[PATCH v2] drm/gem: Check for valid formats

[Thomas Zimmermann]

Am 03.01.23 um 14:59 schrieb Maíra Canal:
> Currently, drm_gem_fb_create() doesn't check if the pixel format is
> supported, which can lead to the acceptance of invalid pixel formats
> e.g. the acceptance of invalid modifiers. Therefore, add a check for
> valid formats on drm_gem_fb_create().
> 
> Moreover, note that this check is only valid for atomic drivers,
> because, for non-atomic drivers, checking drm_any_plane_has_format() is
> not possible since the format list for the primary plane is fake, and
> we'd therefor reject valid formats.
> 
> Suggested-by: Thomas Zimmermann <tzimmermann at suse.de>
> Signed-off-by: Maíra Canal <mcanal at igalia.com>

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

> ---
> 
> v1 -> v2: https://lore.kernel.org/dri-devel/20230103125322.855089-1-mcanal@igalia.com/T/
> - Check the modifier for each pixel plane in multi-plane formats (Thomas Zimmermann).
> - Use drm_dbg_kms() instead of drm_dbg() (Thomas Zimmermann).
> 
> ---
>   Documentation/gpu/todo.rst                   |  7 ++-----
>   drivers/gpu/drm/drm_gem_framebuffer_helper.c | 13 +++++++++++++
>   2 files changed, 15 insertions(+), 5 deletions(-)
> 
> diff --git a/Documentation/gpu/todo.rst b/Documentation/gpu/todo.rst
> index 1f8a5ebe188e..68bdafa0284f 100644
> --- a/Documentation/gpu/todo.rst
> +++ b/Documentation/gpu/todo.rst
> @@ -276,11 +276,8 @@ Various hold-ups:
>   - Need to switch to drm_fbdev_generic_setup(), otherwise a lot of the custom fb
>     setup code can't be deleted.
> 
> -- Many drivers wrap drm_gem_fb_create() only to check for valid formats. For
> -  atomic drivers we could check for valid formats by calling
> -  drm_plane_check_pixel_format() against all planes, and pass if any plane
> -  supports the format. For non-atomic that's not possible since like the format
> -  list for the primary plane is fake and we'd therefor reject valid formats.
> +- Need to switch to drm_gem_fb_create(), as now drm_gem_fb_create() checks for
> +  valid formats for atomic drivers.
> 
>   - Many drivers subclass drm_framebuffer, we'd need a embedding compatible
>     version of the varios drm_gem_fb_create functions. Maybe called
> diff --git a/drivers/gpu/drm/drm_gem_framebuffer_helper.c b/drivers/gpu/drm/drm_gem_framebuffer_helper.c
> index e93533b86037..92d748f8553f 100644
> --- a/drivers/gpu/drm/drm_gem_framebuffer_helper.c
> +++ b/drivers/gpu/drm/drm_gem_framebuffer_helper.c
> @@ -9,6 +9,7 @@
>   #include <linux/module.h>
> 
>   #include <drm/drm_damage_helper.h>
> +#include <drm/drm_drv.h>
>   #include <drm/drm_fourcc.h>
>   #include <drm/drm_framebuffer.h>
>   #include <drm/drm_gem.h>
> @@ -164,6 +165,18 @@ int drm_gem_fb_init_with_funcs(struct drm_device *dev,
> 		return -EINVAL;
> 	}
> 
> +	if (drm_drv_uses_atomic_modeset(dev)) {
> +		for (i = 0; i < info->num_planes; i++) {
> +			if (!drm_any_plane_has_format(dev, mode_cmd->pixel_format,
> +						      mode_cmd->modifier[i])) {
> +				drm_dbg_kms(dev,
> +					    "Unsupported pixel format %p4cc / modifier 0x%llx\n",
> +					    &mode_cmd->pixel_format, mode_cmd->modifier[i]);
> +				return -EINVAL;
> +			}
> +		}
> +	}
> +
> 	for (i = 0; i < info->num_planes; i++) {
> 		unsigned int width = mode_cmd->width / (i ? info->hsub : 1);
> 		unsigned int height = mode_cmd->height / (i ? info->vsub : 1);
> --
> 2.38.1
> 

-- 
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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