[PATCH] drm: rcar-du: Support panels connected directly to the DPAD outputs

[Key, Kevin]

Tested and confirmed the correct operation the patched driver on the
Renesas r8a7796-m3ulcb platform.

Tested-by: Kevin Key <kevin.key at gentex.com>

On Sat, 2019-03-02 at 18:17 +0200, Laurent Pinchart wrote:
> The R-Car DU driver assumes that a bridge is always connected to the
> DU
> output. This is valid for the LVDS and HDMI outputs, but the DPAD
> outputs can be connected directly to a panel, in which case no bridge
> is
> available.
>
> To support this use case, detect whether the entities connected to
> the
> DU DPAD outputs are encoders or panels based on the number of ports
> of
> their DT node, and retrieve the corresponding type of DRM objects.
> For
> panels, additionally create panel bridge instances.
>
> Signed-off-by: Laurent Pinchart <
> laurent.pinchart+renesas at ideasonboard.com>
> ---
>  drivers/gpu/drm/rcar-du/rcar_du_encoder.c | 54 ++++++++++++++++++++-
> --
>  1 file changed, 48 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_encoder.c
> b/drivers/gpu/drm/rcar-du/rcar_du_encoder.c
> index 8ee4e762f4e5..595ecfa1ff0e 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_du_encoder.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_encoder.c
> @@ -28,13 +28,33 @@ static const struct drm_encoder_funcs
> encoder_funcs = {
>         .destroy = drm_encoder_cleanup,
>  };
>
> +static unsigned int rcar_du_encoder_count_ports(struct device_node
> *node)
> +{
> +       struct device_node *ports;
> +       struct device_node *port;
> +       unsigned int num_ports = 0;
> +
> +       ports = of_get_child_by_name(node, "ports");
> +       if (!ports)
> +               ports = of_node_get(node);
> +
> +       for_each_child_of_node(ports, port) {
> +               if (of_node_name_eq(port, "port"))
> +                       num_ports++;
> +       }
> +
> +       of_node_put(node);
> +
> +       return num_ports;
> +}
> +
>  int rcar_du_encoder_init(struct rcar_du_device *rcdu,
>                          enum rcar_du_output output,
>                          struct device_node *enc_node)
>  {
>         struct rcar_du_encoder *renc;
>         struct drm_encoder *encoder;
> -       struct drm_bridge *bridge = NULL;
> +       struct drm_bridge *bridge;
>         int ret;
>
>         renc = devm_kzalloc(rcdu->dev, sizeof(*renc), GFP_KERNEL);
> @@ -48,11 +68,33 @@ int rcar_du_encoder_init(struct rcar_du_device
> *rcdu,
>         dev_dbg(rcdu->dev, "initializing encoder %pOF for output
> %u\n",
>                 enc_node, output);
>
> -       /* Locate the DRM bridge from the encoder DT node. */
> -       bridge = of_drm_find_bridge(enc_node);
> -       if (!bridge) {
> -               ret = -EPROBE_DEFER;
> -               goto done;
> +       /*
> +        * Locate the DRM bridge from the DT node. For the DPAD
> outputs, if the
> +        * DT node has a single port, consider it describes a panel
> and create a
> +        * panel bridge.
> +        */
> +       if ((output == RCAR_DU_OUTPUT_DPAD0 ||
> +            output == RCAR_DU_OUTPUT_DPAD1) &&
> +           rcar_du_encoder_count_ports(enc_node) == 1) {
> +               struct drm_panel *panel =
> of_drm_find_panel(enc_node);
> +
> +               if (IS_ERR(panel)) {
> +                       ret = PTR_ERR(panel);
> +                       goto done;
> +               }
> +
> +               bridge = devm_drm_panel_bridge_add(rcdu->dev, panel,
> +                                                  DRM_MODE_CONNECTOR
> _DPI);
> +               if (IS_ERR(bridge)) {
> +                       ret = PTR_ERR(bridge);
> +                       goto done;
> +               }
> +       } else {
> +               bridge = of_drm_find_bridge(enc_node);
> +               if (!bridge) {
> +                       ret = -EPROBE_DEFER;
> +                       goto done;
> +               }
>         }
>
>         ret = drm_encoder_init(rcdu->ddev, encoder, &encoder_funcs,
> --
> Regards,
>
> Laurent Pinchart
>
>
>
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