On Wed, Jan 28, 2026 at 07:25:28PM +0200, Tomi Valkeinen wrote: > Add greyscale Y8 format. > > The 8-bit greyscale format has been discussed before, and the earlier > guidance was to use DRM_FORMAT_R8, as a single-channel 8-bit pixel. > > However, adding DRM_FORMAT_Y8 makes sense, we can mark it as 'is_yuv' in > the drm_format_info, and this can help the drivers handle e.g. > full/limited range. This will distinguish two single-channel formats: > R8, which is a RGB format with the same value for all components, and > Y8, which is a Y-only YCbCr format, with Cb and Cr being neutral. > > Acked-by: Dmitry Baryshkov <[email protected]> > Reviewed-by: Pekka Paalanen <[email protected]> > Reviewed-by: Vishal Sagar <[email protected]> > Signed-off-by: Tomi Valkeinen <[email protected]>
Reviewed-by: Laurent Pinchart <[email protected]> > --- > drivers/gpu/drm/drm_fourcc.c | 1 + > include/uapi/drm/drm_fourcc.h | 9 +++++++++ > 2 files changed, 10 insertions(+) > > diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c > index b22ef86428a1..a39b9d7a5b62 100644 > --- a/drivers/gpu/drm/drm_fourcc.c > +++ b/drivers/gpu/drm/drm_fourcc.c > @@ -275,6 +275,7 @@ const struct drm_format_info *__drm_format_info(u32 > format) > { .format = DRM_FORMAT_YVU422, .depth = 0, > .num_planes = 3, .cpp = { 1, 1, 1 }, .hsub = 2, .vsub = 1, .is_yuv = true }, > { .format = DRM_FORMAT_YUV444, .depth = 0, > .num_planes = 3, .cpp = { 1, 1, 1 }, .hsub = 1, .vsub = 1, .is_yuv = true }, > { .format = DRM_FORMAT_YVU444, .depth = 0, > .num_planes = 3, .cpp = { 1, 1, 1 }, .hsub = 1, .vsub = 1, .is_yuv = true }, > + { .format = DRM_FORMAT_Y8, .depth = 8, > .num_planes = 1, .cpp = { 1, 0, 0 }, .hsub = 1, .vsub = 1, .is_yuv = true }, > { .format = DRM_FORMAT_NV12, .depth = 0, > .num_planes = 2, .cpp = { 1, 2, 0 }, .hsub = 2, .vsub = 2, .is_yuv = true }, > { .format = DRM_FORMAT_NV21, .depth = 0, > .num_planes = 2, .cpp = { 1, 2, 0 }, .hsub = 2, .vsub = 2, .is_yuv = true }, > { .format = DRM_FORMAT_NV16, .depth = 0, > .num_planes = 2, .cpp = { 1, 2, 0 }, .hsub = 2, .vsub = 1, .is_yuv = true }, > diff --git a/include/uapi/drm/drm_fourcc.h b/include/uapi/drm/drm_fourcc.h > index 6c786701238e..e4451668499a 100644 > --- a/include/uapi/drm/drm_fourcc.h > +++ b/include/uapi/drm/drm_fourcc.h > @@ -459,6 +459,15 @@ extern "C" { > #define DRM_FORMAT_YUV444 fourcc_code('Y', 'U', '2', '4') /* > non-subsampled Cb (1) and Cr (2) planes */ > #define DRM_FORMAT_YVU444 fourcc_code('Y', 'V', '2', '4') /* > non-subsampled Cr (1) and Cb (2) planes */ > > +/* > + * Y-only (greyscale) formats > + * > + * The Y-only formats are handled similarly to the YCbCr formats in the > display > + * pipeline, with the Cb and Cr implicitly neutral (0.0 in nominal values). > This > + * also means that COLOR_RANGE property applies to the Y-only formats. > + */ > + > +#define DRM_FORMAT_Y8 fourcc_code('G', 'R', 'E', 'Y') /* > 8-bit Y-only */ > > /* > * Format Modifiers: -- Regards, Laurent Pinchart
