On Mon, 4 Feb 2019 22:10:00 +0000 "Strasser, Kevin" <kevin.stras...@intel.com> wrote:
> Pekka Paalanen wrote: > > is there a reason you need these in the wl_shm format list? That is, > > essentially for software rendered stuff? > > > > The zwp_linux_dmabuf extension which GL and Vulkan implementations are > > using only says the format is a drm_fourcc format, so there is no need > > to explicitly add the format there. > > > > Wayland does not need to support a pixel format for a compositor to be > > able to use that format on scanout/KMS. You only need the pixel format > > through Wayland if you want to have client buffers be able to hit the > > composite-bypass path and be scanned out directly on e.g. overlay or > > primary planes. > > That is what I was trying to achieve, offering applications fp16 scan out > buffers. I'm not aware of any explicit requirement for adding the wl_shm > format > outside of Mesa's Walyand egl driver, which includes WL_SHM_FORMAT* for each > supported visual (I think just for the swrast path). That should really be only the software rendering paths and they use wl_shm specifically. The hardware rendering paths should use DRM formats (drm_fourcc), everything is kind of standardising around those these days. > > wl_shm buffers are never expected to be scanout-capable because of the way > > their memory is allocated, so adding the format there does not help. > > zwp_linux_dmabuf is where the format is needed. > > > > Or do you need the formats for cursor planes? > > I don't believe fp16 would be needed for cursor planes. Right. Or maybe HDR cursors? Let's not go there yet. ;-) Thanks, pq > > Wayland and Pixman have no connection whatsoever. You don't need > > support in Pixman to have these added into wl_shm set of formats. > > > > Implementing compositor support for them may or may not need Pixman > > support, depending on the compositor. Weston for example has two > > renderers, and the GL-renderer could well support these formats without > > Pixman supporting them. The Pixman renderer OTOH could not. Weston's > > renderers are allowed to support different sets of formats, so Pixman > > support is not necessary for Weston support. > > > > As a small detail, patch 2 is ok, but not necessary. Those tests test > > wayland-scanner, and adding this new format to example.xml does not > > really add anything to the test. > > Ok, thanks for the detailed explanation. > > Thanks, > Kevin
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