drm/bridge: fsl-ldb: support downstream bridges in addition to panels

[PATCH] drm/bridge: fsl-ldb: support downstream bridges in addition to panels

Posted by Xiaolei Wang 2 months, 1 week ago

The fsl-ldb driver currently only supports connecting to a drm_panel
via of_drm_find_panel(). This prevents it from working with downstream
bridge chips such as the ITE IT6263 LVDS-to-HDMI converter.

Replace of_drm_find_panel() + devm_drm_panel_bridge_add() with
devm_drm_of_get_bridge(), which handles both panels and bridges.

This fixes the LVDS-to-HDMI display output path on i.MX8MP EVK.

Signed-off-by: Xiaolei Wang <xiaolei.wang@windriver.com>
---
 drivers/gpu/drm/bridge/fsl-ldb.c | 15 +++------------
 1 file changed, 3 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/bridge/fsl-ldb.c b/drivers/gpu/drm/bridge/fsl-ldb.c
index 5c3cf37200bc..2936c945ba52 100644
--- a/drivers/gpu/drm/bridge/fsl-ldb.c
+++ b/drivers/gpu/drm/bridge/fsl-ldb.c
@@ -292,9 +292,7 @@ static const struct drm_bridge_funcs funcs = {
 static int fsl_ldb_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
-	struct device_node *panel_node;
 	struct device_node *remote1, *remote2;
-	struct drm_panel *panel;
 	struct fsl_ldb *fsl_ldb;
 	int dual_link;
 
@@ -322,25 +320,18 @@ static int fsl_ldb_probe(struct platform_device *pdev)
 	remote2 = of_graph_get_remote_node(dev->of_node, 2, 0);
 	fsl_ldb->ch0_enabled = (remote1 != NULL);
 	fsl_ldb->ch1_enabled = (remote2 != NULL);
-	panel_node = of_node_get(remote1 ? remote1 : remote2);
 	of_node_put(remote1);
 	of_node_put(remote2);
 
-	if (!fsl_ldb->ch0_enabled && !fsl_ldb->ch1_enabled) {
-		of_node_put(panel_node);
+	if (!fsl_ldb->ch0_enabled && !fsl_ldb->ch1_enabled)
 		return dev_err_probe(dev, -ENXIO, "No panel node found");
-	}
 
 	dev_dbg(dev, "Using %s\n",
 		fsl_ldb_is_dual(fsl_ldb) ? "dual-link mode" :
 		fsl_ldb->ch0_enabled ? "channel 0" : "channel 1");
 
-	panel = of_drm_find_panel(panel_node);
-	of_node_put(panel_node);
-	if (IS_ERR(panel))
-		return PTR_ERR(panel);
-
-	fsl_ldb->panel_bridge = devm_drm_panel_bridge_add(dev, panel);
+	fsl_ldb->panel_bridge = devm_drm_of_get_bridge(dev, dev->of_node,
+						       fsl_ldb->ch0_enabled ? 1 : 2, 0);
 	if (IS_ERR(fsl_ldb->panel_bridge))
 		return PTR_ERR(fsl_ldb->panel_bridge);
 
-- 
2.43.0

Re: [PATCH] drm/bridge: fsl-ldb: support downstream bridges in addition to panels

Posted by Laurentiu Palcu 1 month, 4 weeks ago

Hi Xiaolei,

On Wed, Apr 08, 2026 at 03:28:02PM +0800, Xiaolei Wang wrote:
> The fsl-ldb driver currently only supports connecting to a drm_panel
> via of_drm_find_panel(). This prevents it from working with downstream
> bridge chips such as the ITE IT6263 LVDS-to-HDMI converter.
> 
> Replace of_drm_find_panel() + devm_drm_panel_bridge_add() with
> devm_drm_of_get_bridge(), which handles both panels and bridges.
> 
> This fixes the LVDS-to-HDMI display output path on i.MX8MP EVK.

There's already a patch sent out for this:
https://lore.kernel.org/all/20260304-dcif-upstreaming-v8-2-bec5c047edd4@oss.nxp.com/

> 
> Signed-off-by: Xiaolei Wang <xiaolei.wang@windriver.com>
> ---
>  drivers/gpu/drm/bridge/fsl-ldb.c | 15 +++------------
>  1 file changed, 3 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/fsl-ldb.c b/drivers/gpu/drm/bridge/fsl-ldb.c
> index 5c3cf37200bc..2936c945ba52 100644
> --- a/drivers/gpu/drm/bridge/fsl-ldb.c
> +++ b/drivers/gpu/drm/bridge/fsl-ldb.c
> @@ -292,9 +292,7 @@ static const struct drm_bridge_funcs funcs = {
>  static int fsl_ldb_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
> -	struct device_node *panel_node;
>  	struct device_node *remote1, *remote2;
> -	struct drm_panel *panel;
>  	struct fsl_ldb *fsl_ldb;
>  	int dual_link;
>  
> @@ -322,25 +320,18 @@ static int fsl_ldb_probe(struct platform_device *pdev)
>  	remote2 = of_graph_get_remote_node(dev->of_node, 2, 0);
>  	fsl_ldb->ch0_enabled = (remote1 != NULL);
>  	fsl_ldb->ch1_enabled = (remote2 != NULL);
> -	panel_node = of_node_get(remote1 ? remote1 : remote2);
>  	of_node_put(remote1);
>  	of_node_put(remote2);
>  
> -	if (!fsl_ldb->ch0_enabled && !fsl_ldb->ch1_enabled) {
> -		of_node_put(panel_node);
> +	if (!fsl_ldb->ch0_enabled && !fsl_ldb->ch1_enabled)
>  		return dev_err_probe(dev, -ENXIO, "No panel node found");
> -	}
>  
>  	dev_dbg(dev, "Using %s\n",
>  		fsl_ldb_is_dual(fsl_ldb) ? "dual-link mode" :
>  		fsl_ldb->ch0_enabled ? "channel 0" : "channel 1");
>  
> -	panel = of_drm_find_panel(panel_node);
> -	of_node_put(panel_node);
> -	if (IS_ERR(panel))
> -		return PTR_ERR(panel);
> -
> -	fsl_ldb->panel_bridge = devm_drm_panel_bridge_add(dev, panel);
> +	fsl_ldb->panel_bridge = devm_drm_of_get_bridge(dev, dev->of_node,
> +						       fsl_ldb->ch0_enabled ? 1 : 2, 0);
>  	if (IS_ERR(fsl_ldb->panel_bridge))
>  		return PTR_ERR(fsl_ldb->panel_bridge);
>  
> -- 
> 2.43.0
> 

-- 
Thanks,
Laurentiu