From 2d7f1d9edc4b139c2a4296788f5677f01340a740 Mon Sep 17 00:00:00 2001
From: Jamie Nicol <jnicol@mozilla.com>
Date: Wed, 15 Feb 2023 15:23:56 +0000
Subject: [PATCH] Bug 1816872 - Allow partial picture cache tile invalidation
 on recent Mali devices. r=gfx-reviewers,nical

We previously blocked partial picture cache tile invalidation on
Mali-T and Mali-G devices due to several bugs. These issues no longer
appear to reproduce on recent Mali GPUs: eg G77, G78, G710 which are
all "Valhall" architecture. This patch therefore keeps the workaround
for all Midgard and Bifrost GPUs, but removes it for others.

Differential Revision: https://phabricator.services.mozilla.com/D169890
---
 gfx/wr/webrender/src/device/gl.rs | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/gfx/wr/webrender/src/device/gl.rs b/gfx/wr/webrender/src/device/gl.rs
index 7eaa8d28bb59..f5fc18f24839 100644
--- a/gfx/wr/webrender/src/device/gl.rs
+++ b/gfx/wr/webrender/src/device/gl.rs
@@ -1728,12 +1728,17 @@ impl Device {
         // from a non-zero offset within a PBO to fail. See bug 1603783.
         let supports_nonzero_pbo_offsets = !is_macos;
 
-        // On Mali-Gxx and Txxx there is a driver bug when rendering partial updates to
-        // offscreen render targets, so we must ensure we render to the entire target.
-        // See bug 1663355.
-        let is_mali_g = renderer_name.starts_with("Mali-G");
-        let is_mali_t = renderer_name.starts_with("Mali-T");
-        let supports_render_target_partial_update = !is_mali_g && !is_mali_t;
+        // We have encountered several issues when only partially updating render targets on a
+        // variety of Mali GPUs. As a precaution avoid doing so on all Midgard and Bifrost GPUs.
+        // Valhall (eg Mali-Gx7 onwards) appears to be unnaffected. See bug 1691955, bug 1558374,
+        // and bug 1663355.
+        let supports_render_target_partial_update = !(renderer_name.starts_with("Mali-T")
+            || renderer_name == "Mali-G31"
+            || renderer_name == "Mali-G51"
+            || renderer_name == "Mali-G71"
+            || renderer_name == "Mali-G52"
+            || renderer_name == "Mali-G72"
+            || renderer_name == "Mali-G76");
 
         let supports_shader_storage_object = match gl.get_type() {
             // see https://www.g-truc.net/post-0734.html
@@ -1777,7 +1782,7 @@ impl Device {
         if is_software_webrender {
             // No benefit to batching texture uploads with swgl.
             requires_batched_texture_uploads = Some(false);
-        } else if is_mali_g {
+        } else if renderer_name.starts_with("Mali-G") {
             // On Mali-Gxx the driver really struggles with many small texture uploads,
             // and handles fewer, larger uploads better.
             requires_batched_texture_uploads = Some(true);
@@ -1786,7 +1791,7 @@ impl Device {
         // On Mali-Txxx devices we have observed crashes during draw calls when rendering
         // to an alpha target immediately after using glClear to clear regions of it.
         // Using a shader to clear the regions avoids the crash. See bug 1638593.
-        let supports_alpha_target_clears = !is_mali_t;
+        let supports_alpha_target_clears = !renderer_name.starts_with("Mali-T");
 
         // On Adreno 4xx devices with older drivers we have seen render tasks to alpha targets have
         // no effect unless the target is fully cleared prior to rendering. See bug 1714227.