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

[Thomas Zimmermann <tzimmermann@suse.de>]

Hi

Am 12.11.25 um 13:53 schrieb 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@oss.qualcomm.com>
>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
>> Fixes: b1d0e470f881 ("drm/imx/ipuv3: Compute dumb-buffer sizes with drm_mode_size_dumb()")
>> Cc: Thomas Zimmermann <tzimmermann@suse.de>
>> Cc: Philipp Zabel <p.zabel@pengutronix.de>
>> Cc: Shawn Guo <shawnguo@kernel.org>
>> Cc: Sascha Hauer <s.hauer@pengutronix.de>
>> Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
>> Cc: Fabio Estevam <festevam@gmail.com>
>> Cc: dri-devel@lists.freedesktop.org
>> Cc: imx@lists.linux.dev
>> Cc: linux-arm-kernel@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@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@pengutronix.de>

Thanks a lot. I'll land this fix ASAP.

Best regards
Thomas

>
> regards
> Philipp

-- 
--
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)