Re: [PATCH v3 1/1] drm/bridge: anx7625: send DPCD command to downstream

[Hsin-Yi Wang]

On Tue, Jan 11, 2022 at 5:06 PM Xin Ji <xji@xxxxxxxxxxxxxxxx> wrote:
>
> Send DPCD command to downstream before anx7625 power down,
> let downstream monitor enter into standby mode.
>
> Signed-off-by: Xin Ji <xji@xxxxxxxxxxxxxxxx>
> ---
>  drivers/gpu/drm/bridge/analogix/anx7625.c | 42 +++++++++++++++++++----
>  1 file changed, 35 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.c b/drivers/gpu/drm/bridge/analogix/anx7625.c
> index 33383f83255d..0b858c78abe8 100644
> --- a/drivers/gpu/drm/bridge/analogix/anx7625.c
> +++ b/drivers/gpu/drm/bridge/analogix/anx7625.c
> @@ -129,6 +129,23 @@ static int anx7625_reg_write(struct anx7625_data *ctx,
>         return ret;
>  }
>
> +static int anx7625_reg_block_write(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_write_i2c_block_data(client, reg_addr, len, buf);
> +       if (ret < 0)
> +               dev_err(dev, "write i2c block failed 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)
> @@ -214,8 +231,8 @@ static int wait_aux_op_finish(struct anx7625_data *ctx)
>         return 0;
>  }
>
> -static int anx7625_aux_dpcd_read(struct anx7625_data *ctx,
> -                                u32 address, u8 len, u8 *buf)
> +static int anx7625_aux_dpcd_trans(struct anx7625_data *ctx, u8 op,
> +                                 u32 address, u8 len, u8 *buf)
>  {
>         struct device *dev = &ctx->client->dev;
>         int ret;
> @@ -231,8 +248,7 @@ static int anx7625_aux_dpcd_read(struct anx7625_data *ctx,
>         addrm = (address >> 8) & 0xFF;
>         addrh = (address >> 16) & 0xFF;
>
> -       cmd = DPCD_CMD(len, DPCD_READ);
> -       cmd = ((len - 1) << 4) | 0x09;
> +       cmd = DPCD_CMD(len, op);
>
>         /* Set command and length */
>         ret = anx7625_reg_write(ctx, ctx->i2c.rx_p0_client,
> @@ -246,6 +262,9 @@ static int anx7625_aux_dpcd_read(struct anx7625_data *ctx,
>         ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p0_client,
>                                  AP_AUX_ADDR_19_16, addrh);
>
> +       if (op == DPCD_WRITE)
> +               ret |= anx7625_reg_block_write(ctx, ctx->i2c.rx_p0_client,
> +                                              AP_AUX_BUFF_START, len, buf);
>         /* Enable aux access */
>         ret |= anx7625_write_or(ctx, ctx->i2c.rx_p0_client,
>                                 AP_AUX_CTRL_STATUS, AP_AUX_CTRL_OP_EN);
> @@ -255,14 +274,17 @@ static int anx7625_aux_dpcd_read(struct anx7625_data *ctx,
>                 return -EIO;
>         }
>
> -       usleep_range(2000, 2100);
> -
>         ret = wait_aux_op_finish(ctx);
>         if (ret) {
>                 dev_err(dev, "aux IO error: wait aux op finish.\n");
>                 return ret;
>         }
>
> +       /* Write done */
> +       if (op == DPCD_WRITE)
> +               return 0;
> +
> +       /* Read done, read out dpcd data */
>         ret = anx7625_reg_block_read(ctx, ctx->i2c.rx_p0_client,
>                                      AP_AUX_BUFF_START, len, buf);
>         if (ret < 0) {
> @@ -845,7 +867,7 @@ static int anx7625_hdcp_enable(struct anx7625_data *ctx)
>         }
>
>         /* Read downstream capability */
> -       anx7625_aux_dpcd_read(ctx, 0x68028, 1, &bcap);
> +       anx7625_aux_dpcd_trans(ctx, DPCD_READ, 0x68028, 1, &bcap);
>         if (!(bcap & 0x01)) {
>                 pr_warn("downstream not support HDCP 1.4, cap(%x).\n", bcap);
>                 return 0;
> @@ -918,6 +940,7 @@ static void anx7625_dp_stop(struct anx7625_data *ctx)
>  {
>         struct device *dev = &ctx->client->dev;
>         int ret;
> +       u8 data;
>
>         DRM_DEV_DEBUG_DRIVER(dev, "stop dp output\n");
>
> @@ -929,6 +952,11 @@ static void anx7625_dp_stop(struct anx7625_data *ctx)
>         ret |= anx7625_write_and(ctx, ctx->i2c.tx_p2_client, 0x08, 0x7f);
>
>         ret |= anx7625_video_mute_control(ctx, 1);
> +
> +       dev_dbg(dev, "notify downstream enter into standby\n");
> +       /* Downstream monitor enter into standby mode */
> +       data = 2;
> +       ret |= anx7625_aux_dpcd_trans(ctx, DPCD_WRITE, 0x000600, 1, &data);

Is DPCD_READ/WRITE used for the same purpose as
DP_AUX_NATIVE_WRITE/READ? If so, maybe you can just use
DP_AUX_NATIVE_WRITE/READ and we don't need to define these values
again in the driver?

>         if (ret < 0)
>                 DRM_DEV_ERROR(dev, "IO error : mute video fail\n");
>
> --
> 2.25.1
>