Swiftshader on Ozone Wayland is completely unusable in Gnome (Debian 10)

[punishm...@gmail.com]

Not sure if it this is an unintended result of https://groups.google.com/a/chromium.org/g/chromium-dev/c/IzQX18GphxE/m/p-j3xAdbAQAJ , because this problem appears in all my builds after that patch was merged.

Simply put, the old patches in the link above solved the issue of using Chromium in Ozone Wayland mode on Swiftshader in Plasma 5.14.5 and Weston 5.0.0 in Debian 10. However, I noticed that since those patches were merged, none of my builds are usable on Gnome 3 because of severe flickering in which the contents of the browser's memory keep flickering onscreen. And it never occurred to me to test on Gnome 3 because I seldom use it.

Quick video samples of the issue under Gnome 3:

https://drive.google.com/file/d/1KSVZt3PEIe_LF9WqyuS5WuzprrWqLsUk/view?usp=sharing

https://drive.google.com/file/d/1KuvBTKjFwOMDPg78--nQqdvXocAjFv5P/view?usp=sharing

The flickering and cycling of content in memory gets even worse as more tabs are opened, but you get the picture.

This exists from Chromium v90 all the way to my most recent build on 24 Apr (Chromium 92), and affects official Google Chrome builds as well as Chromium-based browsers like Brave.

Not a developer, but I know my way around a few things. Please let me know what you need to investigate this bug and I will try to provide them.

Thanks!

[punishm...@gmail.com]

Additional information that may be useful:

Chromium was launched with the following params:

--enable-features=UseOzonePlatform,UseSkiaRenderer,WaylandOverlayDelegation,Vulkan --ozone-platform=wayland --disable-gpu-vsync --enable-gpu-rasterization --disable-gpu-driver-bug-workarounds --ignore-gpu-blocklist --use-gl=swiftshader  : Flickering happens in Gnome, no flickering in Plasma and Weston

--enable-features=UseOzonePlatform,UseSkiaRenderer,WaylandOverlayDelegation --ozone-platform=wayland --disable-gpu-vsync --enable-gpu-rasterization --disable-gpu-driver-bug-workarounds --ignore-gpu-blocklist --use-gl=swiftshader  : No flickering in Gnome, Plasma or Weston

--enable-features=UseOzonePlatform,UseSkiaRenderer,WaylandOverlayDelegation --ozone-platform=wayland --use-gl=swiftshader  : No flickering in Gnome, Plasma or Weston

--enable-features=UseOzonePlatform,UseSkiaRenderer,WaylandOverlayDelegation --ozone-platform=wayland --disable-gpu  : Flickering happens in Gnome, no flickering in Plasma and Weston

--enable-features=UseOzonePlatform,UseSkiaRenderer,WaylandOverlayDelegation,Vulkan --ozone-platform=wayland --disable-gpu  : Flickering happens in Gnome, no flickering in Plasma and Weston

Lastly, these results are on my laptop running on an Intel Atom E3950 with an Intel HD Graphics 505, Mesa 19., Kernel 5.1. Have not tested it in my workstations yet.

[punishm...@gmail.com]

Last bit of information:

Adding 'Vulkan' to --enable-features or using --disable-gpu forces Chrome to enter software compositing mode, and that is where the flickering issues start showing up under Gnome. 

[punishm...@gmail.com]

Additional information that may be useful:

Apparently, this issue existed well before the patches introduced in https://groups.google.com/a/chromium.org/g/chromium-dev/c/IzQX18GphxE/m/p-j3xAdbAQAJ 

Was testing some builds dating back in 2020 (v78) on my workstation in Debian 10 Gnome Wayland and the flickering is present as long as the browser is using software compositing, either by adding 'Vulkan' to --enable-features or using --disable-gpu

As mentioned earlier, the blinkings and flickerings do not show up under Plasma Wayland and Weston.

Hope this helps.

[Ken Russell]

Please file a bug on crbug.com containing this information; please spend the time to coalesce it down, and put all of your later corrections and followups into the initial bug report. Post the bug ID here once filed. Thanks.

-Ken

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[punishm...@gmail.com]

Bug 1204719 has been filed in crbug.com

Please help to look at it.

Thanks!