[Mesa-dev] [PATCH] i965: do not fallback to linear tiling for depth/stencil surfaces

[Kenneth Graunke]

On Thursday, September 7, 2017 11:44:04 PM PDT Iago Toral Quiroga wrote:
> It is not supported by the hardware and the driver assumes
> W-tiling for stencil and Y-tiling for depth everywhere anyway.
> 
> This fixes a regression in a CTS test introduced with commit
> 4ea63fab77f0 that started applying re-tiling for these surfaces
> in certain scenarios.
> 
> Fixes:
> KHR-GL45.direct_state_access.renderbuffers_storage
> ---
>  src/mesa/drivers/dri/i965/intel_mipmap_tree.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
> index 79afdc5342..cfc1212353 100644
> --- a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
> +++ b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
> @@ -572,9 +572,13 @@ make_surface(struct brw_context *brw, GLenum target, mesa_format format,
>  
>     /* In case caller doesn't specifically request Y-tiling (needed
>      * unconditionally for depth), check for corner cases needing special
> -    * treatment.
> +    * treatment. Stencil and depth surfaces are always W  and Y tiled
> +    * respectively, so we should not attempt to retile them to different
> +    * layouts.
>      */
> -   if (tiling_flags & ~ISL_TILING_Y0_BIT) {

Based on Topi's comment, it sounds like depth surfaces should be passing
tiling_flags == ISL_TILING_Y0_BIT, so we shouldn't hit this for depth.

Separate stencil passes ISL_TILING_W_BIT, so I think you're right that
it'll incorrectly hit this case.  Perhaps we need to just change it to:

   if (tiling_flags & ~(ISL_TILING_Y0_BIT | ISL_TILING_W_BIT))

...?  Though, basing it on usage doesn't seem bad either...

> +   bool is_depth_stencil = mt->surf.usage &
> +      (ISL_SURF_USAGE_STENCIL_BIT | ISL_SURF_USAGE_DEPTH_BIT);
> +   if (!is_depth_stencil && (tiling_flags & ~ISL_TILING_Y0_BIT)) {
>        if (need_to_retile_as_linear(brw, mt->surf.row_pitch,
>                                     mt->surf.tiling, mt->surf.samples)) {
>           init_info.tiling_flags = 1u << ISL_TILING_LINEAR;
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 833 bytes
Desc: This is a digitally signed message part.
URL: <https://lists.freedesktop.org/archives/mesa-dev/attachments/20170908/1b409e7a/attachment.sig>