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by Delk 704 days ago
I initially got somewhat frequent hangs on Fedora with a Radeon 680M iGPU (in a Ryzen 7 PRO 6850U APU). The hangs stopped when I added amdgpu.dcdebugmask=0x10 to kernel boot options, based on some comments in an AMD Linux driver bug report [1]. That seems to disable panel self-refresh so it would seem to be related to that somehow.

Stability has been fine since. The bug report has since been closed but I haven't tested in a while to see if disabling PSR is still needed or if the issue has actually been fixed.

I haven't seen significant stability issues on Windows, although I don't use it much on the AMD device.

[1] https://gitlab.freedesktop.org/drm/amd/-/issues/2443
2 comments
saltcured 704 days ago
Is that Wayland or Xorg?

With PSR in the mix, is the system really hanging or is it just failing to update the screen somehow? I.e. can you tell the difference with logs or a remote connection or configure and use an unprompted shutdown via the power button?

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Delk 699 days ago
It was on Wayland. I'm not sure if I tried with X.

I can't remember the details of it. It effectively hung in the sense that I couldn't get the system into a usable state again locally without rebooting. I'm not sure if the system responded to the power button or not, or whether there was useful log output.

I didn't bother trying with a remote connection since the hang was frequent enough that it wouldn't have been of any use as a workaround anyway. I'd guess switching to another virtual console probably didn't work because I'd probably remember it if it did.

I can try re-enabling PSR and see if the problem is still there if you're interested.

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Delk 696 days ago
Looks like some of the patches discussed in that bug report work around the problem by disabling PSR-SU for the specific timing controller my display also has. Those patches are in current kernels already. So basically the problem is gone for me, even if I remove the dcdebugmask.

So, I don't really know if the system was fully hanging, or if the display was just unable to update any more, but it was likely exactly the same that happened to other people with Parade TCONs in that bug discussion.

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Joel_Mckay 704 days ago
Thanks for contributing.

Your tip may help some folks in the future. =)

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