[PATCH 2/3] drm/gem-shmem: revert the 8-byte alignment constraint

Ludovic Desroches posted 3 patches 2 months, 2 weeks ago
[PATCH 2/3] drm/gem-shmem: revert the 8-byte alignment constraint
Posted by Ludovic Desroches 2 months, 2 weeks ago
Using drm_mode_size_dumb() to compute the size of dumb buffers introduced
an 8-byte alignment constraint on the pitch that wasn’t present before.
Let’s remove this constraint, which isn’t necessarily required and may
cause buffers to be allocated larger than needed.

Signed-off-by: Ludovic Desroches <ludovic.desroches@microchip.com>
---
 drivers/gpu/drm/drm_gem_shmem_helper.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
index dc94a27710e5f48839a5d2e9e9ea5152ff22e438..93b9cff89080f94e5d6e4663ef642b4c36e93c71 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -559,7 +559,7 @@ int drm_gem_shmem_dumb_create(struct drm_file *file, struct drm_device *dev,
 {
 	int ret;
 
-	ret = drm_mode_size_dumb(dev, args, SZ_8, 0);
+	ret = drm_mode_size_dumb(dev, args, 0, 0);
 	if (ret)
 		return ret;
 

-- 
2.51.0

Re: [PATCH 2/3] drm/gem-shmem: revert the 8-byte alignment constraint
Posted by Thomas Zimmermann 2 months, 1 week ago

Am 26.11.25 um 15:44 schrieb Ludovic Desroches:
> Using drm_mode_size_dumb() to compute the size of dumb buffers introduced
> an 8-byte alignment constraint on the pitch that wasn’t present before.
> Let’s remove this constraint, which isn’t necessarily required and may
> cause buffers to be allocated larger than needed.
>
> Signed-off-by: Ludovic Desroches <ludovic.desroches@microchip.com>

Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>

Fixes: 4977dcecb931 ("drm/gem-shmem: Compute dumb-buffer sizes with 
drm_mode_size_dumb()")


> ---
>   drivers/gpu/drm/drm_gem_shmem_helper.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
> index dc94a27710e5f48839a5d2e9e9ea5152ff22e438..93b9cff89080f94e5d6e4663ef642b4c36e93c71 100644
> --- a/drivers/gpu/drm/drm_gem_shmem_helper.c
> +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
> @@ -559,7 +559,7 @@ int drm_gem_shmem_dumb_create(struct drm_file *file, struct drm_device *dev,
>   {
>   	int ret;
>   
> -	ret = drm_mode_size_dumb(dev, args, SZ_8, 0);
> +	ret = drm_mode_size_dumb(dev, args, 0, 0);
>   	if (ret)
>   		return ret;
>   
>

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG Nürnberg)