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

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Hi Javier

Am 03.09.24 um 12:18 schrieb Javier Martinez Canillas:
Thomas Zimmermann <tzimmermann@xxxxxxx> 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@xxxxxxx>
---
  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 ?

I did a

  git grep -B4 drm_fb_helper_unregister_info

on drm-tip and all callers, such as [1], test fb_helper->info before calling the function. So it's safe to remove the test.

[1] https://elixir.bootlin.com/linux/v6.10/source/drivers/gpu/drm/drm_fbdev_dma.c#L162


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

Ok.


Other than that, the patch looks good to me:

Reviewed-by: Javier Martinez Canillas <javierm@xxxxxxxxxx>

Thanks.

Best regards
Thomas



--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)




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