Re: [PATCH v2] Disable panel self-refresh on AMD GPUs

[Demi Marie Obenour <demiobenour@gmail.com>]

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On 5/21/26 11:50, Alyssa Ross wrote:
> Demi Marie Obenour <demiobenour@gmail.com> writes:
> 
>> On 5/21/26 08:52, Alyssa Ross wrote:
>>> Demi Marie Obenour <demiobenour@gmail.com> writes:
>>>
>>>> KDE Linux has already done this.  It works around a long-running bug in
>>>> the AMD GPU driver, which I believe also affects my test laptop.
>>>> Without the workaround, the system freezes and does not recover until a
>>>> hard reboot.
>>>
>>> You tested this on your test laptop and it solved the problem?
>>
>> I didn't test it on my own hardware.  After having spent so long on
>> Cloud Hypervisor, I'm having to set myself up for Spectrum development
>> again, and that is taking a little bit of time.
>>
>> However, the symptoms are identical to what many others have seen:
>> a freeze that needs a hard reboot to recover from.
>>
>>> Did you manually work around the card0/card1 bug?
>>
>> That bug would cause Weston to fail to start, but not to freeze
>> once started.
> 
> Right, but you'd have to get past it to even observe this problem,
> wouldn't you?  So I'm not sure anybody would actually be affected by
> this currently.

This patch could still be useful once Spectrum uses COSMIC, or for
anyone who has worked around the card0/card1 bug in their trees.
I'll see if it fixes the problem on my system.

If this does fix the problem on my system (with the workaround),
I recommend applying it.  Once KDE Linux stops including
amdgpu.dcdebugmask=0x10, it then makes sense for Spectrum to do
the same.

This problem is very severe and has lasted quite a while [1].

There is also a report [2] of corruption on certain systems that
needs amdgpu.dcdebugmask=0x410 to resolve.  There is a patch [3]
but it is not upstreamed to Linus's tree.  It might be fixed by
AMD moving the relevant functionality into the power module in the
display controller.  Presumably, this is firmware shared with Windows,
which means it should be better tested.

Given the long list of problems with the display controller driver [4],
I suspect it is better to use the workaround for now. 

[1]: https://invent.kde.org/kde-linux/kde-linux/-/merge_requests/431
[2]: https://gitlab.freedesktop.org/drm/amd/-/work_items/5087
[3]: https://lore.kernel.org/amd-gfx/20260329035830.21953-1-voroninan95ton@gmail.com/
[4]: https://gitlab.freedesktop.org/drm/amd/-/work_items?state=opened&label_name%5B%5D=DC
-- 
Sincerely,
Demi Marie Obenour (she/her/hers)

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