[Intel] Screen artifacts on transparent windows with picom
System information
System: Host: my-TUXEDO Kernel: 5.4.0-90-generic x86_64 bits: 64 gcc: 7.5.0 Desktop: i3 4.14.1 dm: gdm3
Distro: Ubuntu 18.04.6 LTS
CPU: Quad core Intel Core i7-8565U (-MT-MCP-) arch: Kaby Lake rev.12 cache: 8192 KB
flags: (lm nx sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx) bmips: 15999
clock speeds: min/max: 400/4600 MHz 1: 759 MHz 2: 751 MHz 3: 714 MHz 4: 781 MHz 5: 755 MHz 6: 753 MHz
7: 745 MHz 8: 742 MHz
Graphics: Card: Intel Device 3ea0 bus-ID: 00:02.0 chip-ID: 8086:3ea0
Display Server: x11 (X.Org 1.19.6 ) drivers: modesetting (unloaded: fbdev,vesa)
Resolution: 1920x1080@60.01hz, 1680x1050@59.88hz
OpenGL: renderer: Mesa DRI Intel UHD Graphics 620 (WHL GT2)
version: 4.6 Mesa 21.3.0 - kisak-mesa PPA (compat-v: 3.0) Direct Render: Yes
Issue description
I use the picom compositor on i3 window manager. When I have a transparent window without titlebar above (higher on the screen, on a vertical tiled mode) a window with titlebar, the transparent window shows artifacts in its background (instead of the wallpaper, for example). Especially when resizing the windows.
I've described this issue on picom's GitHub (see here). The maintainer thinks it's a driver issue, and asked me to report to mesa to have more info.
Regression
Occurs with 20.2.0 (latest release in Ubuntu 18.04 ppa) and with 21.3.0.
Log files
dmesg
does not yield anything of interest. Should I look elsewhere? (How exactly?)
Screenshot
Edited by Noé Cornet