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: mesa-stable@lists.freedesktop.org
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=70740
Signed-off-by: Stéphane Marchesin <marcheu@chromium.org>
Signed-off-by: Chad Versace <chad.versace@linux.intel.com>
Reviewed-by: Paul Berry <stereotype441@gmail.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

diff --git a/src/mesa/drivers/dri/i965/gen6_blorp.cpp b/src/mesa/drivers/dri/i965/gen6_blorp.cpp
index 6a5841f78c00a726f09cdf75fe99acddb6117903..441d61fb018d7a78211b905c9a338bc2191a4c8e 100644 (file)
--- 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->dst.num_samples);
    gen6_emit_3dstate_sample_mask(brw,
                                  params->dst.num_samples > 1 ?