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 <x...@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
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