Re: [PATCH v1] drm/bridge: lt8912b: Add hot plug detection

[Robert Foss <robert.foss@xxxxxxxxxx>]

On Mon, 28 Nov 2022 at 12:23, Francesco Dolcini <francesco@xxxxxxxxxx> wrote:
>
> From: Stefan Eichenberger <stefan.eichenberger@xxxxxxxxxxx>
>
> Enable hot plug detection when it is available on the HDMI port.
> Without this connecting to a different monitor with incompatible timing
> before the 10 seconds poll period will lead to a broken display output.
>
> Fixes: 30e2ae943c26 ("drm/bridge: Introduce LT8912B DSI to HDMI bridge")
> Signed-off-by: Stefan Eichenberger <stefan.eichenberger@xxxxxxxxxxx>
> Signed-off-by: Francesco Dolcini <francesco.dolcini@xxxxxxxxxxx>
> ---
>  drivers/gpu/drm/bridge/lontium-lt8912b.c | 21 +++++++++++++++++++--
>  1 file changed, 19 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/lontium-lt8912b.c b/drivers/gpu/drm/bridge/lontium-lt8912b.c
> index a98efef0ba0e..5f0c9cd2a970 100644
> --- a/drivers/gpu/drm/bridge/lontium-lt8912b.c
> +++ b/drivers/gpu/drm/bridge/lontium-lt8912b.c
> @@ -517,14 +517,27 @@ static int lt8912_attach_dsi(struct lt8912 *lt)
>         return 0;
>  }
>
> +static void lt8912_bridge_hpd_cb(void *data, enum drm_connector_status status)
> +{
> +       struct lt8912 *lt = data;
> +
> +       if (lt->bridge.dev)
> +               drm_helper_hpd_irq_event(lt->bridge.dev);
> +}
> +
>  static int lt8912_bridge_connector_init(struct drm_bridge *bridge)
>  {
>         int ret;
>         struct lt8912 *lt = bridge_to_lt8912(bridge);
>         struct drm_connector *connector = &lt->connector;
>
> -       connector->polled = DRM_CONNECTOR_POLL_CONNECT |
> -                           DRM_CONNECTOR_POLL_DISCONNECT;
> +       if (lt->hdmi_port->ops & DRM_BRIDGE_OP_HPD) {
> +               drm_bridge_hpd_enable(lt->hdmi_port, lt8912_bridge_hpd_cb, lt);
> +               connector->polled = DRM_CONNECTOR_POLL_HPD;
> +       } else {
> +               connector->polled = DRM_CONNECTOR_POLL_CONNECT |
> +                                   DRM_CONNECTOR_POLL_DISCONNECT;
> +       }
>
>         ret = drm_connector_init(bridge->dev, connector,
>                                  &lt8912_connector_funcs,
> @@ -578,6 +591,10 @@ static void lt8912_bridge_detach(struct drm_bridge *bridge)
>
>         if (lt->is_attached) {
>                 lt8912_hard_power_off(lt);
> +
> +               if (lt->hdmi_port->ops & DRM_BRIDGE_OP_HPD)
> +                       drm_bridge_hpd_disable(lt->hdmi_port);
> +
>                 drm_connector_unregister(&lt->connector);
>                 drm_connector_cleanup(&lt->connector);
>         }
> --
> 2.25.1
>


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

Snoozing this patch, will apply it in a few days if no issues are found.