i965/blorp: allow multisample blorp clears

Previously, we didn't do multisample blorp clears because we couldn't
figure out how to get them to work.  The reason for this was because
we weren't setting the brw_blorp_params num_samples field consistently
with dst.num_samples.  Now that those two fields have been collapsed
down into one, we can do multisample blorp clears.

However, we need to do a few other pieces of bookkeeping to make them
work correctly in all circumstances:

- Since blorp clears may now operate on multisampled window system
  framebuffers, they need to call
  intel_renderbuffer_set_needs_downsample() to ensure that a
  downsample happens before buffer swap (or glReadPixels()).

- When clearing a layered multisample buffer attachment using UMS or
  CMS layout, we need to advance layer by multiples of num_samples
  (since each logical layer is associated with num_samples physical
  layers).

Note: we still don't do multisample fast color clears; more work needs
to be done to enable those.

Reviewed-by: Chad Versace <chad.versace@linux.intel.com>
Reviewed-by: Anuj Phogat <anuj.phogat@gmail.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

diff --git a/src/mesa/drivers/dri/i965/brw_blorp_clear.cpp b/src/mesa/drivers/dri/i965/brw_blorp_clear.cpp
index 01a911b..e9d8518 100644 (file)
--- a/src/mesa/drivers/dri/i965/brw_blorp_clear.cpp
+++ b/src/mesa/drivers/dri/i965/brw_blorp_clear.cpp
@@ -250,7 +250,8 @@ brw_blorp_clear_params::brw_blorp_clear_params(struct brw_context *brw,
     * never larger than the size of a tile, so there is no danger of
     * overflowing beyond the memory belonging to the region.
     */
-   if (irb->mt->fast_clear_state != INTEL_FAST_CLEAR_STATE_NO_MCS &&
+   if (irb->mt->msaa_layout == INTEL_MSAA_LAYOUT_NONE &&
+       irb->mt->fast_clear_state != INTEL_FAST_CLEAR_STATE_NO_MCS &&
        !partial_clear && wm_prog_key.use_simd16_replicated_data &&
        is_color_fast_clear_compatible(brw, format, &ctx->Color.ClearColor)) {
       memset(push_consts, 0xff, 4*sizeof(float));
@@ -514,21 +515,6 @@ bool
 brw_blorp_clear_color(struct brw_context *brw, struct gl_framebuffer *fb,
                       bool partial_clear)
 {
-   /* The constant color clear code doesn't work for multisampled surfaces, so
-    * we need to support falling back to other clear mechanisms.
-    * Unfortunately, our clear code is based on a bitmask that doesn't
-    * distinguish individual color attachments, so we walk the attachments to
-    * see if any require fallback, and fall back for all if any of them need
-    * to.
-    */
-   for (unsigned buf = 0; buf < fb->_NumColorDrawBuffers; buf++) {
-      struct gl_renderbuffer *rb = fb->_ColorDrawBuffers[buf];
-      struct intel_renderbuffer *irb = intel_renderbuffer(rb);
-
-      if (irb && irb->mt->msaa_layout != INTEL_MSAA_LAYOUT_NONE)
-         return false;
-   }
-
    for (unsigned buf = 0; buf < fb->_NumColorDrawBuffers; buf++) {
       struct gl_renderbuffer *rb = fb->_ColorDrawBuffers[buf];
       struct intel_renderbuffer *irb = intel_renderbuffer(rb);
@@ -541,16 +527,25 @@ brw_blorp_clear_color(struct brw_context *brw, struct gl_framebuffer *fb,
          continue;
 
       if (fb->NumLayers > 0) {
-         assert(fb->NumLayers == irb->mt->level[irb->mt_level].depth);
+         unsigned layer_multiplier =
+            (irb->mt->msaa_layout == INTEL_MSAA_LAYOUT_UMS ||
+             irb->mt->msaa_layout == INTEL_MSAA_LAYOUT_CMS) ?
+            irb->mt->num_samples : 1;
+         assert(fb->NumLayers * layer_multiplier ==
+                irb->mt->level[irb->mt_level].depth);
          for (unsigned layer = 0; layer < fb->NumLayers; layer++) {
-            if (!do_single_blorp_clear(brw, fb, rb, buf, partial_clear, layer))
+            if (!do_single_blorp_clear(brw, fb, rb, buf, partial_clear,
+                                       layer * layer_multiplier)) {
                return false;
+            }
          }
       } else {
          unsigned layer = irb->mt_layer;
          if (!do_single_blorp_clear(brw, fb, rb, buf, partial_clear, layer))
             return false;
       }
+
+      intel_renderbuffer_set_needs_downsample(irb);
    }
 
    return true;