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 <[e-mail]>
Signed-off-by: Thomas Zimmermann <[e-mail]>
Fixes: b1d0e470f881 ("drm/imx/ipuv3: Compute dumb-buffer sizes with drm_mode_size_dumb()")
Cc: Thomas Zimmermann <[e-mail]>
Cc: Philipp Zabel <[e-mail]>
Cc: Shawn Guo <[e-mail]>
Cc: Sascha Hauer <[e-mail]>
Cc: Pengutronix Kernel Team <[e-mail]>
Cc: Fabio Estevam <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Tested-by: Philipp Zabel <[e-mail]>
Reviewed-by: Philipp Zabel <[e-mail]>
Link: https://patch.msgid.link/[e-mail]

drivers/gpu/drm/imx/ipuv3/imx-drm-core.c

···
 			       struct drm_mode_create_dumb *args)
 {
 	u32 fourcc;
-	const struct drm_format_info *info;
 	u64 pitch_align;
 	int ret;
 
···
 	 * 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);