GUD_PIXEL_FORMAT_ARGB8888 should be deprecated, doesn't work

[notro]

GUD_PIXEL_FORMAT_ARGB8888 should never have been added (have no idea what I was thinking). GUD only supports one plane and there's no "background" color so it doesn't make any sense to have an alpha color. On top of that it doesn't work for some reason.

Remove it from gud_from_fourcc() and gud_to_fourcc() and add a comment in include/drm/gud.h.

[oniongarlic]

Was wondering about alpha support, don't know if it is possible, but I would have a use case for splitting the output on dual display devices (Pi4/5) so one output would be key (rgb) and the other mask (alpha). Would something like that even be possible ?

[notro]

Was wondering about alpha support, don't know if it is possible, but I would have a use case for splitting the output on dual display devices (Pi4/5) so one output would be key (rgb) and the other mask (alpha). Would something like that even be possible ?

You would have to write a custom gadget.
But how would you use the mask? GUD only supports one plane and there's no way to set a background color.

[oniongarlic]

So framebuffers don't support RGBA ?

[notro]

They can do that if there is support for multiple planes, or if it's possible to set a background color. Something has to be visible through that transparent pixel.