[v2] drm/bridge: synopsys: dw-dp: Check return value of devm_drm_bridge_add() in dw_dp_bind()

[PATCH v2] drm/bridge: synopsys: dw-dp: Check return value of devm_drm_bridge_add() in dw_dp_bind()

Posted by Chen Ni 3 days, 23 hours ago

Return the value of devm_drm_bridge_add() in order to propagate the
error properly, if it fails due to resource allocation failure or bridge
registration failure.

This ensures that the bind function fails safely rather than proceeding
with a potentially incomplete bridge setup.

Fixes: b726970486d8 ("drm/bridge: synopsys: dw-dp: add bridge before attaching")
Signed-off-by: Chen Ni <nichen@iscas.ac.cn>
---
Changes in v2:
- Use ERR_PTR() instead of dev_err_ptr_probe().
---
 drivers/gpu/drm/bridge/synopsys/dw-dp.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-dp.c b/drivers/gpu/drm/bridge/synopsys/dw-dp.c
index 432342452484..29fcba7a47d3 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-dp.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-dp.c
@@ -2049,7 +2049,11 @@ struct dw_dp *dw_dp_bind(struct device *dev, struct drm_encoder *encoder,
 	bridge->type = DRM_MODE_CONNECTOR_DisplayPort;
 	bridge->ycbcr_420_allowed = true;
 
-	devm_drm_bridge_add(dev, bridge);
+	ret = devm_drm_bridge_add(dev, bridge);
+	if (ret) {
+		dev_err_probe(dev, ret, "failed to add bridge\n");
+		return ERR_PTR(ret);
+	}
 
 	dp->aux.dev = dev;
 	dp->aux.drm_dev = encoder->dev;
-- 
2.25.1

Re: [PATCH v2] drm/bridge: synopsys: dw-dp: Check return value of devm_drm_bridge_add() in dw_dp_bind()

Posted by Luca Ceresoli 3 days ago

On Wed Feb 4, 2026 at 10:21 AM CET, Chen Ni wrote:
> Return the value of devm_drm_bridge_add() in order to propagate the
> error properly, if it fails due to resource allocation failure or bridge
> registration failure.
>
> This ensures that the bind function fails safely rather than proceeding
> with a potentially incomplete bridge setup.
>
> Fixes: b726970486d8 ("drm/bridge: synopsys: dw-dp: add bridge before attaching")
> Signed-off-by: Chen Ni <nichen@iscas.ac.cn>

Ah, good catch, thanks for the patch!

> ---
> Changes in v2:
> - Use ERR_PTR() instead of dev_err_ptr_probe().
> ---
>  drivers/gpu/drm/bridge/synopsys/dw-dp.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-dp.c b/drivers/gpu/drm/bridge/synopsys/dw-dp.c
> index 432342452484..29fcba7a47d3 100644
> --- a/drivers/gpu/drm/bridge/synopsys/dw-dp.c
> +++ b/drivers/gpu/drm/bridge/synopsys/dw-dp.c
> @@ -2049,7 +2049,11 @@ struct dw_dp *dw_dp_bind(struct device *dev, struct drm_encoder *encoder,
>  	bridge->type = DRM_MODE_CONNECTOR_DisplayPort;
>  	bridge->ycbcr_420_allowed = true;
>
> -	devm_drm_bridge_add(dev, bridge);
> +	ret = devm_drm_bridge_add(dev, bridge);
> +	if (ret) {
> +		dev_err_probe(dev, ret, "failed to add bridge\n");
> +		return ERR_PTR(ret);
> +	}

Looks correct, but can be simpler:

	ret = devm_drm_bridge_add(dev, bridge);
	if (ret)
		return ERR_PTR(dev_err_probe(dev, ret, "failed to add bridge\n"));

Also, when sending a new iteration, it is common to _not_ send the patch as
a reply to the previous iteration. It can generate huge threads for long
series. Also I'd not be surprised if it confused some tools, even though I
just did a quick test with b4 and it seems to do the expected thing (take
v2, not v1).

Best regards,
Luca

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [PATCH v2] drm/bridge: synopsys: dw-dp: Check return value of devm_drm_bridge_add() in dw_dp_bind()

Posted by Luca Ceresoli 2 days, 23 hours ago

On Thu Feb 5, 2026 at 10:06 AM CET, Luca Ceresoli wrote:
>> --- a/drivers/gpu/drm/bridge/synopsys/dw-dp.c
>> +++ b/drivers/gpu/drm/bridge/synopsys/dw-dp.c
>> @@ -2049,7 +2049,11 @@ struct dw_dp *dw_dp_bind(struct device *dev, struct drm_encoder *encoder,
>>  	bridge->type = DRM_MODE_CONNECTOR_DisplayPort;
>>  	bridge->ycbcr_420_allowed = true;
>>
>> -	devm_drm_bridge_add(dev, bridge);
>> +	ret = devm_drm_bridge_add(dev, bridge);
>> +	if (ret) {
>> +		dev_err_probe(dev, ret, "failed to add bridge\n");
>> +		return ERR_PTR(ret);
>> +	}
>
> Looks correct, but can be simpler:
>
> 	ret = devm_drm_bridge_add(dev, bridge);
> 	if (ret)
> 		return ERR_PTR(dev_err_probe(dev, ret, "failed to add bridge\n"));

I noticed you are doing the same fix in [0] but without logging a
message. Either is fine, but I don't see why using a different policy. I
think not logging anything for devm_drm_bridge_add() is fine, because the
only error it can return is on a small memory allocation which de facto
cannot happen. So I'm OK if you just ditch the message in v3.

[0] https://lore.kernel.org/lkml/20260204090629.2209542-1-nichen@iscas.ac.cn/

Luca

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

Re:[PATCH v2] drm/bridge: synopsys: dw-dp: Check return value of devm_drm_bridge_add() in dw_dp_bind()

Posted by Andy Yan 3 days, 23 hours ago


Hello，
At 2026-02-04 17:21:48, "Chen Ni" <nichen@iscas.ac.cn> wrote:
>Return the value of devm_drm_bridge_add() in order to propagate the
>error properly, if it fails due to resource allocation failure or bridge
>registration failure.
>
>This ensures that the bind function fails safely rather than proceeding
>with a potentially incomplete bridge setup.
>
>Fixes: b726970486d8 ("drm/bridge: synopsys: dw-dp: add bridge before attaching")
>Signed-off-by: Chen Ni <nichen@iscas.ac.cn>


   Reviewed-by: Andy Yan <andyshrk@163.com>

>---
>Changes in v2:
>- Use ERR_PTR() instead of dev_err_ptr_probe().
>---
> drivers/gpu/drm/bridge/synopsys/dw-dp.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
>diff --git a/drivers/gpu/drm/bridge/synopsys/dw-dp.c b/drivers/gpu/drm/bridge/synopsys/dw-dp.c
>index 432342452484..29fcba7a47d3 100644
>--- a/drivers/gpu/drm/bridge/synopsys/dw-dp.c
>+++ b/drivers/gpu/drm/bridge/synopsys/dw-dp.c
>@@ -2049,7 +2049,11 @@ struct dw_dp *dw_dp_bind(struct device *dev, struct drm_encoder *encoder,
> 	bridge->type = DRM_MODE_CONNECTOR_DisplayPort;
> 	bridge->ycbcr_420_allowed = true;
> 
>-	devm_drm_bridge_add(dev, bridge);
>+	ret = devm_drm_bridge_add(dev, bridge);
>+	if (ret) {
>+		dev_err_probe(dev, ret, "failed to add bridge\n");
>+		return ERR_PTR(ret);
>+	}
> 
> 	dp->aux.dev = dev;
> 	dp->aux.drm_dev = encoder->dev;
>-- 
>2.25.1