On Mon, Nov 17, 2025 at 08:11:48PM +0100, Nicolas Frattaroli wrote:
> The new DRM color format property allows userspace to request a specific
> color format on a connector. In turn, this fills the connector state's
> color_format member to switch color formats.
>
> Make drm_bridges consider the color_format set in the connector state
> during the atomic bridge check. Specifically, reject any output bus
> formats that do not correspond to the requested color format.
>
> Signed-off-by: Nicolas Frattaroli <[email protected]>
> ---
> drivers/gpu/drm/drm_bridge.c | 57
> ++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 57 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
> index 8f355df883d8..b7df5cbad832 100644
> --- a/drivers/gpu/drm/drm_bridge.c
> +++ b/drivers/gpu/drm/drm_bridge.c
> @@ -1052,6 +1052,59 @@ static int select_bus_fmt_recursive(struct drm_bridge
> *first_bridge,
> return ret;
> }
>
> +static bool __pure bus_format_is_color_fmt(u32 bus_fmt, enum
> drm_color_format fmt)
> +{
> + if (bus_fmt == MEDIA_BUS_FMT_FIXED)
> + return true;
> +
> + switch (fmt) {
> + case DRM_COLOR_FORMAT_NONE:
> + case DRM_COLOR_FORMAT_AUTO:
> + return true;
> + case DRM_COLOR_FORMAT_RGB444:
> + switch (bus_fmt) {
> + case MEDIA_BUS_FMT_RGB888_1X24:
> + case MEDIA_BUS_FMT_RGB101010_1X30:
> + case MEDIA_BUS_FMT_RGB121212_1X36:
> + case MEDIA_BUS_FMT_RGB161616_1X48:
> + return true;
> + default:
> + return false;
> + }
> + case DRM_COLOR_FORMAT_YCBCR444:
> + switch (bus_fmt) {
> + case MEDIA_BUS_FMT_YUV8_1X24:
> + case MEDIA_BUS_FMT_YUV10_1X30:
> + case MEDIA_BUS_FMT_YUV12_1X36:
> + case MEDIA_BUS_FMT_YUV16_1X48:
> + return true;
> + default:
> + return false;
> + }
> + case DRM_COLOR_FORMAT_YCBCR422:
> + switch (bus_fmt) {
> + case MEDIA_BUS_FMT_UYVY8_1X16:
> + case MEDIA_BUS_FMT_UYVY10_1X20:
> + case MEDIA_BUS_FMT_UYVY12_1X24:
> + return true;
> + default:
> + return false;
> + }
> + case DRM_COLOR_FORMAT_YCBCR420:
> + switch (bus_fmt) {
> + case MEDIA_BUS_FMT_UYYVYY8_0_5X24:
> + case MEDIA_BUS_FMT_UYYVYY10_0_5X30:
> + case MEDIA_BUS_FMT_UYYVYY12_0_5X36:
> + case MEDIA_BUS_FMT_UYYVYY16_0_5X48:
> + return true;
> + default:
> + return false;
> + }
> + }
I'd find this more readable:
if (fmt == DRM_COLOR_FORMAT_NONE || fmt == DRM_COLOR_FORMAT_AUTO)
return true;
switch (bus_fmt) {
case MEDIA_BUS_FMT_RGB888_1X24:
case MEDIA_BUS_FMT_RGB101010_1X30:
case MEDIA_BUS_FMT_RGB121212_1X36:
case MEDIA_BUS_FMT_RGB161616_1X48:
return fmt == DRM_COLOR_FORMAT_RGB444:
case MEDIA_BUS_FMT_YUV8_1X24:
case MEDIA_BUS_FMT_YUV10_1X30:
case MEDIA_BUS_FMT_YUV12_1X36:
case MEDIA_BUS_FMT_YUV16_1X48:
return fmt == DRM_COLOR_FORMAT_YCBCR444;
case MEDIA_BUS_FMT_UYVY8_1X16:
case MEDIA_BUS_FMT_UYVY10_1X20:
case MEDIA_BUS_FMT_UYVY12_1X24:
return fmt == DRM_COLOR_FORMAT_YCBCR422;
case MEDIA_BUS_FMT_UYYVYY8_0_5X24:
case MEDIA_BUS_FMT_UYYVYY10_0_5X30:
case MEDIA_BUS_FMT_UYYVYY12_0_5X36:
case MEDIA_BUS_FMT_UYYVYY16_0_5X48:
return fmt == DRM_COLOR_FORMAT_YCBCR420;
default:
return false;
}
but it could be a matter for personal preference ?
I'm also a bit concerned about the
if (fmt == DRM_COLOR_FORMAT_NONE || fmt == DRM_COLOR_FORMAT_AUTO)
test. What's the difference between NONE and AUTO ? Is it meaningful, or
should the two enumerators be merged into a single one ?
> +
> + return false;
> +}
> +
> /*
> * This function is called by &drm_atomic_bridge_chain_check() just before
> * calling &drm_bridge_funcs.atomic_check() on all elements of the chain.
> @@ -1137,6 +1190,10 @@ drm_atomic_bridge_chain_select_bus_fmts(struct
> drm_bridge *bridge,
> }
>
> for (i = 0; i < num_out_bus_fmts; i++) {
> + if (!bus_format_is_color_fmt(out_bus_fmts[i],
> conn_state->color_format)) {
> + ret = -ENOTSUPP;
> + continue;
> + }
> ret = select_bus_fmt_recursive(bridge, last_bridge, crtc_state,
> conn_state, out_bus_fmts[i]);
> if (ret != -ENOTSUPP)
--
Regards,
Laurent Pinchart
