[Lima] [PATCH] drm: Return error codes from struct drm_driver.gem_create_object

[Thomas Zimmermann]

Hi

Am 06.12.21 um 11:42 schrieb Dan Carpenter:
> On Tue, Nov 30, 2021 at 10:52:55AM +0100, Thomas Zimmermann wrote:
>> GEM helper libraries use struct drm_driver.gem_create_object to let
>> drivers override GEM object allocation. On failure, the call returns
>> NULL.
>>
>> Change the semantics to make the calls return a pointer-encoded error.
>> This aligns the callback with its callers. Fixes the ingenic driver,
>> which already returns an error pointer.
>>
>> Also update the callers to handle the involved types more strictly.
>>
>> Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
>> ---
>> There is an alternative patch at [1] that updates the value returned
>> by ingenics' gem_create_object to NULL. Fixing the interface to return
>> an errno code is more consistent with the rest of the GEM functions.
>>
>> [1] https://lore.kernel.org/dri-devel/20211118111522.GD1147@kili/
> 
> My fix was already applied and backported to -stable etc...  Your
> patch is not developed against a current tree so you broke it.

Do you have a specific link? I just checked the stable tree at [1] and 
there no trace of your patch.

Patches for DRM should go through through DRM trees; drm-misc-fixes in 
this case. Exceptions should at least be announce on dri-devel. Neither 
is the case here.

Best regards
Thomas

[1] 
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/drivers/gpu/drm/ingenic/ingenic-drm-drv.c

> 
> That's the tricky thing with changing the API because say people wrote
> their code last week where returning NULL was correct.  When they submit
> their driver upstream, everything will merge and build but it will break
> at runtime.
> 
> For now, it's only vc4_create_object() which is broken.
> 
> regards,
> dan carpenter
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev
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