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

From: Robert Foss <robert.foss@linaro.org>
To: Xin Ji <xji@analogixsemi.com>
Cc: Nicolas Boichat <drinkcat@google.com>,
	Andrzej Hajda <a.hajda@samsung.com>,
	Neil Armstrong <narmstrong@baylibre.com>,
	Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
	Jonas Karlman <jonas@kwiboo.se>,
	Jernej Skrabec <jernej.skrabec@siol.net>,
	Dan Carpenter <dan.carpenter@oracle.com>,
	David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
	Boris Brezillon <boris.brezillon@collabora.com>,
	Sam Ravnborg <sam@ravnborg.org>,
	Hsin-Yi Wang <hsinyi@chromium.org>, Torsten Duwe <duwe@lst.de>,
	Vasily Khoruzhick <anarsoul@gmail.com>,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	Sheng Pan <span@analogixsemi.com>,
	Bernie Liang <bliang@analogixsemi.com>,
	Zhen Li <zhenli@analogixsemi.com>,
	dri-devel <dri-devel@lists.freedesktop.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	devel@driverdev.osuosl.org
Subject: Re: [PATCH 1/1] drm/bridge: anx7625: send DPCD command to downstream
Date: Fri, 9 Apr 2021 11:05:54 +0200	[thread overview]
Message-ID: <CAG3jFyuisQe1RZXx8GpQjwPczak+PBXA084i9euuREeV_w55Rw@mail.gmail.com> (raw)
In-Reply-To: <18ec1a440eb71e4f91c0932cd0fadddd2e9a4c0f.1617937551.git.xji@analogixsemi.com>

Hey Xin,

On Fri, 9 Apr 2021 at 07:35, Xin Ji <xji@analogixsemi.com> wrote:
>
> Send DPCD command to downstream before anx7625 power down,
> tell downstream into standby mode.
>
> Signed-off-by: Xin Ji <xji@analogixsemi.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@linaro.org>