Nouveau - Sep 2024 - [PATCH v3 02/81] drm/fbdev-helper: Set and clear VGA switcheroo client from fb_info

Call vga_switcheroo_client_fb_set() with the PCI device from the
instance of struct fb_info. All fbdev clients now run these calls.
For non-PCI devices or drivers without vga-switcheroo, this does
nothing. For i915 and radeon, it allows these drivers to use a
common fbdev client.

The device is the same as the one stored in struct drm_client and
struct drm_fb_helper, so there is no difference in behavior. Some
NULL-pointer checks are being removed, where those pointers cannot
be NULL.

Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
---
 drivers/gpu/drm/drm_fb_helper.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index af1fe79c701d..13095d38aa42 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -562,8 +562,12 @@ EXPORT_SYMBOL(drm_fb_helper_release_info);
  */
 void drm_fb_helper_unregister_info(struct drm_fb_helper *fb_helper)
 {
-	if (fb_helper && fb_helper->info)
-		unregister_framebuffer(fb_helper->info);
+	struct fb_info *info = fb_helper->info;
+	struct device *dev = info->device;
+
+	if (dev_is_pci(dev))
+		vga_switcheroo_client_fb_set(to_pci_dev(dev), NULL);
+	unregister_framebuffer(fb_helper->info);
 }
 EXPORT_SYMBOL(drm_fb_helper_unregister_info);
 
@@ -1615,6 +1619,7 @@ static int drm_fb_helper_single_fb_probe(struct
drm_fb_helper *fb_helper)
 	struct drm_client_dev *client = &fb_helper->client;
 	struct drm_device *dev = fb_helper->dev;
 	struct drm_fb_helper_surface_size sizes;
+	struct fb_info *info;
 	int ret;
 
 	ret = drm_fb_helper_find_sizes(fb_helper, &sizes);
@@ -1632,9 +1637,11 @@ static int drm_fb_helper_single_fb_probe(struct
drm_fb_helper *fb_helper)
 
 	strcpy(fb_helper->fb->comm, "[fbcon]");
 
+	info = fb_helper->info;
+
 	/* Set the fb info for vgaswitcheroo clients. Does nothing otherwise. */
-	if (dev_is_pci(dev->dev))
-		vga_switcheroo_client_fb_set(to_pci_dev(dev->dev), fb_helper->info);
+	if (dev_is_pci(info->device))
+		vga_switcheroo_client_fb_set(to_pci_dev(info->device), info);
 
 	return 0;
 }
-- 
2.46.0

Thomas Zimmermann <tzimmermann at suse.de> writes:

Hello Thomas,
> Call vga_switcheroo_client_fb_set() with the PCI device from the
> instance of struct fb_info. All fbdev clients now run these calls.
> For non-PCI devices or drivers without vga-switcheroo, this does
> nothing. For i915 and radeon, it allows these drivers to use a
> common fbdev client.
>
> The device is the same as the one stored in struct drm_client and
> struct drm_fb_helper, so there is no difference in behavior. Some
> NULL-pointer checks are being removed, where those pointers cannot
> be NULL.
>
> Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
> ---
>  drivers/gpu/drm/drm_fb_helper.c | 15 +++++++++++----
>  1 file changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_fb_helper.c
b/drivers/gpu/drm/drm_fb_helper.c
> index af1fe79c701d..13095d38aa42 100644
> --- a/drivers/gpu/drm/drm_fb_helper.c
> +++ b/drivers/gpu/drm/drm_fb_helper.c
> @@ -562,8 +562,12 @@ EXPORT_SYMBOL(drm_fb_helper_release_info);
>   */
>  void drm_fb_helper_unregister_info(struct drm_fb_helper *fb_helper)
>  {
> -	if (fb_helper && fb_helper->info)
> -		unregister_framebuffer(fb_helper->info);
I'm not sure if we can assume these won't be NULL... AFAICT some drivers
still have their own struct drm_client_funcs vtable and could potentially
pass a NULL struct drm_fb_helper ?

If you think that's safe to do this and the function semantics should be
changed, then I think that the kernel-doc needs to be updated:

- * @fb_helper: driver-allocated fbdev helper, can be NULL
+ * @fb_helper: driver-allocated fbdev helper, must not be NULL

Other than that, the patch looks good to me:

Reviewed-by: Javier Martinez Canillas <javierm at redhat.com>

-- 
Best regards,

Javier Martinez Canillas
Core Platforms
Red Hat