[Mesa-dev] [PATCH] anv: remove support for d32_sfloat_s8_uint

[Kenneth Graunke]

On Friday, August 5, 2016 6:23:47 PM PDT Lionel Landwerlin wrote:
> On 05/08/16 18:08, Jason Ekstrand wrote:
> >
> > On Aug 5, 2016 9:49 AM, "Lionel Landwerlin" 
> > <lionel.g.landwerlin at intel.com <mailto:lionel.g.landwerlin at intel.com>> 
> > wrote:
> > >
> > > It doesn't seem like we have any support for 32bits of something + 
> > 8bits of
> > > something else.
> >
> > Not quite. Depth-stencil formats are weird because they describe two 
> > different things at the same time. In our hardware (post Sandy Bridge) 
> > the depth and stencil components are actually stored in different 
> > surfaces but in the same VkImage.  We certainly can handle 32-bit 
> > depth with stencil, we just need to get the blits working.Th
> >
> 
> Thanks for the explanation. Would that be 
> ISL_FORMAT_R32_FLOAT_X8X24_TYPELESS then?
> 
> -
> Lionel

R32_FLOAT_X8X24_TYPELESS is indeed the format for packed 32-bit depth
and 8-bit stencil combined.  But, as Jason said, we don't actually use
that in the hardware...we use R32_FLOAT and separately R8_UINT.

Because things are stored separately, we usually have to blit depth
and then blit stencil...so one API-level blit turns into two blits
in the driver.
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