Re: [PATCH v2 5/7] drm: Implement struct vga_switcheroo_client_ops.pre_switch

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] `vga_switcheroo_client_fb_set()` and the `fb_info` field in `struct vga_switcheroo_client` are orphaned and remain as dead code.
--

--- Patch [5]: [PATCH v2 5/7] drm: Implement struct vga_switcheroo_client_ops.pre_switch ---
commit d5ba75db20f40c6dde86b90da7c25acad6f23b57
Author: Thomas Zimmermann <tzimmermann@suse.de>

drm: Implement struct vga_switcheroo_client_ops.pre_switch

This commit implements the pre_switch callback for vga_switcheroo in amdgpu,
i915, nouveau, and radeon drivers. It pushes fbcon updates from vga_switcheroo
into DRM's fbdev emulation and removes calls to vga_switcheroo_client_fb_set()
from fbcon to prevent deadlocks.

> diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
> index 9f5c4c101581d..974c7dcf52514 100644
> --- a/drivers/video/fbdev/core/fbcon.c
> +++ b/drivers/video/fbdev/core/fbcon.c
[ ... ]
> @@ -2987,10 +2983,6 @@ static int do_fb_registered(struct fb_info *info)
>  		}
>  	}
>  
> -	/* Set the fb info for vga_switcheroo clients. Does nothing otherwise. */
> -	if (info->device && dev_is_pci(info->device))
> -		vga_switcheroo_client_fb_set(to_pci_dev(info->device), info);
> -

[Severity: Low]
With the removal of these calls from fbcon, are there any remaining users of
vga_switcheroo_client_fb_set()?

It looks like the exported function in drivers/gpu/vga/vga_switcheroo.c is
now completely unused:

void vga_switcheroo_client_fb_set(struct pci_dev *pdev,
				 struct fb_info *info)
{
	struct vga_switcheroo_client *client;

	mutex_lock(&vgasr_mutex);
	client = find_client_from_pci(&vgasr_priv.clients, pdev);
	if (client)
		client->fb_info = info;
	mutex_unlock(&vgasr_mutex);
}
EXPORT_SYMBOL(vga_switcheroo_client_fb_set);

Because client->fb_info is never populated, does this also leave dead code
in vga_switchto_stage2() where it checks for the fallback?

#if defined(CONFIG_FB)
	else if (new_client->fb_info)
		fb_switch_outputs(new_client->fb_info);
#endif

Would it make sense to remove the orphaned vga_switcheroo_client_fb_set()
function, the fb_info field in struct vga_switcheroo_client, and the
unreachable fallback block to complete the cleanup?

>  	return ret;
>  }

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260709092215.168172-1-tzimmermann@suse.de?part=5