Re: [PATCH v6 06/10] drm/amd/display: Allow backlight registration to fail

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] Propagating backlight registration failures causes the entire AMDGPU driver probe to fail, completely breaking all display outputs.
--

commit 290c274dbf0e6988a8d83dadd2c54c417b03e056
Author: Mario Limonciello (AMD) <superm1@kernel.org>

drm/amd/display: Allow backlight registration to fail

This commit changes backlight registration in the AMD display manager to
return error codes instead of ignoring them. This allows upstream callers
to detect when backlight initialization fails.

> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> index 9b3e2fc6cef5d..2f87940aaea42 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

[ ... ]

> @@ -8225,7 +8230,9 @@ amdgpu_dm_connector_late_register(struct drm_connector *connector)
>  			return r;
>  	}
>  
> -	amdgpu_dm_register_backlight_device(amdgpu_dm_connector);
> +	r = amdgpu_dm_register_backlight_device(amdgpu_dm_connector);
> +	if (r)
> +		return r;

[Severity: High]
Will returning this error abort the entire GPU probe?

If backlight_device_register() fails in amdgpu_dm_register_backlight_device()
(for instance, due to a sysfs name collision, memory allocation failure, or
ACPI issue), propagating this error here causes drm_connector_register() and
ultimately drm_dev_register() to fail.

Because generic framebuffers like efifb or simpledrm are explicitly removed
by aperture_remove_conflicting_pci_devices() before drm_dev_register() is
called, does failing the PCI probe at this stage leave the system with a
dead screen and no display driver at all?

Should a non-critical backlight initialization failure be treated as fatal to
the entire display adapter?

>  
>  	if ((connector->connector_type == DRM_MODE_CONNECTOR_DisplayPort) ||
>  	    (connector->connector_type == DRM_MODE_CONNECTOR_eDP)) {

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260624165751.2014759-1-mario.limonciello@amd.com?part=6