| Message ID | 20250212-xilinx-formats-v3-1-90d0fe106995@ideasonboard.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm: Add new pixel formats for Xilinx Zynqmp | expand |
Hi Tomi, Thank you for the patch. On Wed, Feb 12, 2025 at 04:56:05PM +0200, Tomi Valkeinen wrote: > 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_XV15's (not yet in upstream) 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. > > Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com> > --- > drivers/gpu/drm/drm_fourcc.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c > index 3a94ca211f9c..1e9afbf6ef99 100644 > --- a/drivers/gpu/drm/drm_fourcc.c > +++ b/drivers/gpu/drm/drm_fourcc.c > @@ -457,6 +457,13 @@ unsigned int drm_format_info_bpp(const struct drm_format_info *info, int plane) > if (!info || plane < 0 || plane >= info->num_planes) > return 0; > > + if (info->char_per_block[plane] * 8 % > + (drm_format_info_block_width(info, plane) * > + drm_format_info_block_height(info, plane))) { Can you cache drm_format_info_block_width(info, plane) * drm_format_info_block_height(info, plane) in a local variable to avoid computing it twice ? > + pr_warn("unable to return an integer bpp\n"); It would be nice to print the warning in the context of the drm device, but we don't have the required structure here. Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> > + return 0; > + } > + > return info->char_per_block[plane] * 8 / > (drm_format_info_block_width(info, plane) * > drm_format_info_block_height(info, plane));
diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c index 3a94ca211f9c..1e9afbf6ef99 100644 --- a/drivers/gpu/drm/drm_fourcc.c +++ b/drivers/gpu/drm/drm_fourcc.c @@ -457,6 +457,13 @@ unsigned int drm_format_info_bpp(const struct drm_format_info *info, int plane) if (!info || plane < 0 || plane >= info->num_planes) return 0; + if (info->char_per_block[plane] * 8 % + (drm_format_info_block_width(info, plane) * + drm_format_info_block_height(info, plane))) { + pr_warn("unable to return an integer bpp\n"); + return 0; + } + return info->char_per_block[plane] * 8 / (drm_format_info_block_width(info, plane) * drm_format_info_block_height(info, plane));
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_XV15's (not yet in upstream) 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. Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com> --- drivers/gpu/drm/drm_fourcc.c | 7 +++++++ 1 file changed, 7 insertions(+)