From: Tomi Valkeinen Date: Thu, 23 Apr 2026 14:21:12 +0000 (+0300) Subject: drm/fourcc: Add warning for bad bpp X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7e688812395eec7871ca4437f9bd817ee98398f0;p=thirdparty%2Fkernel%2Flinux.git drm/fourcc: Add warning for bad bpp drm_format_info_bpp() cannot be used for formats which do not have an integer bits-per-pixel in a pixel block. E.g. DRM_FORMAT_P030's plane 0 has three 10-bit pixels (Y components), and two padding bits, in a 4 byte block. That is 10.666... bits per pixel when considering the whole 4 byte block, which is what drm_format_info_bpp() does. Thus a driver that supports such formats cannot use drm_format_info_bpp(), It is a driver bug if this happens, but so handle wrong calls by printing a warning and returning 0. Reviewed-by: Laurent Pinchart Reviewed-by: Dmitry Baryshkov Acked-by: Simon Ser Link: https://patch.msgid.link/20260423-xilinx-formats-v10-1-c690c2b8ea89@ideasonboard.com Signed-off-by: Tomi Valkeinen --- diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c index e0d5336110404..e662aea9d1057 100644 --- a/drivers/gpu/drm/drm_fourcc.c +++ b/drivers/gpu/drm/drm_fourcc.c @@ -491,12 +491,20 @@ EXPORT_SYMBOL(drm_format_info_block_height); */ unsigned int drm_format_info_bpp(const struct drm_format_info *info, int plane) { + unsigned int block_size; + if (!info || plane < 0 || plane >= info->num_planes) return 0; - return info->char_per_block[plane] * 8 / - (drm_format_info_block_width(info, plane) * - drm_format_info_block_height(info, plane)); + block_size = drm_format_info_block_width(info, plane) * + drm_format_info_block_height(info, plane); + + if (info->char_per_block[plane] * 8 % block_size) { + pr_warn("unable to return an integer bpp\n"); + return 0; + } + + return info->char_per_block[plane] * 8 / block_size; } EXPORT_SYMBOL(drm_format_info_bpp);