> +	help
> +		ANX7625 is an ultra-low power 4K mobile HD transmitter designed
> +		for portable devices. It converts MIPI/DPI to DisplayPort1.3 4K.
> diff --git a/drivers/gpu/drm/bridge/analogix/Makefile b/drivers/gpu/drm/bridge/analogix/Makefile
> index fdbf3fd..8a52867 100644
> --- a/drivers/gpu/drm/bridge/analogix/Makefile
> +++ b/drivers/gpu/drm/bridge/analogix/Makefile
> @@ -1,3 +1,4 @@
>  # SPDX-License-Identifier: GPL-2.0-only
> +obj-$(CONFIG_ANALOGIX_ANX7625) += anx7625.o
>  analogix_dp-objs := analogix_dp_core.o analogix_dp_reg.o
>  obj-$(CONFIG_DRM_ANALOGIX_DP) += analogix_dp.o
> diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.c b/drivers/gpu/drm/bridge/analogix/anx7625.c
> new file mode 100644
> index 0000000..eceadef
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/analogix/anx7625.c
> @@ -0,0 +1,2085 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright(c) 2016, Analogix Semiconductor. All rights reserved.
> + *
> + */
> +#include <linux/extcon.h>
> +#include <linux/gcd.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/i2c.h>
> +#include <linux/interrupt.h>
> +#include <linux/iopoll.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/slab.h>
> +#include <linux/types.h>
> +#include <linux/workqueue.h>
> +
> +#include <linux/of_gpio.h>
> +#include <linux/of_graph.h>
> +#include <linux/of_platform.h>
> +
> +#include <drm/drm_atomic_helper.h>
> +#include <drm/drm_bridge.h>
> +#include <drm/drm_crtc_helper.h>
> +#include <drm/drm_dp_helper.h>
> +#include <drm/drm_edid.h>
> +#include <drm/drm_mipi_dsi.h>
> +#include <drm/drm_print.h>
> +#include <drm/drm_probe_helper.h>
> +
> +#include <video/display_timing.h>
> +
> +#include "anx7625.h"
> +
> +/*
> + * there is a sync issue while access I2C register between AP(CPU) and
> + * internal firmware(OCM), to avoid the race condition, AP should access
> + * the reserved slave address before slave address occurs changes.
> + */
> +static int i2c_access_workaround(struct anx7625_data *ctx,
> +				 struct i2c_client *client)
> +{
> +	u8 offset;
> +	struct device *dev = &client->dev;
> +	struct i2c_client *last_client = ctx->last_client;
> +	int ret = 0;
> +
> +	if (client != last_client) {

Flip this around:

	if (client == last_client)
		return 0;

> +		ctx->last_client = client;
> +
> +		if (client == ctx->i2c.tcpc_client)
> +			offset = RSVD_00_ADDR;
> +		else if (client == ctx->i2c.tx_p0_client)
> +			offset = RSVD_D1_ADDR;
> +		else if (client == ctx->i2c.tx_p1_client)
> +			offset = RSVD_60_ADDR;
> +		else if (client == ctx->i2c.rx_p0_client)
> +			offset = RSVD_39_ADDR;
> +		else if (client == ctx->i2c.rx_p1_client)
> +			offset = RSVD_7F_ADDR;
> +		else
> +			offset = RSVD_00_ADDR;
> +
> +		ret = i2c_smbus_write_byte_data(client, offset, 0x00);
> +		if (ret < 0)
> +			DRM_DEV_ERROR(dev,
> +				      "failed to access i2c id=%x\n:%x",
> +				      client->addr, offset);
> +	}
> +
> +	return ret;
> +}
> +
> +static int anx7625_reg_read(struct anx7625_data *ctx,
> +			    struct i2c_client *client, u8 reg_addr)
> +{
> +	int ret;
> +	struct device *dev = &client->dev;
> +
> +	i2c_access_workaround(ctx, client);
> +
> +	ret = i2c_smbus_read_byte_data(client, reg_addr);
> +	if (ret < 0)
> +		DRM_DEV_ERROR(dev, "read i2c failed id=%x:%x\n",
> +			      client->addr, reg_addr);
> +
> +	return ret;
> +}
> +
> +static int anx7625_reg_block_read(struct anx7625_data *ctx,
> +				  struct i2c_client *client,
> +				  u8 reg_addr, u8 len, u8 *buf)
> +{
> +	int ret;
> +	struct device *dev = &client->dev;
> +
> +	i2c_access_workaround(ctx, client);
> +
> +	ret = i2c_smbus_read_i2c_block_data(client, reg_addr, len, buf);
> +	if (ret < 0)
> +		DRM_DEV_ERROR(dev, "read i2c block failed id=%x:%x\n",
> +			      client->addr, reg_addr);
> +
> +	return ret;
> +}
> +
> +static int anx7625_reg_write(struct anx7625_data *ctx,
> +			     struct i2c_client *client,
> +			     u8 reg_addr, u8 reg_val)
> +{
> +	int ret;
> +	struct device *dev = &client->dev;
> +
> +	i2c_access_workaround(ctx, client);
> +
> +	ret = i2c_smbus_write_byte_data(client, reg_addr, reg_val);
> +
> +	if (ret < 0)
> +		DRM_DEV_ERROR(dev, "failed to write i2c id=%x\n:%x",
> +			      client->addr, reg_addr);
> +
> +	return ret;
> +}
> +
> +static int anx7625_write_or(struct anx7625_data *ctx,
> +			    struct i2c_client *client,
> +			    u8 offset, u8 mask)
> +{
> +	int val = anx7625_reg_read(ctx, client, offset);
> +
> +	return (val < 0) ? val :
> +		anx7625_reg_write(ctx, client, offset, (val | (mask)));


Write these functions cleaner like this:

	int val;

	val = anx7625_reg_read(ctx, client, offset);
	if (val < 0)
		return val;

	return anx7625_reg_write(ctx, client, offset, (val | (mask)));


> +}
> +
> +static int anx7625_write_and(struct anx7625_data *ctx,
> +			     struct i2c_client *client,
> +			     u8 offset, u8 mask)
> +{
> +	int val = anx7625_reg_read(ctx, client, offset);
> +
> +	return (val < 0) ? val :
> +		anx7625_reg_write(ctx, client, offset, (val & (mask)));
> +}
> +
> +static int anx7625_write_and_or(struct anx7625_data *ctx,
> +				struct i2c_client *client,
> +				u8 offset, u8 and_mask, u8 or_mask)
> +{
> +	int val = anx7625_reg_read(ctx, client, offset);
> +
> +	return (val < 0) ? val :
> +		anx7625_reg_write(ctx, client, offset,
> +				  (val & and_mask) | (or_mask));
> +}
> +
> +static int anx7625_config_bit_matrix(struct anx7625_data *ctx)
> +{
> +	int i, ret;
> +
> +	ret = anx7625_reg_write(ctx, ctx->i2c.tx_p2_client,
> +				AUDIO_CONTROL_REGISTER, 0x80);
> +	for (i = 0; i < 13; i++)
                        ^^
Magic number.


> +		ret |= anx7625_reg_write(ctx, ctx->i2c.tx_p2_client,
> +					 VIDEO_BIT_MATRIX_12 + i,
> +					 0x18 + i);
> +
> +	return ret;
> +}
> +
> +static int anx7625_read_ctrl_status_p0(struct anx7625_data *ctx)
> +{
> +	return anx7625_reg_read(ctx, ctx->i2c.rx_p0_client, AP_AUX_CTRL_STATUS);
> +}
> +
> +static int wait_aux_op_finish(struct anx7625_data *ctx)
> +{
> +	int val;
> +	int ret;
> +	struct device *dev = &ctx->client->dev;
> +
> +	ret = readx_poll_timeout(anx7625_read_ctrl_status_p0,
> +				 ctx, val,
> +				 (!(val & AP_AUX_CTRL_OP_EN) || (val < 0)),
> +				 2000,
> +				 2000 * 150);
> +	if (ret) {
> +		DRM_DEV_ERROR(dev, "aux operation failed!\n");
> +		val = -EIO;

Return directly:

	if (ret) {
		DRM_DEV_ERROR(dev, "aux operation failed!\n");
		return ret;
	}


> +	} else {
> +		val = anx7625_reg_read(ctx, ctx->i2c.rx_p0_client,
> +				       AP_AUX_CTRL_STATUS);
> +		if (val < 0 || (val & 0x0F)) {
> +			DRM_DEV_ERROR(dev, "aux status %02x\n", val);
> +			val = -EIO;
> +		}
> +	}
> +
> +	return val;
> +}
> +
> +static int write_dpcd_addr(struct anx7625_data *ctx,
> +			   u8 addrh, u8 addrm, u8 addrl)
> +{
> +	int ret;
> +
> +	ret = anx7625_reg_write(ctx, ctx->i2c.rx_p0_client,
> +				AP_AUX_ADDR_7_0, (u8)addrl);
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p0_client,
> +				 AP_AUX_ADDR_15_8, (u8)addrm);
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p0_client,
> +				 AP_AUX_ADDR_19_16, (u8)addrh);
> +
> +	return ret;
> +}
> +
> +static int sp_tx_aux_dpcdread_bytes(struct anx7625_data *ctx,
> +				    u8 addrh, u8 addrm,
> +				    u8 addrl, u8 count,
> +				    u8 *buf)
> +{
> +	u8 c;
> +	int ret;
> +	struct device *dev = &ctx->client->dev;
> +
> +	if (WARN_ON(count > (size_t)MAX_DPCD_BUFFER_SIZE))

This cast is not required.

> +		return -E2BIG;
> +
> +	/* command and length */
> +	c = ((count - 1) << 4) | 0x09;
> +	ret = anx7625_reg_write(ctx, ctx->i2c.rx_p0_client, AP_AUX_COMMAND, c);
> +	/* address */
> +	ret |= write_dpcd_addr(ctx, addrh, addrm, addrl);
> +	/* aux en */
> +	ret |= anx7625_write_or(ctx, ctx->i2c.rx_p0_client, AP_AUX_CTRL_STATUS,
> +				AP_AUX_CTRL_OP_EN);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(dev, "aux enable failed.\n");
> +		return ret;
> +	}
> +
> +	usleep_range(2000, 2100);
> +
> +	ret = wait_aux_op_finish(ctx);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(dev, "aux read failed\n");
> +		return ret;
> +	}
> +
> +	return anx7625_reg_block_read(ctx, ctx->i2c.rx_p0_client,
> +			AP_AUX_BUFF_START, count, buf);
> +}
> +
> +static int anx7625_video_mute_control(struct anx7625_data *ctx,
> +				      u8 status)
> +{
> +	int ret;
> +
> +	if (status) { /* mute on */
> +		/* set mute flag */
> +		ret = anx7625_write_or(ctx, ctx->i2c.rx_p0_client,
> +				       AP_AV_STATUS, AP_MIPI_MUTE);
> +		/* clear mipi RX en */
> +		ret |= anx7625_write_and(ctx, ctx->i2c.rx_p0_client,
> +					 AP_AV_STATUS, (u8)~AP_MIPI_RX_EN);
> +	} else { /* mute off */
> +		/* clear mute flag */
> +		ret = anx7625_write_and(ctx, ctx->i2c.rx_p0_client,
> +					AP_AV_STATUS, (u8)~AP_MIPI_MUTE);
> +		/* set MIPI RX EN */
> +		ret |= anx7625_write_or(ctx, ctx->i2c.rx_p0_client,
> +					AP_AV_STATUS, AP_MIPI_RX_EN);
> +	}
> +
> +	return ret;
> +}
> +
> +static int anx7625_config_audio_input(struct anx7625_data *ctx)
> +{
> +	int ret;
> +
> +	/* channel num */
> +	ret = anx7625_reg_write(ctx, ctx->i2c.tx_p2_client,
> +				AUDIO_CHANNEL_STATUS_6, I2S_CH_2 << 5);
> +	/* layout */
> +	/* as I2S channel is 2, no need to set layout */
> +
> +	/* FS */
> +	ret |= anx7625_write_and_or(ctx, ctx->i2c.tx_p2_client,
> +				    AUDIO_CHANNEL_STATUS_4,
> +				    0xf0, AUDIO_FS_48K);
> +	/* word length */
> +	ret |= anx7625_write_and_or(ctx, ctx->i2c.tx_p2_client,
> +				    AUDIO_CHANNEL_STATUS_5,
> +				    0xf0, AUDIO_W_LEN_24_24MAX);
> +	/* I2S */
> +	ret |= anx7625_write_or(ctx, ctx->i2c.tx_p2_client,
> +				AUDIO_CHANNEL_STATUS_6, I2S_SLAVE_MODE);
> +	ret |= anx7625_write_and(ctx, ctx->i2c.tx_p2_client,
> +				 AUDIO_CONTROL_REGISTER, ~TDM_TIMING_MODE);
> +	/* audio change flag */
> +	ret |= anx7625_write_or(ctx, ctx->i2c.rx_p0_client,
> +				AP_AV_STATUS, AP_AUDIO_CHG);
> +
> +	if (ret < 0)
> +		DRM_ERROR("failed to config audio.\n");
> +
> +	return ret;
> +}
> +
> +/* reduction of fraction a/b */
> +static void anx7625_reduction_of_a_fraction(unsigned long *a, unsigned long *b)
> +{
> +	unsigned long gcd_num;
> +	unsigned long tmp_a, tmp_b;
> +	u32 i = 1;
> +
> +	gcd_num = gcd(*a, *b);
> +	*a /= gcd_num;
> +	*b /= gcd_num;
> +
> +	tmp_a = *a;
> +	tmp_b = *b;
> +
> +	while ((*a > MAX_UNSIGNED_24BIT) || (*b > MAX_UNSIGNED_24BIT)) {
> +		i++;
> +		*a = tmp_a / i;
> +		*b = tmp_b / i;
> +	}
> +
> +	/*
> +	 * in the end, make a, b larger to have higher ODFC PLL
> +	 * output frequency accuracy
> +	 */
> +	while ((*a < MAX_UNSIGNED_24BIT) && (*b < MAX_UNSIGNED_24BIT)) {
> +		*a <<= 1;
> +		*b <<= 1;
> +	}
> +
> +	*a >>= 1;
> +	*b >>= 1;
> +}
> +
> +static int anx7625_calculate_m_n(u32 pixelclock,
> +				 unsigned long *m,
> +				 unsigned long *n,
> +				 u8 *post_divider)
> +{
> +	if (pixelclock > PLL_OUT_FREQ_ABS_MAX / POST_DIVIDER_MIN) {
> +		/* pixel clock frequency is too high */
> +		DRM_ERROR("pixelclock too high, act(%d), maximum(%lu)\n",
> +			  pixelclock,
> +			  PLL_OUT_FREQ_ABS_MAX / POST_DIVIDER_MIN);
> +		return 1;

Returning one on error is ugly.  return -EINVAL;

> +	}
> +
> +	if (pixelclock < PLL_OUT_FREQ_ABS_MIN / POST_DIVIDER_MAX) {
> +		/* pixel clock frequency is too low */
> +		DRM_ERROR("pixelclock too low, act(%d), maximum(%lu)\n",
> +			  pixelclock,
> +			  PLL_OUT_FREQ_ABS_MIN / POST_DIVIDER_MAX);
> +		return 1;
> +	}
> +
> +	*post_divider = 1;
> +
> +	for (*post_divider = 1;
> +		pixelclock < (PLL_OUT_FREQ_MIN / (*post_divider));)
> +		*post_divider += 1;
> +
> +	if (*post_divider > POST_DIVIDER_MAX) {
> +		for (*post_divider = 1;
> +			(pixelclock <
> +			 (PLL_OUT_FREQ_ABS_MIN / (*post_divider)));)
> +			*post_divider += 1;
> +
> +		if (*post_divider > POST_DIVIDER_MAX) {
> +			DRM_ERROR("cannot find property post_divider(%d)\n",
> +				  *post_divider);
> +			return 1;
> +		}
> +	}
> +
> +	/* patch to improve the accuracy */
> +	if (*post_divider == 7) {
> +		/* 27,000,000 is not divisible by 7 */
> +		*post_divider = 8;
> +	} else if (*post_divider == 11) {
> +		/* 27,000,000 is not divisible by 11 */
> +		*post_divider = 12;
> +	} else if ((*post_divider == 13) || (*post_divider == 14)) {
> +		/*27,000,000 is not divisible by 13 or 14*/
> +		*post_divider = 15;
> +	}
> +
> +	if (pixelclock * (*post_divider) > PLL_OUT_FREQ_ABS_MAX) {
> +		DRM_ERROR("act clock(%u) large than maximum(%lu)\n",
> +			  pixelclock * (*post_divider),
> +			  PLL_OUT_FREQ_ABS_MAX);
> +		return 1;
> +	}
> +
> +	*m = pixelclock;
> +	*n = XTAL_FRQ / (*post_divider);
> +
> +	anx7625_reduction_of_a_fraction(m, n);
> +
> +	return 0;
> +}
> +
> +static int anx7625_odfc_config(struct anx7625_data *ctx,
> +			       u8 post_divider)
> +{
> +	int ret;
> +
> +	/* config input reference clock frequency 27MHz/19.2MHz */
> +	ret = anx7625_write_and(ctx, ctx->i2c.rx_p1_client, MIPI_DIGITAL_PLL_16,
> +				~(REF_CLK_27000KHZ << MIPI_FREF_D_IND));
> +	ret |= anx7625_write_or(ctx, ctx->i2c.rx_p1_client, MIPI_DIGITAL_PLL_16,
> +				(REF_CLK_27000KHZ << MIPI_FREF_D_IND));
> +	/* post divider */
> +	ret |= anx7625_write_and(ctx, ctx->i2c.rx_p1_client,
> +				 MIPI_DIGITAL_PLL_8, 0x0f);
> +	ret |= anx7625_write_or(ctx, ctx->i2c.rx_p1_client, MIPI_DIGITAL_PLL_8,
> +				post_divider << 4);
> +
> +	/* add patch for MIS2-125 (5pcs ANX7625 fail ATE MBIST test) */
> +	ret |= anx7625_write_and(ctx, ctx->i2c.rx_p1_client, MIPI_DIGITAL_PLL_7,
> +				 ~MIPI_PLL_VCO_TUNE_REG_VAL);
> +
> +	/* reset ODFC PLL */
> +	ret |= anx7625_write_and(ctx, ctx->i2c.rx_p1_client, MIPI_DIGITAL_PLL_7,
> +				 ~MIPI_PLL_RESET_N);
> +	ret |= anx7625_write_or(ctx, ctx->i2c.rx_p1_client, MIPI_DIGITAL_PLL_7,
> +				MIPI_PLL_RESET_N);
> +
> +	if (ret < 0)
> +		DRM_ERROR("IO error.\n");
> +
> +	return ret;
> +}
> +
> +static int anx7625_dsi_video_timing_config(struct anx7625_data *ctx)
> +{
> +	struct device *dev = &ctx->client->dev;
> +	unsigned long m, n;
> +	u16 htotal;
> +	int ret;
> +	u8 post_divider = 0;
> +
> +	ret = anx7625_calculate_m_n(ctx->dt.pixelclock.min * 1000,
> +				    &m, &n, &post_divider);
> +
> +	if (ret != 0) {
> +		DRM_ERROR("cannot get property m n value.\n");
> +		return -EINVAL;
> +	}

	if (ret)
		return ret;

> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "compute M(%lu), N(%lu), divider(%d).\n",
> +			     m, n, post_divider);
> +
> +	/* configure pixel clock */
> +	ret = anx7625_reg_write(ctx, ctx->i2c.rx_p0_client, PIXEL_CLOCK_L,
> +				(ctx->dt.pixelclock.min / 1000) & 0xFF);
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p0_client, PIXEL_CLOCK_H,
> +				 (ctx->dt.pixelclock.min / 1000) >> 8);
> +	/* lane count */
> +	ret |= anx7625_write_and(ctx, ctx->i2c.rx_p1_client,
> +			MIPI_LANE_CTRL_0, 0xfc);
> +	if (ctx->pdata.dsi_lanes)
> +		ret |= anx7625_write_or(ctx, ctx->i2c.rx_p1_client,
> +					MIPI_LANE_CTRL_0,
> +					(ctx->pdata.dsi_lanes - 1));
> +	else
> +		ret |= anx7625_write_or(ctx, ctx->i2c.rx_p1_client,
> +					MIPI_LANE_CTRL_0, 3);
> +
> +	/* Htotal */
> +	htotal = ctx->dt.hactive.min + ctx->dt.hfront_porch.min +
> +		ctx->dt.hback_porch.min + ctx->dt.hsync_len.min;
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p2_client,
> +			HORIZONTAL_TOTAL_PIXELS_L, htotal & 0xFF);
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p2_client,
> +			HORIZONTAL_TOTAL_PIXELS_H, htotal >> 8);
> +	/* Hactive */
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p2_client,
> +			HORIZONTAL_ACTIVE_PIXELS_L, ctx->dt.hactive.min & 0xFF);
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p2_client,
> +			HORIZONTAL_ACTIVE_PIXELS_H, ctx->dt.hactive.min >> 8);
> +	/* HFP */
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p2_client,
> +			HORIZONTAL_FRONT_PORCH_L, ctx->dt.hfront_porch.min);
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p2_client,
> +			HORIZONTAL_FRONT_PORCH_H,
> +			ctx->dt.hfront_porch.min >> 8);
> +	/* HWS */
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p2_client,
> +			HORIZONTAL_SYNC_WIDTH_L, ctx->dt.hsync_len.min);
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p2_client,
> +			HORIZONTAL_SYNC_WIDTH_H, ctx->dt.hsync_len.min >> 8);
> +	/* HBP */
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p2_client,
> +			HORIZONTAL_BACK_PORCH_L, ctx->dt.hback_porch.min);
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p2_client,
> +			HORIZONTAL_BACK_PORCH_H, ctx->dt.hback_porch.min >> 8);
> +	/* Vactive */
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p2_client, ACTIVE_LINES_L,
> +			ctx->dt.vactive.min);
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p2_client, ACTIVE_LINES_H,
> +			ctx->dt.vactive.min >> 8);
> +	/* VFP */
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p2_client,
> +			VERTICAL_FRONT_PORCH, ctx->dt.vfront_porch.min);
> +	/* VWS */
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p2_client,
> +			VERTICAL_SYNC_WIDTH, ctx->dt.vsync_len.min);
> +	/* VBP */
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p2_client,
> +			VERTICAL_BACK_PORCH, ctx->dt.vback_porch.min);
> +	/* M value */
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p1_client,
> +			MIPI_PLL_M_NUM_23_16, (m >> 16) & 0xff);
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p1_client,
> +			MIPI_PLL_M_NUM_15_8, (m >> 8) & 0xff);
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p1_client,
> +			MIPI_PLL_M_NUM_7_0, (m & 0xff));
> +	/* N value */
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p1_client,
> +			MIPI_PLL_N_NUM_23_16, (n >> 16) & 0xff);
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p1_client,
> +			MIPI_PLL_N_NUM_15_8, (n >> 8) & 0xff);
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p1_client, MIPI_PLL_N_NUM_7_0,
> +			(n & 0xff));
> +	/* diff */
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p1_client,
> +			MIPI_DIGITAL_ADJ_1, 0x37);
> +
> +	ret |= anx7625_odfc_config(ctx, post_divider - 1);
> +
> +	if (ret < 0)
> +		DRM_ERROR("mipi dsi setup IO error.\n");
> +
> +	return ret;
> +}
> +
> +static int anx7625_swap_dsi_lane3(struct anx7625_data *ctx)
> +{
> +	int val;
> +
> +	/* swap MIPI-DSI data lane 3 P and N */
> +	val = anx7625_reg_read(ctx, ctx->i2c.rx_p1_client, MIPI_SWAP);
> +	if (val < 0) {
> +		DRM_ERROR("IO error : access MIPI_SWAP.\n");
> +		return -EIO;
> +	}
> +
> +	val |= (1 << MIPI_SWAP_CH3);
> +	return anx7625_reg_write(ctx, ctx->i2c.rx_p1_client, MIPI_SWAP, val);
> +}
> +
> +static int anx7625_api_dsi_config(struct anx7625_data *ctx)
> +
> +{
> +	int val, ret;
> +
> +	/* swap MIPI-DSI data lane 3 P and N */
> +	ret = anx7625_swap_dsi_lane3(ctx);
> +	if (ret < 0) {
> +		DRM_ERROR("IO error : swap dsi lane 3 failed.\n");
> +		return ret;
> +	}
> +
> +	/* DSI clock settings */
> +	val = (0 << MIPI_HS_PWD_CLK)		|
> +		(0 << MIPI_HS_RT_CLK)		|
> +		(0 << MIPI_PD_CLK)		|
> +		(1 << MIPI_CLK_RT_MANUAL_PD_EN)	|
> +		(1 << MIPI_CLK_HS_MANUAL_PD_EN)	|
> +		(0 << MIPI_CLK_DET_DET_BYPASS)	|
> +		(0 << MIPI_CLK_MISS_CTRL)	|
> +		(0 << MIPI_PD_LPTX_CH_MANUAL_PD_EN);
> +	ret = anx7625_reg_write(ctx, ctx->i2c.rx_p1_client,
> +				MIPI_PHY_CONTROL_3, val);
> +
> +	/*
> +	 * Decreased HS prepare timing delay from 160ns to 80ns work with
> +	 *     a) Dragon board 810 series (Qualcomm AP)
> +	 *     b) Moving Pixel DSI source (PG3A pattern generator +
> +	 *	P332 D-PHY Probe) default D-PHY timing
> +	 *	5ns/step
> +	 */
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p1_client,
> +				 MIPI_TIME_HS_PRPR, 0x10);
> +
> +	/* enable DSI mode*/
> +	ret |= anx7625_write_or(ctx, ctx->i2c.rx_p1_client, MIPI_DIGITAL_PLL_18,
> +				SELECT_DSI << MIPI_DPI_SELECT);
> +
> +	ret |= anx7625_dsi_video_timing_config(ctx);
> +	if (ret < 0) {
> +		DRM_ERROR("dsi video timing config failed\n");
> +		return ret;
> +	}
> +
> +	/* toggle m, n ready */
> +	ret = anx7625_write_and(ctx, ctx->i2c.rx_p1_client, MIPI_DIGITAL_PLL_6,
> +				~(MIPI_M_NUM_READY | MIPI_N_NUM_READY));
> +	usleep_range(1000, 1100);
> +	ret |= anx7625_write_or(ctx, ctx->i2c.rx_p1_client, MIPI_DIGITAL_PLL_6,
> +				MIPI_M_NUM_READY | MIPI_N_NUM_READY);
> +
> +	/* configure integer stable register */
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p1_client,
> +				 MIPI_VIDEO_STABLE_CNT, 0x02);
> +	/* power on MIPI RX */
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p1_client,
> +				 MIPI_LANE_CTRL_10, 0x00);
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p1_client,
> +				 MIPI_LANE_CTRL_10, 0x80);
> +
> +	if (ret < 0)
> +		DRM_ERROR("IO error : mipi dsi enable init failed.\n");
> +
> +	return ret;
> +}
> +
> +static int anx7625_dsi_config(struct anx7625_data *ctx)
> +{
> +	struct device *dev = &ctx->client->dev;
> +	int ret;
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "config dsi.\n");
> +
> +	/* DSC disable */
> +	ret = anx7625_write_and(ctx, ctx->i2c.rx_p0_client,
> +				R_DSC_CTRL_0, ~DSC_EN);
> +
> +	ret |= anx7625_api_dsi_config(ctx);
> +
> +	if (ret < 0) {
> +		DRM_ERROR("IO error : api dsi config error.\n");
> +	} else {
> +		/* set MIPI RX EN */
> +		ret = anx7625_write_or(ctx, ctx->i2c.rx_p0_client,
> +				       AP_AV_STATUS, AP_MIPI_RX_EN);
> +		/* clear mute flag */
> +		ret |= anx7625_write_and(ctx, ctx->i2c.rx_p0_client,
> +					 AP_AV_STATUS, (u8)~AP_MIPI_MUTE);
> +		if (ret < 0)
> +			DRM_ERROR("IO error : enable mipi rx failed.\n");
> +		else
> +			DRM_DEV_DEBUG_DRIVER(dev, "success to config DSI\n");
> +	}
> +
> +	return ret;
> +}
> +
> +static int anx7625_api_dpi_config(struct anx7625_data *ctx)
> +{
> +	u16 freq = ctx->dt.pixelclock.min / 1000;
> +	int ret;
> +
> +	/* configure pixel clock */
> +	ret = anx7625_reg_write(ctx, ctx->i2c.rx_p0_client,
> +				PIXEL_CLOCK_L, freq & 0xFF);
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p0_client,
> +				 PIXEL_CLOCK_H, (freq >> 8));
> +
> +	/* set DPI mode */
> +	/* set to DPI PLL module sel */
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p1_client,
> +				 MIPI_DIGITAL_PLL_9, 0x20);
> +	/* power down MIPI */
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p1_client,
> +				 MIPI_LANE_CTRL_10, 0x08);
> +	/* enable DPI mode */
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p1_client,
> +				 MIPI_DIGITAL_PLL_18, 0x1C);
> +	/* set first edge */
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.tx_p2_client,
> +				 VIDEO_CONTROL_0, 0x05);
> +	if (ret < 0)
> +		DRM_ERROR("IO error : dpi phy set failed.\n");
> +
> +	return ret;
> +}
> +
> +static int anx7625_dpi_config(struct anx7625_data *ctx)
> +{
> +	struct device *dev = &ctx->client->dev;
> +	int ret;
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "config dpi\n");
> +
> +	/* DSC disable */
> +	ret = anx7625_write_and(ctx, ctx->i2c.rx_p0_client,
> +				R_DSC_CTRL_0, ~DSC_EN);
> +	if (ret < 0) {
> +		DRM_ERROR("IO error : disable dsc failed.\n");
> +		return ret;
> +	}
> +
> +	ret = anx7625_config_bit_matrix(ctx);
> +	if (ret < 0) {
> +		DRM_ERROR("config bit matrix failed.\n");
> +		return ret;
> +	}
> +
> +	ret = anx7625_api_dpi_config(ctx);
> +	if (ret < 0) {
> +		DRM_ERROR("mipi phy(dpi) setup failed.\n");
> +		return ret;
> +	}
> +
> +	/* set MIPI RX EN */
> +	ret = anx7625_write_or(ctx, ctx->i2c.rx_p0_client,
> +			       AP_AV_STATUS, AP_MIPI_RX_EN);
> +	/* clear mute flag */
> +	ret |= anx7625_write_and(ctx, ctx->i2c.rx_p0_client,
> +				 AP_AV_STATUS, (u8)~AP_MIPI_MUTE);
> +	if (ret < 0)
> +		DRM_ERROR("IO error : enable mipi rx failed.\n");
> +
> +	return ret;
> +}
> +
> +const u8 ANX_OUI[3] = { 0x00, 0x22, 0xB9 };
> +static int is_anx_dongle(struct anx7625_data *ctx)
> +{
> +	u8 buf[3];
> +
> +	/* 0x0500~0x0502: BRANCH_IEEE_OUI */
> +	sp_tx_aux_dpcdread_bytes(ctx, 0x00, 0x05, 0x00, sizeof(buf), buf);
> +	if (memcmp(buf, ANX_OUI, sizeof(buf)) == 0)
> +		return 1;
> +
> +	return 0;
> +}
> +
> +static void sp_tx_get_rx_bw(struct anx7625_data *ctx, u8 *bw)
> +{
> +	u8 data_buf[4];
> +	/*
> +	 * When ANX dongle connected, if CHIP_ID = 0x7750, bandwidth is 6.75G,
> +	 * because ANX7750 DPCD 0x052x was not available.
> +	 */
> +	if (is_anx_dongle(ctx)) {
> +		sp_tx_aux_dpcdread_bytes(ctx, 0x00, 0x05, 0x03, 0x04, data_buf);
> +		if (data_buf[0] == 0x37 && data_buf[1] == 0x37 &&
> +		    data_buf[2] == 0x35 && data_buf[3] == 0x30) {
> +			/* 0x19 : 6.75G */
> +			*bw = 0x19;
> +		} else {
> +			sp_tx_aux_dpcdread_bytes(ctx, 0x00, 0x05, 0x21, 1, bw);
> +			/*
> +			 * some ANX dongle read out value 0,
> +			 * retry standard register.
> +			 */
> +			if (((*bw) == 0) || ((*bw) == 0xff))
> +				sp_tx_aux_dpcdread_bytes(ctx, 0x00, 0x00,
> +							 DPCD_MAX_LINK_RATE,
> +							 1, bw);
> +		}
> +	} else {
> +		sp_tx_aux_dpcdread_bytes(ctx, 0x00, 0x00,
> +					 DPCD_MAX_LINK_RATE, 1, bw);
> +	}
> +}
> +
> +static void anx7625_dp_start(struct anx7625_data *ctx)
> +{
> +	int ret;
> +
> +	if (!ctx->display_timing_valid) {
> +		DRM_ERROR("mipi drm haven't set display timing yet.\n");
> +		return;
> +	}
> +
> +	ret = anx7625_config_audio_input(ctx);
> +	if (ret < 0)
> +		DRM_ERROR("config audio input failed.\n");

return after error?

> +
> +	if (ctx->pdata.dsi_supported)
> +		ret = anx7625_dsi_config(ctx);
> +	else
> +		ret = anx7625_dpi_config(ctx);
> +
> +	if (ret < 0)
> +		DRM_ERROR("MIPI phy setup error.\n");
> +}
> +
> +static void anx7625_dp_stop(struct anx7625_data *ctx)
> +{
> +	struct device *dev = &ctx->client->dev;
> +	int ret;
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "stop dp output\n");
> +
> +	/*
> +	 * video disable: 0x72:08 bit 7 = 0;
> +	 * audio disable: 0x70:87 bit 0 = 0;
> +	 */
> +	ret = anx7625_write_and(ctx, ctx->i2c.tx_p0_client, 0x87, 0xfe);
> +	ret |= anx7625_write_and(ctx, ctx->i2c.tx_p2_client, 0x08, 0x7f);
> +
> +	ret |= anx7625_video_mute_control(ctx, 1);
> +	if (ret < 0)
> +		DRM_ERROR("IO error : mute video failed\n");
> +}
> +
> +static int sp_tx_rst_aux(struct anx7625_data *ctx)
> +{
> +	int ret;
> +
> +	ret = anx7625_write_or(ctx, ctx->i2c.tx_p2_client, RST_CTRL2,
> +			       AUX_RST);
> +	ret |= anx7625_write_and(ctx, ctx->i2c.tx_p2_client, RST_CTRL2,
> +				 ~AUX_RST);
> +	return ret;
> +}
> +
> +static int sp_tx_aux_wr(struct anx7625_data *ctx, u8 offset)
> +{
> +	int ret;
> +
> +	ret = anx7625_reg_write(ctx, ctx->i2c.rx_p0_client,
> +				AP_AUX_BUFF_START, offset);
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p0_client,
> +				 AP_AUX_COMMAND, 0x04);
> +	ret |= anx7625_write_or(ctx, ctx->i2c.rx_p0_client,
> +				AP_AUX_CTRL_STATUS, AP_AUX_CTRL_OP_EN);
> +	return (ret | wait_aux_op_finish(ctx));
> +}
> +
> +static int sp_tx_aux_rd(struct anx7625_data *ctx, u8 len_cmd)
> +{
> +	int ret;
> +
> +	ret = anx7625_reg_write(ctx, ctx->i2c.rx_p0_client,
> +				AP_AUX_COMMAND, len_cmd);
> +	ret |= anx7625_write_or(ctx, ctx->i2c.rx_p0_client,
> +				AP_AUX_CTRL_STATUS, AP_AUX_CTRL_OP_EN);
> +	return (ret | wait_aux_op_finish(ctx));
> +}
> +
> +static int sp_tx_get_edid_block(struct anx7625_data *ctx)
> +{
> +	int c = 0;
> +	struct device *dev = &ctx->client->dev;
> +
> +	sp_tx_aux_wr(ctx, 0x7e);
> +	sp_tx_aux_rd(ctx, 0x01);
> +	c = anx7625_reg_read(ctx, ctx->i2c.rx_p0_client, AP_AUX_BUFF_START);
> +	if (c < 0) {
> +		DRM_ERROR("IO error : access AUX BUFF.\n");
> +		return -EIO;
> +	}
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, " EDID Block = %d\n", c + 1);
> +
> +	if (c > 3)
> +		c = 1;
> +
> +	return c;
> +}
> +
> +static int edid_read(struct anx7625_data *ctx,
> +		     u8 offset, u8 *pblock_buf)
> +{
> +	u8 c, cnt = 0;
                  ^^^

"c" needs to be an integer.  "cnt" should be an int too, but it doesn't
cause a bug either way.  Delete the bogus "cnt" initialization.

> +	struct device *dev = &ctx->client->dev;
> +
> +	c = 0;
        ^^^^^
Delete.

> +	for (cnt = 0; cnt < 3; cnt++) {
> +		sp_tx_aux_wr(ctx, offset);
> +		/* set I2C read com 0x01 mot = 0 and read 16 bytes */
> +		c = sp_tx_aux_rd(ctx, 0xf1);
> +
> +		if (c == 1) {

1 is a magic number here.  We need to check for negative returns as
well.


> +			sp_tx_rst_aux(ctx);
> +			DRM_DEV_DEBUG_DRIVER(dev, "edid read failed, reset!\n");
> +			cnt++;
> +		} else {
> +			anx7625_reg_block_read(ctx, ctx->i2c.rx_p0_client,
> +					       AP_AUX_BUFF_START,
> +					       MAX_DPCD_BUFFER_SIZE,
> +					       pblock_buf);
> +			return 0;
> +		}
> +	}
> +
> +	return 1;
> +}
> +
> +static int segments_edid_read(struct anx7625_data *ctx,
> +			      u8 segment, u8 *buf, u8 offset)
> +{
> +	u8 c, cnt = 0;

c needs to be an int.

> +	int ret;
> +	struct device *dev = &ctx->client->dev;
> +
> +	/* write address only */
> +	ret = anx7625_reg_write(ctx, ctx->i2c.rx_p0_client,
> +				AP_AUX_ADDR_7_0, 0x30);
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p0_client,
> +				 AP_AUX_COMMAND, 0x04);
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p0_client,
> +				 AP_AUX_CTRL_STATUS,
> +				 AP_AUX_CTRL_ADDRONLY | AP_AUX_CTRL_OP_EN);
> +
> +	ret |= wait_aux_op_finish(ctx);
> +	/* write segment address */
> +	ret |= sp_tx_aux_wr(ctx, segment);
> +	/* data read */
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p0_client,
> +				 AP_AUX_ADDR_7_0, 0x50);
> +	if (ret < 0) {
> +		DRM_ERROR("IO error : aux initial failed.\n");
> +		return ret;
> +	}
> +
> +	for (cnt = 0; cnt < 3; cnt++) {
> +		sp_tx_aux_wr(ctx, offset);
> +		/* set I2C read com 0x01 mot = 0 and read 16 bytes */
> +		c = sp_tx_aux_rd(ctx, 0xf1);
> +
> +		if (c == 1) {


Where does 1 come from?  We need to check for negative returns.

> +			ret = sp_tx_rst_aux(ctx);
> +			DRM_DEV_ERROR(dev, "segment read failed, reset!\n");
> +			cnt++;
> +		} else {
> +			ret = anx7625_reg_block_read(ctx, ctx->i2c.rx_p0_client,
> +						     AP_AUX_BUFF_START,
> +						     MAX_DPCD_BUFFER_SIZE, buf);
> +			return ret;
> +		}
> +	}
> +
> +	return ret;
> +}
> +
> +static int sp_tx_edid_read(struct anx7625_data *ctx,
> +			   u8 *pedid_blocks_buf)
> +{
> +	u8 offset, edid_pos;
> +	int count, blocks_num;
> +	u8 pblock_buf[MAX_DPCD_BUFFER_SIZE];
> +	u8 i, j;
> +	u8 g_edid_break = 0;
> +	int ret;
> +	struct device *dev = &ctx->client->dev;
> +
> +	/* address initial */
> +	ret = anx7625_reg_write(ctx, ctx->i2c.rx_p0_client,
> +				AP_AUX_ADDR_7_0, 0x50);
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p0_client,
> +				 AP_AUX_ADDR_15_8, 0);
> +	ret |= anx7625_write_and(ctx, ctx->i2c.rx_p0_client,
> +				 AP_AUX_ADDR_19_16, 0xf0);
> +	if (ret < 0) {
> +		DRM_ERROR("access aux channel IO error.\n");
> +		return -EIO;
> +	}
> +
> +	blocks_num = sp_tx_get_edid_block(ctx);
> +	if (blocks_num < 0)
> +		return blocks_num;
> +
> +	count = 0;
> +
> +	do {
> +		switch (count) {
> +		case 0:
> +		case 1:
> +			for (i = 0; i < 8; i++) {
> +				offset = (i + count * 8) * MAX_DPCD_BUFFER_SIZE;
> +				g_edid_break = edid_read(ctx, offset,
> +							 pblock_buf);
> +
> +				if (g_edid_break == 1)
> +					break;
> +
> +				memcpy(&pedid_blocks_buf[offset],
> +				       pblock_buf,
> +				       MAX_DPCD_BUFFER_SIZE);
> +			}
> +
> +			break;
> +		case 2:
> +			offset = 0x00;
> +
> +			for (j = 0; j < 8; j++) {
> +				edid_pos = (j + count * 8) *
> +					MAX_DPCD_BUFFER_SIZE;
> +
> +				if (g_edid_break == 1)
> +					break;
> +
> +				segments_edid_read(ctx, count / 2,
> +						   pblock_buf, offset);
> +				memcpy(&pedid_blocks_buf[edid_pos],
> +				       pblock_buf,
> +				       MAX_DPCD_BUFFER_SIZE);
> +				offset = offset + 0x10;
> +			}
> +
> +			break;
> +		case 3:
> +			offset = 0x80;
> +
> +			for (j = 0; j < 8; j++) {
> +				edid_pos = (j + count * 8) *
> +					MAX_DPCD_BUFFER_SIZE;
> +				if (g_edid_break == 1)
> +					break;
> +
> +				segments_edid_read(ctx, count / 2,
> +						   pblock_buf, offset);
> +				memcpy(&pedid_blocks_buf[edid_pos],
> +				       pblock_buf,
> +				       MAX_DPCD_BUFFER_SIZE);
> +				offset = offset + 0x10;
> +			}
> +
> +			break;
> +		default:
> +			break;
> +		}
> +
> +		count++;
> +
> +	} while (blocks_num >= count);
> +
> +	/* check edid data */
> +	if (drm_edid_is_valid((struct edid *)pedid_blocks_buf) == false)
> +		DRM_DEV_ERROR(dev, "WARNING! edid check failed!\n");
> +
> +	/* reset aux channel */
> +	sp_tx_rst_aux(ctx);
> +
> +	return blocks_num;
> +}
> +
> +static void anx7625_power_on(struct anx7625_data *ctx)
> +{
> +	struct device *dev = &ctx->client->dev;
> +
> +	if (ctx->pdata.low_power_mode) {

Flip this around.

	if (!ctx->pdata.low_power_mode) {
		DRM_DEV_DEBUG_DRIVER(dev, "Anx7625 not low power mode!\n");
		return;
	}

> +		/* power on pin enable */
> +		gpio_set_value(ctx->pdata.gpio_p_on, 1);
> +		usleep_range(10000, 11000);
> +		/* power reset pin enable */
> +		gpio_set_value(ctx->pdata.gpio_reset, 1);
> +		usleep_range(10000, 11000);
> +
> +		DRM_DEV_DEBUG_DRIVER(dev, "Anx7625 power on !\n");
> +	} else {
> +		DRM_DEV_DEBUG_DRIVER(dev, "Anx7625 not low power mode!\n");
> +	}
> +}
> +
> +static void anx7625_power_standby(struct anx7625_data *ctx)
> +{
> +	struct device *dev = &ctx->client->dev;
> +
> +	if (ctx->pdata.low_power_mode) {

Flip.

> +		gpio_set_value(ctx->pdata.gpio_reset, 0);
> +		usleep_range(1000, 1100);
> +		gpio_set_value(ctx->pdata.gpio_p_on, 0);
> +		usleep_range(1000, 1100);
> +		DRM_DEV_DEBUG_DRIVER(dev, "anx7625 power down\n");
> +	} else {
> +		DRM_DEV_DEBUG_DRIVER(dev, "anx7625 not low power mode!\n");
> +	}
> +}
> +
> +/* basic configurations of ANX7625 */
> +static void anx7625_config(struct anx7625_data *ctx)
> +{
> +	anx7625_reg_write(ctx, ctx->i2c.rx_p0_client,
> +			  XTAL_FRQ_SEL, XTAL_FRQ_27M);
> +}
> +
> +static void anx7625_disable_pd_protocol(struct anx7625_data *ctx)
> +{
> +	struct device *dev = &ctx->client->dev;
> +	int ret;
> +
> +	/* reset main ocm */
> +	ret = anx7625_reg_write(ctx, ctx->i2c.rx_p0_client, 0x88, 0x40);
> +	/* Disable PD */
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p0_client,
> +				 AP_AV_STATUS, AP_DISABLE_PD);
> +	/* release main ocm */
> +	ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p0_client, 0x88, 0x00);
> +
> +	if (ret < 0)
> +		DRM_DEV_DEBUG_DRIVER(dev, "disable PD feature failed.\n");
> +	else
> +		DRM_DEV_DEBUG_DRIVER(dev, "disable PD feature succeeded.\n");
> +}
> +
> +static void anx7625_power_on_init(struct anx7625_data *ctx)
> +{
> +	int retry_count, i;
> +	int ret = 0;
               ^^^^
Delete initialization.

> +	struct device *dev = &ctx->client->dev;
> +
> +	for (retry_count = 0; retry_count < 3; retry_count++) {
> +		anx7625_power_on(ctx);
> +		anx7625_config(ctx);
> +
> +		for (i = 0; i < OCM_LOADING_TIME; i++) {
> +			/* check interface workable */
> +			ret = anx7625_reg_read(ctx, ctx->i2c.rx_p0_client,
> +					       FLASH_LOAD_STA);
> +			if (ret < 0) {
> +				DRM_ERROR("IO error : access flash load.\n");
> +				return;
> +			}
> +			if ((ret & FLASH_LOAD_STA_CHK) == FLASH_LOAD_STA_CHK) {
> +				anx7625_disable_pd_protocol(ctx);
> +				DRM_DEV_DEBUG_DRIVER(dev,
> +						     "Firmware ver %02x%02x,",
> +					anx7625_reg_read(ctx,
> +							 ctx->i2c.rx_p0_client,
> +							 OCM_FW_VERSION),
> +					anx7625_reg_read(ctx,
> +							 ctx->i2c.rx_p0_client,
> +							 OCM_FW_REVERSION));
> +				DRM_DEV_DEBUG_DRIVER(dev, "Driver version %s\n",
> +						     ANX7625_DRV_VERSION);
> +
> +				return;
> +			}
> +			usleep_range(1000, 1100);
> +		}
> +		anx7625_power_standby(ctx);
> +	}
> +}
> +
> +static int anx7625_extcon_notifier(struct notifier_block *nb,
> +				   unsigned long event, void *ptr)
> +{
> +	struct anx7625_data *ctx =
> +		container_of(nb, struct anx7625_data, event_nb);
> +
> +	schedule_work(&ctx->extcon_wq);
> +	return NOTIFY_DONE;
> +}
> +
> +static void anx7625_chip_control(struct anx7625_data *ctx)
> +{
> +	int state = extcon_get_state(ctx->extcon, EXTCON_DISP_DP);
> +
> +	if (ctx->pdata.low_power_mode) {
> +		if (state > 0) {
> +			if (atomic_read(&ctx->power_status) == 0) {
> +				anx7625_power_on_init(ctx);
> +				atomic_set(&ctx->power_status, 1);
> +			}
> +		} else {
> +			if (atomic_read(&ctx->power_status) == 1) {
> +				anx7625_power_standby(ctx);
> +				atomic_set(&ctx->power_status, 0);
> +			}
> +		}
> +	}
> +}
> +
> +static void anx7625_extcon_work(struct work_struct *work)
> +{
> +	struct anx7625_data *ctx =
> +		container_of(work, struct anx7625_data, extcon_wq);
> +
> +	mutex_lock(&ctx->lock);
> +	anx7625_chip_control(ctx);
> +	mutex_unlock(&ctx->lock);
> +}
> +
> +static int anx7625_extcon_notifier_init(struct anx7625_data *ctx)
> +{
> +	int ret;
> +	struct device *dev = &ctx->client->dev;
> +
> +	ctx->event_nb.notifier_call = anx7625_extcon_notifier;
> +	INIT_WORK(&ctx->extcon_wq, anx7625_extcon_work);
> +	ret = devm_extcon_register_notifier(&ctx->client->dev, ctx->extcon,
> +					    EXTCON_DISP_DP, &ctx->event_nb);
> +	if (ret) {
> +		DRM_DEV_ERROR(dev, "failed to register notifier for DP");
> +		return ret;
> +	}
> +	return 0;
> +}
> +
> +static void anx7625_free_gpio(struct anx7625_data *platform)
> +{
> +	if (platform->pdata.gpio_intr_hpd)
> +		gpio_free(platform->pdata.gpio_intr_hpd);
> +
> +	if (platform->pdata.low_power_mode) {
> +		gpio_free(platform->pdata.gpio_reset);
> +		gpio_free(platform->pdata.gpio_p_on);
> +	}
> +}
> +
> +static int anx7625_init_gpio(struct anx7625_data *platform)
> +{
> +	int ret = 0;
> +	struct device *dev = &platform->client->dev;
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "anx7625 init gpio\n");
> +
> +	if (platform->pdata.low_power_mode) {
> +		/* gpio for chip power down */
> +		ret = gpio_request(platform->pdata.gpio_p_on,
> +				   "anx7625_p_on_ctl");
> +		if (ret) {
> +			DRM_DEV_ERROR(dev, "failed to request gpio %d\n",
> +				      platform->pdata.gpio_p_on);
> +			goto err0;

Choose error labels that say what the error handling does.  Imagine if
we didn't have names, we just and "int var1, var2, var3;  func1(var2);".
It's the same thing for error labels, the name should be useful.

In this case the error handling is wrong because the gpio_request()
failed so there is no cleanup required.  We should always just clean
up the most recent allocation.  In this case since we haven't allocated
anything we can just return;

		if (ret) {
			DRM_DEV_ERROR(dev, "failed to request gpio %d\n",
				      platform->pdata.gpio_p_on);
			return ret;
		}


> +		}
> +		/* gpio for chip reset */
> +		ret = gpio_request(platform->pdata.gpio_reset,
> +				   "anx7625_reset_n");
> +		if (ret) {
> +			DRM_DEV_ERROR(dev, "failed to request gpio %d\n",
> +				      platform->pdata.gpio_reset);
> +			goto err1;

The most recent allocation is so gpio_p_on "goto free_gpio_p_on;".

> +		}
> +	}
> +
> +	if (platform->pdata.gpio_intr_hpd) {
> +		/* gpio for chip interface communaction */
> +		ret = gpio_request(platform->pdata.gpio_intr_hpd,
> +				   "anx7625_hpd");
> +		if (ret) {
> +			DRM_DEV_ERROR(dev, "failed to request gpio %d\n",
> +				      platform->pdata.gpio_intr_hpd);
> +			goto err2;

goto free_gpio_reset;

> +		}
> +	}
> +
> +	goto out;

Just "return 0;"  "return 0;" is immediately readable.  The little goto
hops around are like chasing a rabbit.  Fun for a little while but
tiring in the end.

free_gpio_reset:
	if (platform->pdata.low_power_mode)
		gpio_free(platform->pdata.gpio_reset);
free_gpio_p_on:
	if (platform->pdata.low_power_mode)
		gpio_free(platform->pdata.gpio_p_on);

	return ret;


> +
> +err2:
> +	if (platform->pdata.gpio_intr_hpd)
> +		gpio_free(platform->pdata.gpio_intr_hpd);
> +err1:
> +	if (platform->pdata.low_power_mode)
> +		gpio_free(platform->pdata.gpio_reset);
> +err0:
> +	if (platform->pdata.low_power_mode)
> +		gpio_free(platform->pdata.gpio_p_on);
> +
> +	return 1;

returning 1 here is a bug because it get propogated outside the driver.

> +out:
> +
> +	return 0;
> +}
> +
> +static void anx7625_stop_dp_work(struct anx7625_data *ctx)
> +{
> +	ctx->hpd_status = 0;
> +	ctx->hpd_high_cnt = 0;
> +	ctx->display_timing_valid = 0;
> +
> +	kfree(ctx->slimport_edid_p);
> +	ctx->slimport_edid_p = NULL;
> +
> +	if (ctx->pdata.low_power_mode == 0)
> +		anx7625_disable_pd_protocol(ctx);
> +}
> +
> +static void anx7625_start_dp_work(struct anx7625_data *ctx)
> +{
> +	int ret;
> +	u8 buf[MAX_DPCD_BUFFER_SIZE];
> +	u8 hdcp_cap;
> +	struct device *dev = &ctx->client->dev;
> +
> +	u8 sp_tx_bw; /* linktraining banwidth */
> +	u8 sp_tx_lane_count; /* link training lane count */
> +
> +	if (ctx->hpd_high_cnt >= 2) {
> +		DRM_DEV_DEBUG_DRIVER(dev, "anx7625 filter useless HPD\n");
> +		return;
> +	}
> +
> +	ctx->hpd_high_cnt++;
> +
> +	sp_tx_get_rx_bw(ctx, &sp_tx_bw);
> +
> +	sp_tx_aux_dpcdread_bytes(ctx, 0x00, 0x00, DPCD_MAX_LANE_COUNT,
> +				 1, &sp_tx_lane_count);
> +
> +	sp_tx_lane_count = sp_tx_lane_count & 0x1f;
> +	sp_tx_aux_dpcdread_bytes(ctx, 0x06, 0x80, 0x28, 1, buf);/* read Bcap */
> +
> +	hdcp_cap = buf[0] & 0x01;
> +
> +	/* not support HDCP */
> +	ret = anx7625_write_and(ctx, ctx->i2c.rx_p1_client, 0xee, 0x9f);
> +
> +	if (hdcp_cap == 0x01)
> +		DRM_DEV_DEBUG_DRIVER(dev, "HDCP1.4\n");
> +
> +	/* try auth flag */
> +	ret |= anx7625_write_or(ctx, ctx->i2c.rx_p1_client, 0xec, 0x10);
> +	/* interrupt for DRM */
> +	ret |= anx7625_write_or(ctx, ctx->i2c.rx_p1_client, 0xff, 0x01);
> +	if (ret < 0)
> +		return;
> +	DRM_DEV_DEBUG_DRIVER(dev, "MAX BW=%02x, MAX Lane cnt=%02x, HDCP=%02x\n",
> +			     (u32)sp_tx_bw,
> +			     (u32)sp_tx_lane_count,
> +			     (u32)hdcp_cap);
> +
> +	ret = anx7625_reg_read(ctx, ctx->i2c.rx_p1_client, 0x86);
> +	if (ret < 0)
> +		return;
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "Secure OCM version=%02x\n", ret);
> +}
> +
> +static void dp_hpd_change_handler(struct anx7625_data *ctx, bool on)
> +{
> +	struct device *dev = &ctx->client->dev;
> +
> +	/* hpd changed */
> +	DRM_DEV_DEBUG_DRIVER(dev, "dp_hpd_change_default_func: %d\n",
> +			     (u32)on);
> +
> +	if (on == 0) {
> +		DRM_DEV_DEBUG_DRIVER(dev, " HPD low\n");
> +		anx7625_stop_dp_work(ctx);
> +	} else {
> +		DRM_DEV_DEBUG_DRIVER(dev, " HPD high\n");
> +		anx7625_start_dp_work(ctx);
> +	}
> +
> +	ctx->hpd_status = on;
> +}
> +
> +static int anx7625_hpd_change_detect(struct anx7625_data *ctx)
> +{
> +	int intr_vector, status;
> +	struct device *dev = &ctx->client->dev;
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "power_status=%d\n",
> +			     (u32)atomic_read(&ctx->power_status));
> +
> +	status = anx7625_reg_write(ctx, ctx->i2c.tcpc_client,
> +				   INTR_ALERT_1, 0xFF);
> +	if (status < 0) {
> +		DRM_ERROR("IO error : clear alert register.\n");
> +		return status;
> +	}
> +
> +	intr_vector = anx7625_reg_read(ctx, ctx->i2c.rx_p0_client,
> +				       INTERFACE_CHANGE_INT);
> +	if (intr_vector < 0) {
> +		DRM_ERROR("IO error : access interrupt change register.\n");
> +		return intr_vector;
> +	}
> +	DRM_DEV_DEBUG_DRIVER(dev, "0x7e:0x44=%x\n", intr_vector);
> +	status = anx7625_reg_write(ctx, ctx->i2c.rx_p0_client,
> +				   INTERFACE_CHANGE_INT,
> +				   intr_vector & (~intr_vector));
> +	if (status < 0) {
> +		DRM_ERROR("IO error : clear interrupt change register.\n");
> +		return status;
> +	}
> +
> +	if (intr_vector & HPD_STATUS_CHANGE) {
> +		status = anx7625_reg_read(ctx, ctx->i2c.rx_p0_client,
> +					  SYSTEM_STSTUS);
> +		if (status < 0) {
> +			DRM_ERROR("IO error : clear interrupt status.\n");
> +			return status;
> +		}
> +
> +		DRM_DEV_DEBUG_DRIVER(dev, "0x7e:0x45=%x\n", status);
> +		dp_hpd_change_handler(ctx, status & HPD_STATUS);
> +		return 1;
> +	}
> +
> +	return 0;
> +}
> +
> +static void anx7625_work_func(struct work_struct *work)
> +{
> +	int event;
> +	struct anx7625_data *ctx = container_of(work,
> +						struct anx7625_data, work);
> +
> +	mutex_lock(&ctx->lock);
> +	event = anx7625_hpd_change_detect(ctx);
> +	mutex_unlock(&ctx->lock);
> +
> +	if (event < 0)
> +		return;
> +
> +	if (event && ctx->bridge_attached)
> +		drm_helper_hpd_irq_event(ctx->connector.dev);
> +}
> +
> +static irqreturn_t anx7625_intr_hpd_isr(int irq, void *data)
> +{
> +	struct anx7625_data *ctx = (struct anx7625_data *)data;
> +
> +	if (atomic_read(&ctx->power_status) != 1)
> +		return IRQ_NONE;
> +
> +	queue_work(ctx->workqueue, &ctx->work);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +#ifdef CONFIG_OF
> +static int anx7625_parse_dt(struct device *dev,
> +			    struct anx7625_platform_data *pdata)
> +{
> +	int ret;
> +	struct device_node *np = dev->of_node;
> +
> +	ret = of_property_read_u32(dev->of_node, "low-power-mode",
> +				   &pdata->low_power_mode);
> +	if (ret)
> +		pdata->low_power_mode = 1; /* default low power mode */
> +
> +	ret = of_property_read_u32(dev->of_node, "dsi-supported",
> +				   &pdata->dsi_supported);
> +	if (ret)
> +		pdata->dsi_supported = 1; /* default dsi mode */
> +
> +	ret = of_property_read_u32(dev->of_node, "extcon-supported",
> +				   &pdata->extcon_supported);
> +	if (ret)
> +		pdata->extcon_supported = 0;
> +
> +	ret = of_property_read_u32(dev->of_node, "internal-pannel-supported",
> +				   &pdata->internal_pannel);
> +	if (ret)
> +		pdata->internal_pannel = 0;
> +
> +	of_property_read_u32(dev->of_node, "dsi-channel-id",
> +			     &pdata->dsi_channel);
> +
> +	of_property_read_u32(dev->of_node, "dsi-lanes-num", &pdata->dsi_lanes);
> +
> +	pdata->host_node = of_graph_get_remote_node(np, 0, 0);
> +	if (pdata->host_node)
> +		of_node_put(pdata->host_node);
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "low_power_mode : %d, dsi_supported : %d\n",
> +			     pdata->low_power_mode, pdata->dsi_supported);
> +	DRM_DEV_DEBUG_DRIVER(dev, "dsi_channel : %d, dsi_lanes : %d, %s node\n",
> +			     pdata->dsi_channel, pdata->dsi_lanes,
> +			     (!pdata->host_node) ? "not" : "has");
> +
> +	if (pdata->low_power_mode) {
> +		pdata->gpio_p_on =
> +			of_get_named_gpio_flags(np, "pon-gpios",
> +						0, NULL);
> +
> +		pdata->gpio_reset =
> +			of_get_named_gpio_flags(np, "reset-gpios",
> +						0, NULL);
> +		DRM_DEV_DEBUG_DRIVER(dev, "gpio p_on : %d, reset : %d\n",
> +				     pdata->gpio_p_on, pdata->gpio_reset);
> +	}
> +
> +	pdata->gpio_intr_hpd =
> +		of_get_named_gpio_flags(np, "hpd-gpios", 0, NULL);
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "gpio hpd : %d\n", pdata->gpio_intr_hpd);
> +
> +	return 0;
> +}
> +#else
> +static int anx7625_parse_dt(struct device *dev,
> +			    struct anx7625_platform_data *pdata)
> +{
> +	return -ENODEV;
> +}
> +#endif
> +
> +static inline struct anx7625_data *connector_to_anx7625(struct drm_connector *c)
> +{
> +	return container_of(c, struct anx7625_data, connector);
> +}
> +
> +static inline struct anx7625_data *bridge_to_anx7625(struct drm_bridge *bridge)
> +{
> +	return container_of(bridge, struct anx7625_data, bridge);
> +}
> +
> +static int anx7625_read_hpd_status_p0(struct anx7625_data *ctx)
> +{
> +	return anx7625_reg_read(ctx, ctx->i2c.rx_p0_client, SYSTEM_STSTUS);
> +}
> +
> +static int anx7625_get_modes(struct drm_connector *connector)
> +{
> +	struct anx7625_data *ctx = connector_to_anx7625(connector);
> +	int err, num_modes = 0;
> +	int val, ret;
> +	struct s_edid_data *p_edid = (struct s_edid_data *)ctx->slimport_edid_p;
> +	struct device *dev = &ctx->client->dev;
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "drm get modes\n");
> +
> +	if (ctx->pdata.internal_pannel &&
> +	    ctx->pdata.low_power_mode &&
> +	    (!atomic_read(&ctx->power_status))) {
> +		anx7625_power_on_init(ctx);
> +		atomic_set(&ctx->power_status, 1);
> +
> +		ret = readx_poll_timeout(anx7625_read_hpd_status_p0,
> +					 ctx, val,
> +					 ((val & HPD_STATUS) || (val < 0)),
> +					 5000,
> +					 5000 * 100);
> +		if (ret) {
> +			DRM_DEV_ERROR(dev, "HPD status polling timeout!\n");
> +		} else {
> +			DRM_DEV_DEBUG_DRIVER(dev, "HPD raise up.\n");
> +			anx7625_reg_write(ctx, ctx->i2c.tcpc_client,
> +					  INTR_ALERT_1, 0xFF);
> +			anx7625_reg_write(ctx, ctx->i2c.rx_p0_client,
> +					  INTERFACE_CHANGE_INT, 0);
> +		}
> +
> +		anx7625_start_dp_work(ctx);
> +	}
> +
> +	if (WARN_ON(!atomic_read(&ctx->power_status)))
> +		return 0;
> +
> +	if (ctx->slimport_edid_p && ctx->slimport_edid_p->edid_block_num >= 0)
> +		return drm_add_edid_modes(connector,
> +					  (struct edid *)
> +					  &p_edid->edid_raw_data);
> +
> +	mutex_lock(&ctx->lock);
> +
> +	if (!ctx->slimport_edid_p)
> +		ctx->slimport_edid_p = kzalloc(sizeof(*ctx->slimport_edid_p),
> +					       GFP_KERNEL);

Add a check for NULL.

> +	p_edid = ctx->slimport_edid_p;
> +	p_edid->edid_block_num = sp_tx_edid_read(ctx, p_edid->edid_raw_data);
> +	if (p_edid->edid_block_num < 0) {
> +		DRM_ERROR("Failed to read EDID.\n");
> +		goto unlock;
> +	}
> +
> +	err = drm_connector_update_edid_property(connector,
> +						 (struct edid *)
> +						 &p_edid->edid_raw_data);
> +
> +	if (err) {
> +		DRM_ERROR("Failed to update EDID property: %d\n", err);
> +		goto unlock;
> +	}
> +
> +	num_modes = drm_add_edid_modes(connector,
> +				       (struct edid *)&p_edid->edid_raw_data);
> +
> +unlock:
> +	mutex_unlock(&ctx->lock);
> +
> +	return num_modes;
> +}
> +
> +static enum drm_mode_status
> +anx7625_connector_mode_valid(struct drm_connector *connector,
> +			     struct drm_display_mode *mode)
> +{
> +	struct anx7625_data *ctx = connector_to_anx7625(connector);
> +	struct device *dev = &ctx->client->dev;
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "drm modes valid verify\n");
> +
> +	if (mode->clock > 300000)
> +		return MODE_CLOCK_HIGH;
> +
> +	return MODE_OK;
> +}
> +
> +static struct drm_connector_helper_funcs anx7625_connector_helper_funcs = {
> +	.get_modes = anx7625_get_modes,
> +	.mode_valid = anx7625_connector_mode_valid,
> +};
> +
> +static enum drm_connector_status anx7625_detect(struct drm_connector *connector,
> +						bool force)
> +{
> +	struct anx7625_data *ctx = connector_to_anx7625(connector);
> +	struct device *dev = &ctx->client->dev;
> +
> +	if (!(ctx->hpd_status))

Remove extra parens.

> +		return connector_status_disconnected;
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "drm detect\n");
> +
> +	return connector_status_connected;
> +}
> +
> +static const struct drm_connector_funcs anx7625_connector_funcs = {
> +	.fill_modes = drm_helper_probe_single_connector_modes,
> +	.detect = anx7625_detect,
> +	.destroy = drm_connector_cleanup,
> +	.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 void anx7625_attach_dsi(struct anx7625_data *ctx)
> +{
> +	struct mipi_dsi_host *host;
> +	struct mipi_dsi_device *dsi;
> +	struct device *dev = &ctx->client->dev;
> +	const struct mipi_dsi_device_info info = {
> +		.type = "anx7625",
> +		.channel = ctx->pdata.dsi_channel,
> +		.node = NULL,
> +	};
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "attach dsi\n");
> +
> +	host = of_find_mipi_dsi_host_by_node(ctx->pdata.host_node);
> +	if (!host) {
> +		DRM_ERROR("failed to find dsi host.\n");
> +		return;

I feel like this should really return negative error codes.

> +	}
> +
> +	dsi = mipi_dsi_device_register_full(host, &info);
> +	if (IS_ERR(dsi)) {
> +		DRM_ERROR("failed to create dsi device.\n");
> +		return;
> +	}
> +
> +	dsi->lanes = ctx->pdata.dsi_lanes;
> +	dsi->format = MIPI_DSI_FMT_RGB888;
> +	dsi->mode_flags = MIPI_DSI_MODE_VIDEO	|
> +		MIPI_DSI_MODE_VIDEO_SYNC_PULSE	|
> +		MIPI_DSI_MODE_EOT_PACKET	|
> +		MIPI_DSI_MODE_VIDEO_HSE;
> +
> +	if (mipi_dsi_attach(dsi) < 0) {
> +		DRM_ERROR("failed to attach dsi to host.\n");
> +		mipi_dsi_device_unregister(dsi);
> +		return;
> +	}
> +
> +	ctx->dsi = dsi;
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "attach dsi succeeded.\n");
> +}
> +
> +static void anx7625_detach_dsi(struct anx7625_data *ctx)
> +{
> +	if (ctx->dsi) {
> +		mipi_dsi_detach(ctx->dsi);
> +		mipi_dsi_device_unregister(ctx->dsi);
> +	}
> +}
> +
> +static int anx7625_bridge_attach(struct drm_bridge *bridge)
> +{
> +	struct anx7625_data *ctx = bridge_to_anx7625(bridge);
> +	int err;
> +	struct device *dev = &ctx->client->dev;
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "drm attach\n");
> +	if (!bridge->encoder) {
> +		DRM_ERROR("Parent encoder object not found");
> +		return -ENODEV;
> +	}
> +
> +	err = drm_connector_init(bridge->dev, &ctx->connector,
> +				 &anx7625_connector_funcs,
> +				 DRM_MODE_CONNECTOR_DisplayPort);
> +	if (err) {
> +		DRM_ERROR("Failed to initialize connector: %d\n", err);
> +		return err;
> +	}
> +
> +	drm_connector_helper_add(&ctx->connector,
> +				 &anx7625_connector_helper_funcs);
> +
> +	err = drm_connector_register(&ctx->connector);
> +	if (err) {
> +		DRM_ERROR("Failed to register connector: %d\n", err);
> +		return err;
> +	}
> +
> +	ctx->connector.polled = DRM_CONNECTOR_POLL_HPD;
> +
> +	err = drm_connector_attach_encoder(&ctx->connector, bridge->encoder);
> +	if (err) {
> +		DRM_ERROR("Failed to link up connector to encoder: %d\n", err);
> +		drm_connector_unregister(&ctx->connector);
> +		return err;
> +	}
> +
> +	anx7625_attach_dsi(ctx);
> +
> +	ctx->bridge_attached = 1;
> +
> +	return 0;
> +}
> +
> +static enum drm_mode_status
> +anx7625_bridge_mode_valid(struct drm_bridge *bridge,
> +			  const struct drm_display_mode *mode)
> +{
> +	struct anx7625_data *ctx = bridge_to_anx7625(bridge);
> +	struct device *dev = &ctx->client->dev;
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "drm mode checking\n");
> +
> +	/* Max 1200p at 5.4 Ghz, one lane, pixel clock 300M */
> +	if (mode->clock > 300000) {
> +		DRM_DEV_DEBUG_DRIVER(dev,
> +				     "drm mode invalid, pixelclock too high.\n");
> +		return MODE_CLOCK_HIGH;
> +	}
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "drm mode valid.\n");
> +	return MODE_OK;
> +}
> +
> +static void anx7625_bridge_mode_set(struct drm_bridge *bridge,
> +				    const struct drm_display_mode *old_mode,
> +				    const struct drm_display_mode *mode)
> +{
> +	struct anx7625_data *ctx = bridge_to_anx7625(bridge);
> +	struct device *dev = &ctx->client->dev;
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "drm mode set\n");

You can get better information with ftrace.

> +
> +	if (WARN_ON(!atomic_read(&ctx->power_status)))
> +		return;
> +
> +	mutex_lock(&ctx->lock);
> +
> +	ctx->dt.pixelclock.min = mode->clock;
> +	ctx->dt.hactive.min = mode->hdisplay;
> +	ctx->dt.hsync_len.min = mode->hsync_end - mode->hsync_start;
> +	ctx->dt.hfront_porch.min = mode->hsync_start - mode->hdisplay;
> +	ctx->dt.hback_porch.min = mode->htotal - mode->hsync_end;
> +	ctx->dt.vactive.min = mode->vdisplay;
> +	ctx->dt.vsync_len.min = mode->vsync_end - mode->vsync_start;
> +	ctx->dt.vfront_porch.min = mode->vsync_start - mode->vdisplay;
> +	ctx->dt.vback_porch.min = mode->vtotal - mode->vsync_end;
> +
> +	ctx->display_timing_valid = 1;
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "pixelclock(%d).\n", ctx->dt.pixelclock.min);
> +	DRM_DEV_DEBUG_DRIVER(dev, "hactive(%d), hsync(%d), hfp(%d), hbp(%d)\n",
> +			     ctx->dt.hactive.min,
> +			     ctx->dt.hsync_len.min,
> +			     ctx->dt.hfront_porch.min,
> +			     ctx->dt.hback_porch.min);
> +	DRM_DEV_DEBUG_DRIVER(dev, "vactive(%d), vsync(%d), vfp(%d), vbp(%d)\n",
> +			     ctx->dt.vactive.min,
> +			     ctx->dt.vsync_len.min,
> +			     ctx->dt.vfront_porch.min,
> +			     ctx->dt.vback_porch.min);
> +	DRM_DEV_DEBUG_DRIVER(dev, "hdisplay(%d),hsync_start(%d).\n",
> +			     mode->hdisplay,
> +			     mode->hsync_start);
> +	DRM_DEV_DEBUG_DRIVER(dev, "hsync_end(%d),htotal(%d).\n",
> +			     mode->hsync_end,
> +			     mode->htotal);
> +	DRM_DEV_DEBUG_DRIVER(dev, "vdisplay(%d),vsync_start(%d).\n",
> +			     mode->vdisplay,
> +			     mode->vsync_start);
> +	DRM_DEV_DEBUG_DRIVER(dev, "vsync_end(%d),vtotal(%d).\n",
> +			     mode->vsync_end,
> +			     mode->vtotal);
> +
> +	mutex_unlock(&ctx->lock);
> +}
> +
> +static void anx7625_bridge_enable(struct drm_bridge *bridge)
> +{
> +	struct anx7625_data *ctx = bridge_to_anx7625(bridge);
> +	struct device *dev = &ctx->client->dev;
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "drm enable\n");

ftrace.

> +
> +	if (WARN_ON(!atomic_read(&ctx->power_status)))
> +		return;
> +
> +	mutex_lock(&ctx->lock);
> +
> +	anx7625_dp_start(ctx);
> +
> +	mutex_unlock(&ctx->lock);
> +}
> +
> +static void anx7625_bridge_disable(struct drm_bridge *bridge)
> +{
> +	struct anx7625_data *ctx = bridge_to_anx7625(bridge);
> +	struct device *dev = &ctx->client->dev;
> +
> +	if (WARN_ON(!atomic_read(&ctx->power_status)))
> +		return;
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "drm disable\n");

ftrace.

> +	mutex_lock(&ctx->lock);
> +
> +	anx7625_dp_stop(ctx);
> +
> +	if (ctx->pdata.internal_pannel &&
> +	    ctx->pdata.low_power_mode &&
> +	    (atomic_read(&ctx->power_status))) {
> +		anx7625_stop_dp_work(ctx);
> +		anx7625_power_standby(ctx);
> +		atomic_set(&ctx->power_status, 0);
> +	}
> +
> +	mutex_unlock(&ctx->lock);
> +}
> +
> +static const struct drm_bridge_funcs anx7625_bridge_funcs = {
> +	.attach = anx7625_bridge_attach,
> +	.disable = anx7625_bridge_disable,
> +	.mode_valid = anx7625_bridge_mode_valid,
> +	.mode_set = anx7625_bridge_mode_set,
> +	.enable = anx7625_bridge_enable,
> +};
> +
> +static int anx7625_register_i2c_dummy_clients(struct anx7625_data *ctx,
> +					      struct i2c_client *client)
> +{
> +	ctx->i2c.tx_p0_client = i2c_new_dummy(client->adapter,
> +					     TX_P0_ADDR >> 1);
> +	ctx->i2c.tx_p1_client = i2c_new_dummy(client->adapter,
> +					      TX_P1_ADDR >> 1);
> +	ctx->i2c.tx_p2_client = i2c_new_dummy(client->adapter,
> +					      TX_P2_ADDR >> 1);
> +
> +	ctx->i2c.rx_p0_client = i2c_new_dummy(client->adapter,
> +					      RX_P0_ADDR >> 1);
> +	ctx->i2c.rx_p1_client = i2c_new_dummy(client->adapter,
> +					      RX_P1_ADDR >> 1);
> +	ctx->i2c.rx_p2_client = i2c_new_dummy(client->adapter,
> +					      RX_P2_ADDR >> 1);
> +
> +	ctx->i2c.tcpc_client = i2c_new_dummy(client->adapter,
> +					     TCPC_INTERFACE_ADDR >> 1);
> +
> +	if ((!ctx->i2c.tx_p0_client |
> +	     !ctx->i2c.tx_p1_client |
> +	     !ctx->i2c.tx_p2_client |
> +	     !ctx->i2c.rx_p0_client |
> +	     !ctx->i2c.rx_p1_client |
> +	     !ctx->i2c.rx_p2_client |
> +	     !ctx->i2c.tcpc_client) != 0)

This is too complicated.  Don't return 1 on failure.  Every function
should clean up it's own partial allocations.

	if (!ctx->i2c.tx_p0_client ||
	    !ctx->i2c.tx_p1_client ||
		...
	    !ctx->i2c.tcpc_client) {
		anx7625_unregister_i2c_dummy_clients(ctx);
		return -ENOMEM;
	}

> +		return 1;
> +
> +	return 0;
> +}
> +
> +static void anx7625_unregister_i2c_dummy_clients(struct anx7625_data *ctx)
> +{
> +	i2c_unregister_device(ctx->i2c.tx_p0_client);
> +	i2c_unregister_device(ctx->i2c.tx_p1_client);
> +	i2c_unregister_device(ctx->i2c.tx_p2_client);
> +	i2c_unregister_device(ctx->i2c.rx_p1_client);
> +	i2c_unregister_device(ctx->i2c.rx_p2_client);
> +	i2c_unregister_device(ctx->i2c.rx_p3_client);
> +	i2c_unregister_device(ctx->i2c.tcpc_client);
> +}
> +
> +static int anx7625_i2c_probe(struct i2c_client *client,
> +			     const struct i2c_device_id *id)
> +{
> +	struct anx7625_data *platform;
> +	struct anx7625_platform_data *pdata;
> +	int ret = 0;
> +	struct device *dev = &client->dev;
> +
> +	if (!i2c_check_functionality(client->adapter,
> +				     I2C_FUNC_SMBUS_I2C_BLOCK)) {
> +		DRM_DEV_ERROR(dev, "anx7625's i2c bus doesn't support\n");
> +		ret = -ENODEV;
> +		goto exit;

return -ENODEV;

> +	}
> +
> +	platform = kzalloc(sizeof(*platform), GFP_KERNEL);
> +	if (!platform) {
> +		DRM_DEV_ERROR(dev, "failed to allocate driver data\n");
> +		ret = -ENOMEM;
> +		goto exit;

Use devm_kzalloc()?  return -ENOMEM;

> +	}
> +
> +	pdata = &platform->pdata;
> +
> +	/* device tree parsing function call */
> +	ret = anx7625_parse_dt(&client->dev, pdata);
> +	if (ret != 0)	/* if occurs error */

Only use == 0 when you are talking about numbers as in if (size == 0) or
if (cnt == 0) or for strcmp() == 0.  Here zero is the absence of errors
so it should be "if (ret) ".

> +		goto err0;

goto free_platfrom;

> +
> +	/* to access global platform data */
> +	platform->client = client;
> +	i2c_set_clientdata(client, platform);
> +
> +	if (platform->pdata.extcon_supported) {
> +		/* get extcon device from DTS */
> +		platform->extcon = extcon_get_edev_by_phandle(&client->dev, 0);
> +		if (PTR_ERR(platform->extcon) == -EPROBE_DEFER)
> +			goto err0;
> +		if (IS_ERR(platform->extcon)) {
> +			DRM_DEV_ERROR(&client->dev,
> +				      "can not get extcon device!");
> +			goto err0;
> +		}
> +
> +		ret = anx7625_extcon_notifier_init(platform);
> +		if (ret < 0)
> +			goto err0;
> +	}
> +
> +	atomic_set(&platform->power_status, 0);
> +
> +	mutex_init(&platform->lock);
> +
> +	ret = anx7625_init_gpio(platform);
> +	if (ret) {
> +		DRM_DEV_ERROR(dev, "failed to initialize gpio\n");
> +		goto err0;
> +	}
> +
> +	INIT_WORK(&platform->work, anx7625_work_func);
> +
> +	platform->workqueue = create_workqueue("anx7625_work");
> +	if (!platform->workqueue) {
> +		DRM_DEV_ERROR(dev, "failed to create work queue\n");
> +		ret = -ENOMEM;
> +		goto err1;

goto err_free_gpio;

> +	}
> +
> +	if (platform->pdata.gpio_intr_hpd) {
> +		platform->pdata.hpd_irq =
> +			gpio_to_irq(platform->pdata.gpio_intr_hpd);
> +		if (platform->pdata.hpd_irq < 0) {
> +			DRM_DEV_ERROR(dev, "failed to get gpio irq\n");
> +			goto err1;

Leak.  goto err_destroy_wq;

> +		}
> +
> +		ret = request_threaded_irq(platform->pdata.hpd_irq,
> +					   NULL, anx7625_intr_hpd_isr,
> +					   IRQF_TRIGGER_FALLING |
> +					   IRQF_TRIGGER_RISING |
> +					   IRQF_ONESHOT,
> +					   "anx7625-hpd", platform);
> +		if (ret < 0) {
> +			DRM_DEV_ERROR(dev, "failed to request irq\n");
> +			goto err2;


goto free_workqueue;

> +		}
> +
> +		ret = irq_set_irq_wake(platform->pdata.hpd_irq, 1);
> +		if (ret < 0) {
> +			DRM_DEV_ERROR(dev, "Request irq for hpd");
> +			DRM_DEV_ERROR(dev, "interrupt wake set fail\n");
> +			goto err2;

Leak?  goto err_free_irq?


> +		}
> +
> +		ret = enable_irq_wake(platform->pdata.hpd_irq);
> +		if (ret < 0) {
> +			DRM_DEV_ERROR(dev, "Enable irq for HPD");
> +			DRM_DEV_ERROR(dev, "interrupt wake enable fail\n");
> +			goto err2;

Leak?

> +		}
> +	}
> +
> +	if (anx7625_register_i2c_dummy_clients(platform, client) != 0) {

Now that anx7625_register_i2c_dummy_clients() returns a valid error
code we should preserve it.  No need to release the partially allocated
dummy clients because it either allocates everything or it doesn't
allocate anything.

	ret = anx7625_register_i2c_dummy_clients();
	if (ret)
		goto err_free_irq;

> +		ret = -ENOMEM;
> +		DRM_ERROR("Failed to reserve I2C bus.\n");
> +		goto err3;
> +	}
> +
> +	if (platform->pdata.low_power_mode == 0) {
> +		anx7625_disable_pd_protocol(platform);
> +		atomic_set(&platform->power_status, 1);
> +	}
> +
> +	/* add work function */
> +	queue_work(platform->workqueue, &platform->work);
> +
> +	platform->bridge.funcs = &anx7625_bridge_funcs;
> +#if IS_ENABLED(CONFIG_OF)
> +	platform->bridge.of_node = client->dev.of_node;
> +#endif

We can get rid of the ifdef.

	if (IS_ENABLED(CONFIG_OF))
		platform->bridge.of_node = client->dev.of_node;


> +	drm_bridge_add(&platform->bridge);
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "probe done\n");
> +	goto exit;

return 0;

> +
> +err3:
> +	anx7625_unregister_i2c_dummy_clients(platform);
> +err2:
> +	if (platform->pdata.gpio_intr_hpd)
> +		free_irq(platform->pdata.hpd_irq, platform);
> +err1:
> +	anx7625_free_gpio(platform);
> +	destroy_workqueue(platform->workqueue);
> +err0:
> +	kfree(platform);
> +exit:
> +	return ret;

err_free_irq:
	if (platform->pdata.gpio_intr_hpd)
		free_irq(platform->pdata.hpd_irq, platform);
err_destroy_wq:
	destroy_workqueue(platform->workqueue);
err_free_gpio:
	anx7625_free_gpio(platform);
err_free_platform:
	kfree(platform);

	return ret;


> +}
> +
> +static int anx7625_i2c_remove(struct i2c_client *client)
> +{
> +	struct anx7625_data *platform = i2c_get_clientdata(client);
> +
> +	drm_bridge_remove(&platform->bridge);
> +
> +	if (platform->pdata.gpio_intr_hpd)
> +		free_irq(platform->pdata.hpd_irq, platform);
> +
> +	destroy_workqueue(platform->workqueue);
> +
> +	if (platform->pdata.extcon_supported) {
> +		devm_extcon_unregister_notifier(&platform->client->dev,
> +						platform->extcon,
> +						EXTCON_DISP_DP,
> +						&platform->event_nb);
> +		flush_work(&platform->extcon_wq);
> +	}
> +
> +	anx7625_detach_dsi(platform);
> +
> +	if (platform->bridge_attached)
> +		drm_connector_unregister(&platform->connector);
> +

We don't call anx7625_attach_dis() or drm_connector_register() during
probe so it's weird that we are doing it in remove.

> +	anx7625_unregister_i2c_dummy_clients(platform);

This should done between drm_bridge_remove() and free_irq() so that
we unwind in the opposite/mirror order of how we probe().

> +
> +	anx7625_free_gpio(platform);
> +
> +	kfree(platform);
> +	return 0;
> +}

regards,
dan carpenter