[Mesa-dev] [PATCH 2/2] i965/miptree: Create a disable CCS flag

[Chad Versace]

On Sun 01 Jan 2017, Ben Widawsky wrote:
> Cc: Topi Pohjolainen <topi.pohjolainen at intel.com>
> Cc: Chad Versace <chadversary at chromium.org>
> Signed-off-by: Ben Widawsky <ben at bwidawsk.net>
> ---
>  src/mesa/drivers/dri/i965/brw_blorp.c         |  2 +-
>  src/mesa/drivers/dri/i965/brw_draw.c          |  3 ++-
>  src/mesa/drivers/dri/i965/intel_mipmap_tree.c | 21 ++++++++++-----------
>  src/mesa/drivers/dri/i965/intel_mipmap_tree.h | 10 +++-------
>  4 files changed, 16 insertions(+), 20 deletions(-)


> @@ -2334,19 +2334,18 @@ intel_miptree_make_shareable(struct brw_context *brw,
>  
>     if (mt->mcs_buf) {
>        intel_miptree_all_slices_resolve_color(brw, mt, 0);
> -      mt->no_ccs = true;
> +      mt->aux_disable |= (INTEL_AUX_DISABLE_CCS | INTEL_AUX_DISABLE_MCS);
>        drm_intel_bo_unreference(mt->mcs_buf->bo);
>        free(mt->mcs_buf);
>        mt->mcs_buf = NULL;
>     }
>  
>     if (mt->hiz_buf) {
> +      mt->aux_disable |= INTEL_AUX_DISABLE_HIZ;
>        intel_miptree_all_slices_resolve_depth(brw, mt);
>        intel_miptree_hiz_buffer_free(mt->hiz_buf);
>        mt->hiz_buf = NULL;
>     }
> -
> -   mt->aux_disable = INTEL_AUX_DISABLE_ALL;
>  }

All look goods to me except the above hunk. As written, in some
instances the driver will allocate (and use) the aux surface *after*
intel_miptree_make_shareable() unshares the miptree. To fix that, the
mt->aux_disable bits must be set unconditionally, outside the if's.

The problem is that the driver sometimes allocates the aux surfaces
lazily. For evidence, grep for all instances of
intel_miptree_alloc_hiz() and intel_miptree_alloc_non_msrt_mcs() outside
of intel_mipmap_tree.c. If the code calls intel_miptree_make_shareable()
on a miptree for which the aux surface has not yet been allocated yet,
then intel_miptree_make_shareable() fails to set the disable bit.