[PATCH v2] drm/imx/ipuv3: Fix dumb-buffer allocation for non-RGB formats

[Philipp Zabel]

On Di, 2025-11-04 at 16:38 +0100, Thomas Zimmermann wrote:
> Align pitch to multiples of 8 pixels for bpp values that do not map
> to RGB formats. The call to drm_driver_color_mode_format() fails with
> DRM_INVALID_FORMAT in these cases. Fall back to manually computing
> the pitch alignment from which drm_mode_size_dumb() can compute the
> correct pitch.
> 
> Fixes userspace that allocates dumb buffers for YUV formats, where
> bpp equals 12. A common example is the IGT kms_getfb test.
>
> v2:
> - ignore width in calculation
> 
> Suggested-by: Dmitry Baryshkov <dmitry.baryshkov at oss.qualcomm.com>
> Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
> Fixes: b1d0e470f881 ("drm/imx/ipuv3: Compute dumb-buffer sizes with drm_mode_size_dumb()")
> Cc: Thomas Zimmermann <tzimmermann at suse.de>
> Cc: Philipp Zabel <p.zabel at pengutronix.de>
> Cc: Shawn Guo <shawnguo at kernel.org>
> Cc: Sascha Hauer <s.hauer at pengutronix.de>
> Cc: Pengutronix Kernel Team <kernel at pengutronix.de>
> Cc: Fabio Estevam <festevam at gmail.com>
> Cc: dri-devel at lists.freedesktop.org
> Cc: imx at lists.linux.dev
> Cc: linux-arm-kernel at lists.infradead.org
> ---
> This patch is based on Dmitry's fix for msm. [1] Please test.

Thank you,

[IGT] kms_getfb: finished subtest getfb2-accept-nv12, CRASH -> SUCCESS

Tested-by: Philipp Zabel <p.zabel at pengutronix.de>

> There could later be a helper to contain these aligmentment calculations
> in a single place.
> 
> [1] https://lore.kernel.org/dri-devel/20251103-drm-msm-fix-nv12-v2-1-75103b64576e@oss.qualcomm.com/
> ---
>  drivers/gpu/drm/imx/ipuv3/imx-drm-core.c | 16 +++++++++-------
>  1 file changed, 9 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c b/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c
> index 465b5a6ad5bb..eddb471119c6 100644
> --- a/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c
> +++ b/drivers/gpu/drm/imx/ipuv3/imx-drm-core.c
> @@ -144,7 +144,6 @@ static int imx_drm_dumb_create(struct drm_file *file_priv,
>  			       struct drm_mode_create_dumb *args)
>  {
>  	u32 fourcc;
> -	const struct drm_format_info *info;
>  	u64 pitch_align;
>  	int ret;
>  
> @@ -156,12 +155,15 @@ static int imx_drm_dumb_create(struct drm_file *file_priv,
>  	 * the allocated buffer.
>  	 */
>  	fourcc = drm_driver_color_mode_format(drm, args->bpp);
> -	if (fourcc == DRM_FORMAT_INVALID)
> -		return -EINVAL;
> -	info = drm_format_info(fourcc);
> -	if (!info)
> -		return -EINVAL;
> -	pitch_align = drm_format_info_min_pitch(info, 0, SZ_8);
> +	if (fourcc != DRM_FORMAT_INVALID) {
> +		const struct drm_format_info *info = drm_format_info(fourcc);
> +
> +		if (!info)
> +			return -EINVAL;
> +		pitch_align = drm_format_info_min_pitch(info, 0, 8);
> +	} else {
> +		pitch_align = DIV_ROUND_UP(args->bpp, SZ_8) * 8;
> +	}
>  	if (!pitch_align || pitch_align > U32_MAX)
>  		return -EINVAL;
>  	ret = drm_mode_size_dumb(drm, args, pitch_align, 0);

Reviewed-by: Philipp Zabel <p.zabel at pengutronix.de>

regards
Philipp