[Mesa-dev] [PATCH 04/17] i965/miptree: Initialize the indirect clear color to zero

[Jason Ekstrand]

On Thu, May 3, 2018 at 12:03 PM, Nanley Chery <nanleychery at gmail.com> wrote:

> The indirect clear color isn't correctly tracked in
> intel_miptree::fast_clear_color. The initial value of ::fast_clear_color
> is zero, while that of the indirect clear color is undefined or
> non-zero.
>
> Topi Pohjolainen discovered this issue with MCS buffers. This issue is
> apparent when fast-clearing an MCS buffer for the first time with
> glClearColor = {0.0,}. Although the indirect clear color is non-zero,
> the initial aux state of the MCS is CLEAR and the tracked clear color is
> zero, so we avoid updating the indirect clear color with {0.0,}.
>
> Make the indirect clear color match the initial value of
> ::fast_clear_color.
>
> ---
>
> Hey Topi,
>
> Just FYI, this patch should fix the MCS bug you reported earlier.
>
>  src/mesa/drivers/dri/i965/intel_mipmap_tree.c | 33
> ++++++++++++++++++---------
>  1 file changed, 22 insertions(+), 11 deletions(-)
>
> diff --git a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
> b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
> index 5d3ee569bd8..e70c9ff1ef4 100644
> --- a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
> +++ b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
> @@ -978,11 +978,11 @@ create_ccs_buf_for_image(struct brw_context *brw,
>      * system with CCS, we don't have the extra space at the end of the aux
>      * buffer. So create a new bo here that will store that clear color.
>      */
> -   const struct gen_device_info *devinfo = &brw->screen->devinfo;
> -   if (devinfo->gen >= 10) {
> +   if (brw->isl_dev.ss.clear_color_state_size > 0) {
>        mt->aux_buf->clear_color_bo =
> -         brw_bo_alloc(brw->bufmgr, "clear_color_bo",
> -                      brw->isl_dev.ss.clear_color_state_size);
> +         brw_bo_alloc_tiled(brw->bufmgr, "clear_color_bo",
> +                            brw->isl_dev.ss.clear_color_state_size,
> +                            I915_TILING_NONE, 0, BO_ALLOC_ZEROED);
>        if (!mt->aux_buf->clear_color_bo) {
>           free(mt->aux_buf);
>           mt->aux_buf = NULL;
> @@ -1673,9 +1673,9 @@ intel_alloc_aux_buffer(struct brw_context *brw,
>
>     buf->size = aux_surf->size;
>
> -   const struct gen_device_info *devinfo = &brw->screen->devinfo;
> -   if (devinfo->gen >= 10) {
> -      /* On CNL, instead of setting the clear color in the SURFACE_STATE,
> we
> +   const bool has_indirect_clear = brw->isl_dev.ss.clear_color_state_size
> > 0;
> +   if (has_indirect_clear) {
> +      /* On CNL+, instead of setting the clear color in the
> SURFACE_STATE, we
>         * will set a pointer to a dword somewhere that contains the color.
> So,
>         * allocate the space for the clear color value here on the aux
> buffer.
>         */
> @@ -1698,7 +1698,8 @@ intel_alloc_aux_buffer(struct brw_context *brw,
>     }
>
>     /* Initialize the bo to the desired value */
> -   if (wants_memset) {
> +   const bool needs_memset = wants_memset || has_indirect_clear;
> +   if (needs_memset) {
>

I don't think the temporary bool is doing you any good.  just doing

if (wants_memset || has_indirect_clear) {
   /* map */
   if (wants_memset) ...
   if (has_indirect_clear) ...
}

is simpler.  This needs_memset thing makes it look like we're going "Ha!
You have an indirect clear so you're getting a memset even though you
didn't ask for one!"


>        assert(!(alloc_flags & BO_ALLOC_BUSY));
>
>        void *map = brw_bo_map(brw, buf->bo, MAP_WRITE | MAP_RAW);
> @@ -1706,11 +1707,21 @@ intel_alloc_aux_buffer(struct brw_context *brw,
>           intel_miptree_aux_buffer_free(buf);
>           return NULL;
>        }
> -      memset(map, memset_value, mt->aux_buf->size);
> +
> +      /* Memset the aux_surf portion of the BO. */
> +      if (wants_memset)
> +         memset(map, memset_value, aux_surf->size);
> +
> +      /* Zero the indirect clear color to match ::fast_clear_color. */
> +      if (has_indirect_clear) {
> +         memset((char *)map + buf->clear_color_offset, 0,
> +                brw->isl_dev.ss.clear_color_state_size);
> +      }
> +
>        brw_bo_unmap(buf->bo);
>     }
>
> -   if (devinfo->gen >= 10) {
> +   if (has_indirect_clear) {
>        buf->clear_color_bo = buf->bo;
>        brw_bo_reference(buf->clear_color_bo);
>     }
> @@ -1869,7 +1880,7 @@ intel_miptree_alloc_hiz(struct brw_context *brw,
>        isl_surf_get_hiz_surf(&brw->isl_dev, &mt->surf, &temp_hiz_surf);
>     assert(ok);
>
> -   const uint32_t alloc_flags = BO_ALLOC_BUSY;
> +   const uint32_t alloc_flags = 0;
>     mt->aux_buf = intel_alloc_aux_buffer(brw, "hiz-miptree",
> &temp_hiz_surf,
>                                          alloc_flags, false, 0, mt);
>
> --
> 2.16.2
>
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