A hiz surface must be supplied to the hardware when rendering to a depth
buffer with hiz. There are three potential places to store that surface:
1. Allocate a larger intel_region for the depthbuffer, and let the
region's tail be the hiz surface.
2. Allocate a separate intel_region for hiz, and store it as
brw_context state.
3. Allocate a separate intel_region for hiz, and store it in
intel_renderbuffer.
We choose method 3.
Method 1 has not been chosen due to future complications it might cause
when requesting a DRI drawable's depth buffer attachment from X.
Method 2 has not been chosen because storing the hiz region apart from
the depth region makes lazy hiz/depth resolves difficult to implement.
Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Chad Versace <chad@chad-versace.us>
Chad Versace
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