i965/gen6: Fix HiZ hang in WebGL Google Maps

Emitting flushes before depth and hiz resolves at the top of blorp's
state emission fixes the hang. Marchesin and I found the fix
experimentally, as opposed to adhering to a documented hardware
workaround.  A more minimal fix likely exists, but this gets the job
done.

Fixes HiZ hangs in the new WebGL Google maps on Sandybridge Chrome OS.
Tested by zooming in and out continuously for 2 hours.

This patch is based on
https://chromium.googlesource.com/chromiumos/overlays/chromiumos-overlay/+/8bc07bb70163c3706fb4ba5f980e57dc942f56dd

CC: [email protected]
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=70740
Signed-off-by: Stéphane Marchesin <[email protected]>
Signed-off-by: Chad Versace <[email protected]>
Reviewed-by: Paul Berry <[email protected]>
Reviewed-by: Kenneth Graunke <[email protected]>
(cherry picked from commit 1a928816a1b717201f3b3cc998a42731b280e6ba)

1 files changed, 15 insertions, 0 deletions

diff --git a/src/mesa/drivers/dri/i965/gen6_blorp.cpp b/src/mesa/drivers/dri/i965/gen6_blorp.cpp
index 8fb8ca14dae..ccb09e7452a 100644
--- a/src/mesa/drivers/dri/i965/gen6_blorp.cpp
+++ b/src/mesa/drivers/dri/i965/gen6_blorp.cpp
@@ -1012,6 +1012,19 @@ gen6_blorp_emit_primitive(struct brw_context *brw,
    ADVANCE_BATCH();
 }
 
+static void
+gen6_emit_hiz_workaround(struct brw_context *brw, enum gen6_hiz_op hiz_op)
+{
+   /* This fixes a HiZ hang in WebGL Google Maps. A more minimal fix likely
+    * exists, but this gets the job done.
+    */
+   if (hiz_op == GEN6_HIZ_OP_DEPTH_RESOLVE ||
+       hiz_op == GEN6_HIZ_OP_HIZ_RESOLVE) {
+      brw->batch.need_workaround_flush = true;
+      intel_emit_post_sync_nonzero_flush(brw);
+      intel_emit_depth_stall_flushes(brw);
+   }
+}
 
 /**
  * \brief Execute a blit or render pass operation.
@@ -1034,6 +1047,8 @@ gen6_blorp_exec(struct brw_context *brw,
    uint32_t wm_bind_bo_offset = 0;
 
    uint32_t prog_offset = params->get_wm_prog(brw, &prog_data);
+
+   gen6_emit_hiz_workaround(brw, params->hiz_op);
    gen6_emit_3dstate_multisample(brw, params->num_samples);
    gen6_emit_3dstate_sample_mask(brw, params->num_samples, 1.0, false, ~0u);
    gen6_blorp_emit_state_base_address(brw, params);