Re: [PATCH v2 2/7] drm: verisilicon: stop using deprecated devm_drm_of_get_bridge()

[Icenowy Zheng]

在 2026-09-29二的 15:39 +0200，Luca Ceresoli写道：
> devm_drm_of_get_bridge() is deprecated, switch to
> of_drm_get_bridge_by_endpoint(). As of_drm_get_bridge_by_endpoint()
> returns
> a refcounted bridge, ensure it is put by using bridge.next_bridge.
> 
> Fixes build failure when CONFIG_OF is disabled.
> 
> Fixes: aa8a8c7e4641 ("drm/bridge: panel: move all code to
> drm_panel.c")
> Reported-by: Arnd Bergmann <arnd@xxxxxxxxxx>
> Closes:
> https://lore.kernel.org/r/20260928161605.2271412-1-arnd@xxxxxxxxxx
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> Closes:
> https://lore.kernel.org/oe-kbuild-all/202609291109.OIsGTysr-lkp@xxxxxxxxx/
> Closes:
> https://lore.kernel.org/oe-kbuild-all/202609290408.BOs7sk55-lkp@xxxxxxxxx/
> Signed-off-by: Luca Ceresoli <luca.ceresoli@xxxxxxxxxxx>

Checked the code in drm_bridge.c, and it looks like the lifetime of
next_bridge should be indirectly managed by devm when
devm_drm_bridge_alloc() successes and the next_bridge field assigned,
so the only explicit put needed here should be in the alloc failure
path.

Patch is:

```
Reviewed-by: Icenowy Zheng <zhengxingda@xxxxxxxxxxx>
```

> 
> ---
> 
> Changes in v2:
> - fix bridge reference leak on attach error path

It should be `bridge alloc error` instead of `attach error`, but I
don't know how to correct the error in the changelog, and anyway it
won't be part of the final commit.

Thanks,
Icenowy

> - mention lkp report
> ---
>  drivers/gpu/drm/verisilicon/vs_bridge.c | 11 ++++++-----
>  drivers/gpu/drm/verisilicon/vs_bridge.h |  1 -
>  2 files changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/verisilicon/vs_bridge.c
> b/drivers/gpu/drm/verisilicon/vs_bridge.c
> index dc7c85b07fe3..3a5091c0ac2c 100644
> --- a/drivers/gpu/drm/verisilicon/vs_bridge.c
> +++ b/drivers/gpu/drm/verisilicon/vs_bridge.c
> @@ -29,7 +29,7 @@ static int vs_bridge_attach(struct drm_bridge
> *bridge,
>  {
>  	struct vs_bridge *vbridge = drm_bridge_to_vs_bridge(bridge);
>  
> -	return drm_bridge_attach(encoder, vbridge->next_bridge,
> +	return drm_bridge_attach(encoder, vbridge->base.next_bridge,
>  				 bridge, flags);
>  }
>  
> @@ -303,8 +303,7 @@ struct vs_bridge *vs_bridge_init(struct
> drm_device *drm_dev,
>  		return NULL;
>  	}
>  
> -	next = devm_drm_of_get_bridge(drm_dev->dev, drm_dev->dev-
> >of_node,
> -				      output, intf);
> +	next = of_drm_get_bridge_by_endpoint(drm_dev->dev->of_node,
> output, intf);
>  	if (IS_ERR(next)) {
>  		ret = PTR_ERR(next);
>  		if (ret != -EPROBE_DEFER)
> @@ -321,12 +320,14 @@ struct vs_bridge *vs_bridge_init(struct
> drm_device *drm_dev,
>  
>  	bridge = devm_drm_bridge_alloc(drm_dev->dev, struct
> vs_bridge, base,
>  				       bridge_funcs);
> -	if (IS_ERR(bridge))
> +	if (IS_ERR(bridge)) {
> +		drm_bridge_put(next);
>  		return ERR_PTR(PTR_ERR(bridge));
> +	}
>  
>  	bridge->crtc = crtc;
>  	bridge->intf = intf;
> -	bridge->next_bridge = next;
> +	bridge->base.next_bridge = next;
>  
>  	if (intf == VSDC_OUTPUT_INTERFACE_DPI)
>  		enctype = DRM_MODE_ENCODER_DPI;
> diff --git a/drivers/gpu/drm/verisilicon/vs_bridge.h
> b/drivers/gpu/drm/verisilicon/vs_bridge.h
> index 70fee1749699..2b0ed94e4520 100644
> --- a/drivers/gpu/drm/verisilicon/vs_bridge.h
> +++ b/drivers/gpu/drm/verisilicon/vs_bridge.h
> @@ -25,7 +25,6 @@ struct vs_bridge {
>  	struct drm_connector *conn;
>  
>  	struct vs_crtc *crtc;
> -	struct drm_bridge *next_bridge;
>  	enum vs_bridge_output_interface intf;
>  };
>