[Mesa-dev] [PATCH v2 22/27] i965/miptree: Allocate mcs_buf for an image's CCS

Chad Versace chadversary at chromium.org
Wed Jul 12 18:05:27 UTC 2017


On Thu 29 Jun 2017, Jason Ekstrand wrote:
> From: Ben Widawsky <ben at bwidawsk.net>
>
> This code will disable actually creating these buffers for the scanout,
> but it puts the allocation in place.
>
> Primarily this patch is split out for review, it can be squashed in
> later if preferred.
>
> v2:
> assert(mt->offset == 0) in ccs creation (as requested by Topi)
> Remove bogus is_scanout check in miptree_release
>
> v3:
> Remove is_scanout assert in intel_miptree_create. It doesn't work with
> latest codebase - not sure it ever should have worked.
>
> v4:
> assert(mt->last_level == 0) and assert(mt->first_level == 0) in ccs setup
> (Topi)
>
> v5 (Jason Ekstrand):
>  - Base the decision to allocate a CCS on the image modifier
>
> Signed-off-by: Ben Widawsky <ben at bwidawsk.net>
> Acked-by: Daniel Stone <daniels at collabora.com>
> Reviewed-by: Topi Pohjolainen <topi.pohjolainen at intel.com>
> ---
>  src/mesa/drivers/dri/i965/intel_mipmap_tree.c | 123 +++++++++++++++++++++++---
>  1 file changed, 113 insertions(+), 10 deletions(-)
>
> diff --git a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
> index 575f04f..7a22cbf 100644
> --- a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
> +++ b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
> @@ -59,6 +59,11 @@ intel_miptree_alloc_mcs(struct brw_context *brw,
>                          struct intel_mipmap_tree *mt,
>                          GLuint num_samples);
>
> +static void
> +intel_miptree_init_mcs(struct brw_context *brw,
> +                       struct intel_mipmap_tree *mt,
> +                       int init_value);
> +
>  /**
>   * Determine which MSAA layout should be used by the MSAA surface being
>   * created, based on the chip generation and the surface type.
> @@ -1026,6 +1031,67 @@ miptree_create_for_planar_image(struct brw_context *brw,
>     return planar_mt;
>  }
>
> +static bool
> +create_ccs_buf_for_image(struct brw_context *brw,
> +                         __DRIimage *image,
> +                         struct intel_mipmap_tree *mt,
> +                         enum isl_aux_state initial_state)
> +{
> +   struct isl_surf temp_main_surf, temp_ccs_surf;
> +
> +   /* There isn't anything specifically wrong with there being an offset, in
> +    * which case, the CCS miptree's offset should be mt->offset +
> +    * image->aux_offset. However, the code today only will have an offset when
> +    * this miptree is pointing to a slice from another miptree, and in that case
> +    * we'd need to offset within the AUX CCS buffer properly. It's questionable
> +    * whether our code handles that case properly, and since it can never happen
> +    * for scanout, just use the assertion to prevent it.
> +    */
> +   assert(mt->offset == 0);
> +
> +   /* CCS is only supported for very simple miptrees */
> +   assert(image->aux_offset && image->aux_pitch);

Why require that aux_offset > 0? Why reject images where the aux surface
precedes the primary surface? This rejection seems arbitrary.  Please
add a little explanatory comment.

Also, please use `!= 0` above, to be consistent with the assertions
above and below this one.

> +   assert(image->tile_x == 0 && image->tile_y == 0);
> +   assert(mt->num_samples <= 1);
> +   assert(mt->first_level == 0);
> +   assert(mt->last_level == 0);
> +   assert(mt->logical_depth0 == 1);
> +
> +   /* We shouldn't already have a CCS */
> +   assert(!mt->mcs_buf);
> +
> +   intel_miptree_get_isl_surf(brw, mt, &temp_main_surf);
> +   if (!isl_surf_get_ccs_surf(&brw->isl_dev, &temp_main_surf, &temp_ccs_surf))
> +      return false;
> +
> +   assert(temp_ccs_surf.size <= image->bo->size - image->aux_offset);

This assertion appears invalid, vulnerable to underflow when the
incoming aux_offset is wrong and too large. It needs to be preceded
by assert(image->aux_offset < image->bo->size).

> +   assert(temp_ccs_surf.row_pitch <= image->aux_pitch);
> +
> +   mt->mcs_buf = calloc(sizeof(*mt->mcs_buf), 1);
> +   if (mt->mcs_buf == NULL)
> +      return false;
> +
> +   mt->aux_state = create_aux_state_map(mt, initial_state);
> +   if (!mt->aux_state) {
> +      free(mt->mcs_buf);
> +      mt->mcs_buf = NULL;
> +      return false;
> +   }
> +
> +   mt->mcs_buf->bo = image->bo;
> +   brw_bo_reference(image->bo);
> +
> +   mt->mcs_buf->offset = image->aux_offset;
> +   mt->mcs_buf->size = image->bo->size - image->aux_offset;
> +   mt->mcs_buf->pitch = image->aux_pitch;
> +   mt->mcs_buf->qpitch = 0;
> +
> +   intel_miptree_init_mcs(brw, mt, 0);

Ack! This may be an imported image, and therefore the aux surface content is
significant. But this patch clobbers it! What am I misunderstanding?

> +   mt->msaa_layout = INTEL_MSAA_LAYOUT_CMS;

I flinched when I saw mt->msaa_layout = INTEL_MSAA_LAYOUT_CMS. And the comments
below make me sad. Anyway, fixing that is a task for another day.

    bool
    intel_miptree_is_lossless_compressed(const struct brw_context *brw,
                                         const struct intel_mipmap_tree *mt)
    {
       ...

       /* Single sample compression is represented re-using msaa compression
        * layout type: "Compressed Multisampled Surfaces".
        */
       if (mt->msaa_layout != INTEL_MSAA_LAYOUT_CMS)
          return false;

       /* And finally distinguish between msaa and single sample case. */
       return mt->num_samples <= 1;
    }

> +
> +   return true;
> +}
> +
>  struct intel_mipmap_tree *
>  intel_miptree_create_for_dri_image(struct brw_context *brw,
>                                     __DRIimage *image, GLenum target,
> @@ -1072,15 +1138,26 @@ intel_miptree_create_for_dri_image(struct brw_context *brw,
>     if (!brw->ctx.TextureFormatSupported[format])
>        return NULL;
>
> +   const struct isl_drm_modifier_info *mod_info =
> +      isl_drm_modifier_get_info(image->modifier);
> +
> +   uint32_t mt_layout_flags = 0;
> +
> +   /* If this image comes in from a window system, then it may get promoted to
> +    * scanout at any time so we need to set the flag accordingly.
> +    */
> +   if (is_winsys_image)
> +      mt_layout_flags |= MIPTREE_LAYOUT_FOR_SCANOUT;
> +
>     /* If this image comes in from a window system, we have different
>      * requirements than if it comes in via an EGL import operation.  Window
>      * system images can use any form of auxiliary compression we wish because
>      * they get "flushed" before being handed off to the window system and we
> -    * have the opportunity to do resolves.  Window system buffers also may be
> -    * used for scanout so we need to flag that appropriately.
> +    * have the opportunity to do resolves.
>      */
> -   const uint32_t mt_layout_flags =
> -      is_winsys_image ? MIPTREE_LAYOUT_FOR_SCANOUT : MIPTREE_LAYOUT_DISABLE_AUX;
> +   if (!is_winsys_image &&
> +       (!mod_info || mod_info->aux_usage == ISL_AUX_USAGE_NONE))
> +      mt_layout_flags |= MIPTREE_LAYOUT_DISABLE_AUX;
>
>     /* Disable creation of the texture's aux buffers because the driver exposes
>      * no EGL API to manage them. That is, there is no API for resolving the aux
> @@ -1117,15 +1194,41 @@ intel_miptree_create_for_dri_image(struct brw_context *brw,
>        }
>     }
>
> -   /* Since CCS_E can compress more than just clear color, we create the CCS
> -    * for it up-front.  For CCS_D which only compresses clears, we create the
> -    * CCS on-demand when a clear occurs that wants one.
> -    */
> -   if (mt->aux_usage == ISL_AUX_USAGE_CCS_E) {
> -      if (!intel_miptree_alloc_ccs(brw, mt)) {
> +   if (mod_info && mod_info->aux_usage != ISL_AUX_USAGE_NONE) {
> +      assert(mod_info->aux_usage == ISL_AUX_USAGE_CCS_E);
> +
> +      mt->aux_usage = mod_info->aux_usage;

Convince me that it's safe to clobber mt->aux_usage here. I will be easily convinced.

> +      /* If we are a window system buffer, then we can support fast-clears
> +       * even if the modifier doesn't support them by doing a partial resolve
> +       * as part of the flush operation.
> +       */
> +      mt->supports_fast_clear =
> +         is_winsys_image || mod_info->supports_clear_color;
> +
> +      /* We don't know the actual state of the surface when we get it but we
> +       * can make a pretty good guess based on the modifier.  What we do know
> +       * for sure is that it isn't in the AUX_INVALID state, so we just assume
> +       * a worst case of compression.
> +       */
> +      enum isl_aux_state initial_state =
> +         mod_info->supports_clear_color ? ISL_AUX_STATE_COMPRESSED_CLEAR :
> +                                          ISL_AUX_STATE_COMPRESSED_NO_CLEAR;
> +
> +      if (!create_ccs_buf_for_image(brw, image, mt, initial_state)) {
>           intel_miptree_release(&mt);
>           return NULL;
>        }
> +   } else if (mt->aux_usage != ISL_AUX_USAGE_NONE) {
> +      /* Since CCS_E can compress more than just clear color, we create the
> +       * CCS for it up-front.  For CCS_D which only compresses clears, we
> +       * create the CCS on-demand when a clear occurs that wants one.
> +       */
> +      if (mt->aux_usage == ISL_AUX_USAGE_CCS_E) {

The else-if-if chain here is ugly. The inner if's condition should replace the
outer else-if's condition.

> +         if (!intel_miptree_alloc_ccs(brw, mt)) {
> +            intel_miptree_release(&mt);
> +            return NULL;
> +         }
> +      }
>     }
>
>     return mt;
> --
> 2.5.0.400.gff86faf
>
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