[Mesa-dev] [Intel-gfx] [PATCH] dri3, i915, i965: Add __DRI_IMAGE_FOURCC_SARGB8888

Ville Syrjälä ville.syrjala at linux.intel.com
Fri Nov 22 15:05:04 PST 2013

On Fri, Nov 22, 2013 at 02:12:13PM -0800, Kristian Høgsberg wrote:
> On Fri, Nov 22, 2013 at 05:17:37PM +0100, Daniel Vetter wrote:
> > On Fri, Nov 22, 2013 at 12:01 PM, Keith Packard <keithp at keithp.com> wrote:
> > > Daniel Vetter <daniel at ffwll.ch> writes:
> > >
> > >> Hm, where do we have the canonical source for all these fourcc codes? I'm
> > >> asking since we have our own copy in the kernel as drm_fourcc.h, and that
> > >> one is part of the userspace ABI since we use it to pass around
> > >> framebuffer formats and format lists.
> > >
> > > I think it's the kernel? I really don't know, as the whole notion of
> > > fourcc codes seems crazy to me...
> > >
> > > Feel free to steal this code and stick it in the kernel if you like.
> > 
> > Well, I wasn't ever in favour of using fourcc codes since they're just
> > not standardized at all, highly redundant in some cases and also miss
> > lots of stuff we actually need (like all the rgb formats).
> These drm codes are not fourcc codes in any other way than that
> they're defined by creating a 32 bit value by picking four characters.
> I don't know what PTSD triggers people have from hearing "fourcc", but
> it seems severe.  Forget all that, these codes are DRM specific
> defines that are not inteded to match anything anybody else does.  It
> doesn't matter if these match of conflict with v4l, fourcc.org,
> wikipedia.org or what the amiga did.  They're just tokens that let us
> define succintly what the pixel format of a kms framebuffer is and
> tell the kernel.
> I don't know what else you'd propose?  Pass an X visual in the ioctl?
> An EGL config?  This is our name space, we can add stuff as we need
> (as Keith is doing here). include/uapi/drm/drm_fourcc.h is the
> canonical source for these values and we should add
> DRM_FORMAT_SARGB8888 there to make sure we don't clash.

What is this format anyway? -ENODOCS

If its just an srgb version of ARGB8888, then I wouldn't really want it
in drm_fourcc.h. I expect colorspacy stuff will be handled by various
crtc/plane properties in the kernel so we don't need to encode that
stuff into the fb format.

Ville Syrjälä
Intel OTC

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