Hi Mike,
Thank you for the patch.
On Fri, Jun 27, 2025 at 04:50:46PM +0200, Mike Looijmans wrote:
> XRGB8888 is the default mode that Xorg will want to use. Add support
> for this to the Zynqmp DisplayPort driver, so that applications can use
> 32-bit framebuffers. This solves that the X server would fail to start
> unless one provided an xorg.conf that sets DefaultDepth to 16.
>
> Signed-off-by: Mike Looijmans <mike.looijm...@topic.nl>
> ---
>
> drivers/gpu/drm/xlnx/zynqmp_disp.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/drivers/gpu/drm/xlnx/zynqmp_disp.c
> b/drivers/gpu/drm/xlnx/zynqmp_disp.c
> index 80d1e499a18d..501428437000 100644
> --- a/drivers/gpu/drm/xlnx/zynqmp_disp.c
> +++ b/drivers/gpu/drm/xlnx/zynqmp_disp.c
> @@ -312,6 +312,11 @@ static const struct zynqmp_disp_format avbuf_gfx_fmts[]
> = {
> .buf_fmt = ZYNQMP_DISP_AV_BUF_FMT_NL_GFX_RGBA8888,
> .swap = true,
> .sf = scaling_factors_888,
> + }, {
> + .drm_fmt = DRM_FORMAT_XRGB8888,
> + .buf_fmt = ZYNQMP_DISP_AV_BUF_FMT_NL_GFX_RGBA8888,
> + .swap = true,
> + .sf = scaling_factors_888,
I'm afraid that's not enough. There's a crucial difference between
DRM_FORMAT_ARGB8888 (already supported by this driver) and
DRM_FORMAT_XRGB8888: for the latter, the 'X' component must be ignored.
The graphics layer is blended on top of the video layer, and the blender
uses both a global alpha parameter and the alpha channel of the graphics
layer for 32-bit RGB formats. This will lead to incorrect operation when
the 'X' component is not set to full opacity.
> }, {
> .drm_fmt = DRM_FORMAT_RGBA8888,
> .buf_fmt = ZYNQMP_DISP_AV_BUF_FMT_NL_GFX_ABGR8888,
--
Regards,
Laurent Pinchart
