Why desktop doesn't work in 25.04 on s905w2 and s905x4

[bemmivend325]

First release of Ubuntu Plucky Puffin (25.04). BUT be warned, desktop does not work for S905W2 and S905X4. I haven't figured out why yet. It does not seems to be kernel related. So if someone figures it out, please let me know. (I have a vague suspicion it has something to do with triple buffering of Gnome 48?).
it's an AFBC issue
Mesa 25
https://docs.mesa3d.org/relnotes/25.0.0.html
panfrost: Add support for AFBC(split)
panfrost: Advertise support for AFBC(32x8,sparse,split)
etc

using environment variable PAN_MESA_DEBUG="noafbc" alleviates the issue. If the login screen doesn't appear for you, move your mouse around. To use the computer with the faulty mesa version without disabling AFBC, I had a window of glxgears open. I would use mesa 24 until it's fixed.

[bemmivend325]

Related links
https://gitlab.freedesktop.org/mesa/mesa/-/issues/12718
https://oftc.catirclogs.org/panfrost/2025-03-05#
https://community.mnt.re/t/display-flickering-on-pocket-reform-related-to-mesa-25-0-0/3133
The cause is the same but our issue is worse, the screen is in a constant state of flicker unless there is an update on the screen in which case we get a frame worth of output. This is why moving the mouse or having glxgears open helps (eglgears es2gears _wayland etc)

[devmfc]

What you see is exactly what I saw. Just keep moving the mouse and it works ;-). Quite a creative idea to use glxgears for this.
Thanks for these pointers! I will have a look into that when I have time.