drm/imx/ipuv3: Fix dumb-buffer allocation for non-RGB formats

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: b1d0e47 ("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
Tested-by: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Link: https://patch.msgid.link/20251104153832.189666-1-tzimmermann@suse.de

Author: tdz

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);