Mesa (staging/20.1): radv: Always enable PERFECT_ZPASS_COUNTS.

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Module: Mesa
Branch: staging/20.1
Commit: d7ae273cbfa93ad02914fcf2b776cf862498485a
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=d7ae273cbfa93ad02914fcf2b776cf862498485a

Author: Bas Nieuwenhuizen <bas at basnieuwenhuizen.nl>
Date:   Sun Jul  5 18:57:35 2020 +0200

radv: Always enable PERFECT_ZPASS_COUNTS.

We have an issue with early depth testing and discard, where
non-perfect counts count the tile if the early depth test succeeds.

We could spend a lot of effort to set this conditionally based
on the presence of the two conditions, but in the presence of
inherited queries let's try this first.

Changing PERFECT_ZPASS_COUNTS since I'm pretty sure this has a lower
performance impact than always using late depth testing.

CC: <mesa-stable at lists.freedesktop.org>
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/3218
Reviewed-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5757>
(cherry picked from commit ad913a18b14f25b4f6995cb8a8b0c55c747029d8)

---

 .pick_status.json                | 2 +-
 src/amd/vulkan/radv_cmd_buffer.c | 5 ++++-
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/.pick_status.json b/.pick_status.json
index 5437ff345c7..9337f4a631b 100644
--- a/.pick_status.json
+++ b/.pick_status.json
@@ -121,7 +121,7 @@
         "description": "radv: Always enable PERFECT_ZPASS_COUNTS.",
         "nominated": true,
         "nomination_type": 0,
-        "resolution": 0,
+        "resolution": 1,
         "master_sha": null,
         "because_sha": null
     },
diff --git a/src/amd/vulkan/radv_cmd_buffer.c b/src/amd/vulkan/radv_cmd_buffer.c
index b0ef1e9a08e..1b8aef3eadb 100644
--- a/src/amd/vulkan/radv_cmd_buffer.c
+++ b/src/amd/vulkan/radv_cmd_buffer.c
@@ -2176,8 +2176,11 @@ void radv_set_db_count_control(struct radv_cmd_buffer *cmd_buffer)
 		bool gfx10_perfect = cmd_buffer->device->physical_device->rad_info.chip_class >= GFX10 && has_perfect_queries;
 
 		if (cmd_buffer->device->physical_device->rad_info.chip_class >= GFX7) {
+			/* Always enable PERFECT_ZPASS_COUNTS due to issues with partially
+			 * covered tiles, discards, and early depth testing. For more details,
+			 * see https://gitlab.freedesktop.org/mesa/mesa/-/issues/3218 */
 			db_count_control =
-				S_028004_PERFECT_ZPASS_COUNTS(has_perfect_queries) |
+				S_028004_PERFECT_ZPASS_COUNTS(1) |
 				S_028004_DISABLE_CONSERVATIVE_ZPASS_COUNTS(gfx10_perfect) |
 				S_028004_SAMPLE_RATE(sample_rate) |
 				S_028004_ZPASS_ENABLE(1) |