[PATCH v2] drm/bridge: synopsys: dw-dp: return when attach bridge fail

[PATCH v2] drm/bridge: synopsys: dw-dp: return when attach bridge fail

[Osama Abdelkader]

When drm_bridge_attach() fails, the function should return an error
instead of continuing execution.

Fixes: 86eecc3a9c2e ("drm/bridge: synopsys: Add DW DPTX Controller support library")
Cc: stable@vger.kernel.org

Signed-off-by: Osama Abdelkader <osama.abdelkader@gmail.com>
---
v2:
use concise error message
add Fixes and Cc tags
---
 drivers/gpu/drm/bridge/synopsys/dw-dp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-dp.c b/drivers/gpu/drm/bridge/synopsys/dw-dp.c
index 82aaf74e1bc0..bc311a596dff 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-dp.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-dp.c
@@ -2063,7 +2063,7 @@ struct dw_dp *dw_dp_bind(struct device *dev, struct drm_encoder *encoder,
 
 	ret = drm_bridge_attach(encoder, bridge, NULL, DRM_BRIDGE_ATTACH_NO_CONNECTOR);
 	if (ret)
-		dev_err_probe(dev, ret, "Failed to attach bridge\n");
+		return ERR_PTR(dev_err_probe(dev, ret, "Failed to attach bridge\n"));
 
 	dw_dp_init_hw(dp);
 
-- 
2.43.0

Re: [PATCH v2] drm/bridge: synopsys: dw-dp: return when attach bridge fail

[Luca Ceresoli]

Hello Osama, Andy Yan,

Andy, a question for you below.

On Wed Dec 31, 2025 at 3:41 PM CET, Osama Abdelkader wrote:
> When drm_bridge_attach() fails, the function should return an error
> instead of continuing execution.
>
> Fixes: 86eecc3a9c2e ("drm/bridge: synopsys: Add DW DPTX Controller support library")
> Cc: stable@vger.kernel.org
>
> Signed-off-by: Osama Abdelkader <osama.abdelkader@gmail.com>
> ---
> v2:
> use concise error message
> add Fixes and Cc tags
> ---
>  drivers/gpu/drm/bridge/synopsys/dw-dp.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-dp.c b/drivers/gpu/drm/bridge/synopsys/dw-dp.c
> index 82aaf74e1bc0..bc311a596dff 100644
> --- a/drivers/gpu/drm/bridge/synopsys/dw-dp.c
> +++ b/drivers/gpu/drm/bridge/synopsys/dw-dp.c
> @@ -2063,7 +2063,7 @@ struct dw_dp *dw_dp_bind(struct device *dev, struct drm_encoder *encoder,
>
>  	ret = drm_bridge_attach(encoder, bridge, NULL, DRM_BRIDGE_ATTACH_NO_CONNECTOR);
>  	if (ret)
> -		dev_err_probe(dev, ret, "Failed to attach bridge\n");
> +		return ERR_PTR(dev_err_probe(dev, ret, "Failed to attach bridge\n"));

Your change looks good now. However there is aanother issue, sorry for not
having noticed before.

While reading the dw_dp_bind() code in its entirety I have noticed that on
any error after drm_bridge_attach() (and also a drm_bridge_attach() error,
with this patch) it returns without undoing the previous actions. This is
fine for devm actions, but a problem for non-devm actions, which start at
drm_dp_aux_register().

For example, if phy_init() fails, dw_dp_bind() returns without calling
drm_dp_aux_unregister(), thus leaking the resources previously allocated by
drm_dp_aux_register().

Andy, can you tell whether my analysis is correct?

If it is, this should be fixed before applying this patch. Osama, do you
think you can add such a patch in your next iteration?

Best regards,
Luca

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

Re: [PATCH v2] drm/bridge: synopsys: dw-dp: return when attach bridge fail

[Osama Abdelkader]

On Fri, Jan 02, 2026 at 11:46:08AM +0100, Luca Ceresoli wrote:
> Hello Osama, Andy Yan,
> 
> Andy, a question for you below.
> 
> On Wed Dec 31, 2025 at 3:41 PM CET, Osama Abdelkader wrote:
> > When drm_bridge_attach() fails, the function should return an error
> > instead of continuing execution.
> >
> > Fixes: 86eecc3a9c2e ("drm/bridge: synopsys: Add DW DPTX Controller support library")
> > Cc: stable@vger.kernel.org
> >
> > Signed-off-by: Osama Abdelkader <osama.abdelkader@gmail.com>
> > ---
> > v2:
> > use concise error message
> > add Fixes and Cc tags
> > ---
> >  drivers/gpu/drm/bridge/synopsys/dw-dp.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/bridge/synopsys/dw-dp.c b/drivers/gpu/drm/bridge/synopsys/dw-dp.c
> > index 82aaf74e1bc0..bc311a596dff 100644
> > --- a/drivers/gpu/drm/bridge/synopsys/dw-dp.c
> > +++ b/drivers/gpu/drm/bridge/synopsys/dw-dp.c
> > @@ -2063,7 +2063,7 @@ struct dw_dp *dw_dp_bind(struct device *dev, struct drm_encoder *encoder,
> >
> >  	ret = drm_bridge_attach(encoder, bridge, NULL, DRM_BRIDGE_ATTACH_NO_CONNECTOR);
> >  	if (ret)
> > -		dev_err_probe(dev, ret, "Failed to attach bridge\n");
> > +		return ERR_PTR(dev_err_probe(dev, ret, "Failed to attach bridge\n"));
> 
> Your change looks good now. However there is aanother issue, sorry for not
> having noticed before.
> 
> While reading the dw_dp_bind() code in its entirety I have noticed that on
> any error after drm_bridge_attach() (and also a drm_bridge_attach() error,
> with this patch) it returns without undoing the previous actions. This is
> fine for devm actions, but a problem for non-devm actions, which start at
> drm_dp_aux_register().
> 
> For example, if phy_init() fails, dw_dp_bind() returns without calling
> drm_dp_aux_unregister(), thus leaking the resources previously allocated by
> drm_dp_aux_register().
> 
> Andy, can you tell whether my analysis is correct?
> 
> If it is, this should be fixed before applying this patch. Osama, do you
> think you can add such a patch in your next iteration?

Thanks Luca for the review, I just sent v3.

Best regards,
Osama

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