Re: [PATCH v3 12/19] drm/mcde: dsi: don't create a panel_bridge

[Maxime Ripard <mripard@kernel.org>]

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On Wed, Sep 16, 2026 at 03:45:36PM +0200, Luca Ceresoli wrote:
> Now a panel_bridge is automatically created for every drm_panel and the
> panel-bridge API is just a deprecated wrapper to access it.
> 
> Update and simplify the code by just getting a reference to the
> already-existing bridge using of_drm_find_and_get_bridge().
> 
> Also keep the "connected to non-panel bridge (unsupported)\n" error logic
> by using the drm_bridge_is_panel() function.
> 
> Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
> ---
>  drivers/gpu/drm/mcde/Kconfig    |  1 -
>  drivers/gpu/drm/mcde/mcde_dsi.c | 41 +++++++++--------------------------------
>  2 files changed, 9 insertions(+), 33 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mcde/Kconfig b/drivers/gpu/drm/mcde/Kconfig
> index 6ebfb930cbfa..81e7d3796c06 100644
> --- a/drivers/gpu/drm/mcde/Kconfig
> +++ b/drivers/gpu/drm/mcde/Kconfig
> @@ -10,7 +10,6 @@ config DRM_MCDE
>  	select DRM_MIPI_DSI
>  	select DRM_BRIDGE
>  	select DRM_PANEL
> -	select DRM_PANEL_BRIDGE
>  	select DRM_KMS_HELPER
>  	select DRM_GEM_DMA_HELPER
>  	help
> diff --git a/drivers/gpu/drm/mcde/mcde_dsi.c b/drivers/gpu/drm/mcde/mcde_dsi.c
> index 77cf253a2152..daac8d67913d 100644
> --- a/drivers/gpu/drm/mcde/mcde_dsi.c
> +++ b/drivers/gpu/drm/mcde/mcde_dsi.c
> @@ -37,7 +37,6 @@ struct mcde_dsi {
>  	struct device *dev;
>  	struct mcde *mcde;
>  	struct drm_bridge bridge;
> -	struct drm_panel *panel;
>  	struct mipi_dsi_host dsi_host;
>  	struct mipi_dsi_device *mdsi;
>  	const struct drm_display_mode *mode;
> @@ -1074,7 +1073,6 @@ static int mcde_dsi_bind(struct device *dev, struct device *master,
>  	struct drm_device *drm = data;
>  	struct mcde *mcde = to_mcde(drm);
>  	struct mcde_dsi *d = dev_get_drvdata(dev);
> -	struct drm_panel *panel = NULL;
>  	struct drm_bridge *bridge __free(drm_bridge_put) = NULL;
>  
>  	if (!of_get_available_child_count(dev->of_node)) {
> @@ -1102,40 +1100,21 @@ static int mcde_dsi_bind(struct device *dev, struct device *master,
>  
>  	/* Look for a panel as a child to this node */
>  	for_each_available_child_of_node_scoped(dev->of_node, child) {
> -		panel = of_drm_find_panel(child);
> -		if (IS_ERR(panel)) {
> -			dev_err(dev, "failed to find panel try bridge (%ld)\n",
> -				PTR_ERR(panel));
> -			panel = NULL;
> -
> -			bridge = of_drm_find_and_get_bridge(child);
> -			if (!bridge) {
> -				dev_err(dev, "failed to find bridge\n");
> -				return -EINVAL;
> -			}
> +		bridge = of_drm_find_and_get_bridge(child);
> +		if (!bridge) {
> +			dev_err(dev, "failed to find bridge\n");
> +			return -EINVAL;
>  		}
>  
> -		if (panel || bridge)
> -			break;
> +		break;
>  	}
> -	if (panel) {
> -		bridge = drm_panel_bridge_add_typed(panel,
> -						    DRM_MODE_CONNECTOR_DSI);
> -		drm_panel_put(panel);
> -		if (IS_ERR(bridge)) {
> -			dev_err(dev, "error adding panel bridge\n");
> -			return PTR_ERR(bridge);
> -		}
> -		drm_bridge_get(bridge);
> -		dev_info(dev, "connected to panel\n");
> -		d->panel = panel;
> -	} else if (bridge) {
> +	if (!bridge) {
> +		dev_err(dev, "no bridge\n");
> +		return -ENODEV;
> +	} else if (!drm_bridge_is_panel(bridge)) {
>  		/* TODO: AV8100 HDMI encoder goes here for example */
>  		dev_info(dev, "connected to non-panel bridge (unsupported)\n");
>  		return -ENODEV;

I wonder if we still need that branch. Every panel is a bridge now, and
it looks like we don't have any specific panel handling in this driver,
so I guess it supports bridges already?

Linus, do you know why this condition was here in the first place?

Maxime

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