Comment 6 for bug 2056445

>> Should this fix the flickering issue? I'm happy to test it out.
>
> It will fix a colored flickering;

My flickering has mostly actually usually been white - not colored (though
I was seeing the colored flickering lots before I switched off of Wayland,
which crashed too often with multiple monitors to be usable).

I see that the kernel is available in -proposed via rmadison, but I'm
struggling to install it. I added the -proposed pocket for main to my
/etc/apt/sources.list and updated my cache, but an `apt upgrade` didn't try
to upgrade to the new kernel. Am I missing something to get the proposed
kernel?

> but not the white screen (if that is
> what you're observing). It also fixes issues with suspend/resume that
> were present in earlier 6.8-rc kernels but fixed by the final version.

I've seen the white screen and suspend/resume issues as well.

>> I'm curious about the implications of the two workarounds presented. I
see that UMA_Game_Optimized will reserve some system ram for the GPU,
which I don't have any issues with if there is some benefit. Will this
use scatter/gather and therefore perform better as a result?
>
> If you use the BIOS option yes it will carve out more memory for VRAM
use. S/G is still used, but GTT memory is less likely to be accessed
when you have more VRAM. If you turn off S/G then GTT will NEVER be
used.

It sounds like GTT access is what causes this issue, and that using the
bios option won't guarantee that it will never happen. Is that correct?

> The potential negative implication for the BIOS option is more RAM being
used for GPU that can't be for anything else.
> The potential negative implications of turning off S/G in the driver are
that the driver may run out of memory in some situations that require a lot
of VRAM such as multiple 4k monitor docking.

Good to know, thanks for the details!

> FWIW - I have a FW13 AMD and I've never seen this white screen problem
myself. I don't know if it is tied to RAM vendor, RAM size, or a BIOS
issue. My educated guess is it's actually a BIOS issue and it might be
properly fixed when FW upgrades to the next BIOS.

Interesting. If there's any extra info (or testing) I can provide to help
with debugging/fixing this issue, please let me know.