Date:   Fri, 9 Apr 2021 11:05:54 +0200
From:   Robert Foss <robert.foss@...aro.org>
To:     Xin Ji <xji@...logixsemi.com>
Cc:     Nicolas Boichat <drinkcat@...gle.com>,
        Andrzej Hajda <a.hajda@...sung.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...l.net>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Boris Brezillon <boris.brezillon@...labora.com>,
        Sam Ravnborg <sam@...nborg.org>,
        Hsin-Yi Wang <hsinyi@...omium.org>, Torsten Duwe <duwe@....de>,
        Vasily Khoruzhick <anarsoul@...il.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Sheng Pan <span@...logixsemi.com>,
        Bernie Liang <bliang@...logixsemi.com>,
        Zhen Li <zhenli@...logixsemi.com>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        devel@...verdev.osuosl.org
Subject: Re: [PATCH 1/1] drm/bridge: anx7625: send DPCD command to downstream

Hey Xin,


On Fri, 9 Apr 2021 at 07:35, Xin Ji <xji@...logixsemi.com> wrote:
>
> Send DPCD command to downstream before anx7625 power down,
> tell downstream into standby mode.
>
> Signed-off-by: Xin Ji <xji@...logixsemi.com>
> ---
>  drivers/gpu/drm/bridge/analogix/anx7625.c | 75 +++++++++++++++++++++++
>  1 file changed, 75 insertions(+)
>
> diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.c b/drivers/gpu/drm/bridge/analogix/anx7625.c
> index 65cc05982f82..53d2f0d0ee30 100644
> --- a/drivers/gpu/drm/bridge/analogix/anx7625.c
> +++ b/drivers/gpu/drm/bridge/analogix/anx7625.c
> @@ -124,6 +124,23 @@ 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)
> +               DRM_DEV_ERROR(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)
> @@ -195,6 +212,55 @@ static int wait_aux_op_finish(struct anx7625_data *ctx)
>         return val;
>  }
>
> +static int anx7625_aux_dpcd_write(struct anx7625_data *ctx,
> +                                 u8 addrh, u8 addrm, u8 addrl,
> +                                 u8 len, u8 *buf)
> +{
> +       struct device *dev = &ctx->client->dev;
> +       int ret;
> +       u8 cmd;
> +
> +       if (len > MAX_DPCD_BUFFER_SIZE) {
> +               DRM_DEV_ERROR(dev, "exceed aux buffer len.\n");
> +               return -EINVAL;
> +       }
> +
> +       cmd = ((len - 1) << 4) | 0x08;
> +
> +       /* Set command and length */
> +       ret = anx7625_reg_write(ctx, ctx->i2c.rx_p0_client,
> +                               AP_AUX_COMMAND, cmd);
> +
> +       /* Set aux access address */
> +       ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p0_client,
> +                                AP_AUX_ADDR_7_0, addrl);
> +       ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p0_client,
> +                                AP_AUX_ADDR_15_8, addrm);
> +       ret |= anx7625_write_and(ctx, ctx->i2c.rx_p0_client,
> +                                AP_AUX_ADDR_19_16, addrh);
> +
> +       /* Set write data */
> +       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);
> +       if (ret < 0) {
> +               DRM_DEV_ERROR(dev, "cannot access aux related register.\n");
> +               return -EIO;
> +       }
> +
> +       usleep_range(2000, 2100);
> +
> +       ret = wait_aux_op_finish(ctx);
> +       if (ret) {
> +               DRM_DEV_ERROR(dev, "aux IO error: wait aux op finish.\n");
> +               return ret;
> +       }
> +
> +       return 0;
> +}
> +
>  static int anx7625_video_mute_control(struct anx7625_data *ctx,
>                                       u8 status)
>  {
> @@ -617,6 +683,7 @@ 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");
>
> @@ -628,8 +695,16 @@ 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);
> +
> +       DRM_DEV_DEBUG_DRIVER(dev, "notify downstream enter into standby\n");
> +
> +       /* Downstream monitor enter into standby mode */
> +       data = 2;
> +       ret |= anx7625_aux_dpcd_write(ctx, 0x00, 0x06, 0x00, 1, &data);
>         if (ret < 0)
>                 DRM_DEV_ERROR(dev, "IO error : mute video fail\n");
> +
> +       return;
>  }

Reviewed-by: Robert Foss <robert.foss@...aro.org>

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