iris: Scanout buffers now mapped WB cause glitches on screen
System information
Please post inxi -GSC -xx
output (fenced with triple backticks) OR fill information below manually
- OS: Debian
- GPU: 00:02.0 VGA compatible controller [0300]: Intel Corporation TigerLake-LP GT2 [Iris Xe Graphics] [8086:9a49] (rev 01)
- Kernel version: Linux koto 5.13.1 #6 (closed) SMP Sat Jul 10 15:51:05 PDT 2021 x86_64 GNU/Linux
- Mesa version: Mesa 21.3.0-devel (git-a82d012796)
- Xserver version (if applicable): 1.21.0.99
- Desktop manager and compositor: xfce, compositor disabled
Describe the issue
With compositing disabled, glamor rendering to the front buffer doesn't get flushed to memory causing random stale cache lines to be visible on the screen.
Regression
Regression caused by:
6e55890b: iris: Delete unused bo->cache_coherent flag
This patch removed code which switched scanout buffers to WC:
@@ -1338,7 +1335,6 @@ iris_bo_mark_exported_locked(struct iris_bo *bo)
* display HW. So make sure our CPU mappings don't assume cache
* coherency since display is outside that cache.
*/
- bo->cache_coherent = false;
bo->exported = true;
bo->reusable = false;
}
Any extra information would be greatly appreciated
Fixed by !12259 (merged)