[PATCH] drm: rz-du: Support panels connected directly to the DPAD output

[Tommaso Merciai]

Hi Biju,
Thanks for your patch.

On Thu, May 08, 2025 at 10:50:35AM +0100, Biju Das wrote:
> From: hienhuynh <hien.huynh.px at renesas.com>
> 
> This patch is based on the commit 73eb5476df72 ("drm: rcar-du: Support
> panels connected directly to the DPAD outputs").
> 
> The RZ DU driver assumes that a bridge is always connected to the DU
> output. This is valid for the HDMI output, but the DPAD output 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 output is 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: hienhuynh <hien.huynh.px at renesas.com>
> Signed-off-by: Biju Das <biju.das.jz at bp.renesas.com>

Tested on RZ/G3E with the following pipeline:

DU -> adv7513 -> HDMI panel

Reviewed-by: Tommaso Merciai <tommaso.merciai.xr at bp.renesas.com>
Tested-by: Tommaso Merciai <tommaso.merciai.xr at bp.renesas.com>

Thanks & Regards,
Tommaso

> ---
>  .../gpu/drm/renesas/rz-du/rzg2l_du_encoder.c  | 44 +++++++++++++++++--
>  1 file changed, 40 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/renesas/rz-du/rzg2l_du_encoder.c b/drivers/gpu/drm/renesas/rz-du/rzg2l_du_encoder.c
> index 564ab4cb3d37..5e6dd16705e6 100644
> --- a/drivers/gpu/drm/renesas/rz-du/rzg2l_du_encoder.c
> +++ b/drivers/gpu/drm/renesas/rz-du/rzg2l_du_encoder.c
> @@ -22,6 +22,26 @@
>   * Encoder
>   */
>  
> +static unsigned int rzg2l_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(ports);
> +
> +	return num_ports;
> +}
> +
>  static const struct drm_encoder_funcs rzg2l_du_encoder_funcs = {
>  };
>  
> @@ -50,10 +70,26 @@ int rzg2l_du_encoder_init(struct rzg2l_du_device  *rcdu,
>  	struct drm_bridge *bridge;
>  	int ret;
>  
> -	/* Locate the DRM bridge from the DT node. */
> -	bridge = of_drm_find_bridge(enc_node);
> -	if (!bridge)
> -		return -EPROBE_DEFER;
> +	/*
> +	 * Locate the DRM bridge from the DT node. For the DPAD outputs, if the
> +	 * DT node has a single port, assume that it describes a panel and
> +	 * create a panel bridge.
> +	 */
> +	if (output == RZG2L_DU_OUTPUT_DPAD0 && rzg2l_du_encoder_count_ports(enc_node) == 1) {
> +		struct drm_panel *panel = of_drm_find_panel(enc_node);
> +
> +		if (IS_ERR(panel))
> +			return PTR_ERR(panel);
> +
> +		bridge = devm_drm_panel_bridge_add_typed(rcdu->dev, panel,
> +							 DRM_MODE_CONNECTOR_DPI);
> +		if (IS_ERR(bridge))
> +			return PTR_ERR(bridge);
> +	} else {
> +		bridge = of_drm_find_bridge(enc_node);
> +		if (!bridge)
> +			return -EPROBE_DEFER;
> +	}
>  
>  	dev_dbg(rcdu->dev, "initializing encoder %pOF for output %s\n",
>  		enc_node, rzg2l_du_output_name(output));
> -- 
> 2.43.0
>