Re: Regression: mt7921e unable to change power state from d3cold to d0 - 6.12.x broken, past LTS 6.6.x works

[Sergio Callegari <sergio.callegari@gmail.com>]

Hi Christian,

Thanks for your nice offer, details below:

On 20/03/2025 11:05, Christian Heusel wrote:
> Hey Sergio,
> 
> On 25/03/20 08:49AM, Sergio Callegari wrote:
>> Might be able to test on the distro built kernels that basically trace the
>> releases and stable point releases. This should start helping bracketing the
>> problem a bit better as a starter. But it is going to take a lot of time,
>> since the issue happens when the machine fails to get out of hibernation,
>> that is not always, and obvioulsy I need to try avoiding this situation as
>> much as possible.
> 
> Which linux distro are you using? If you're on Arch Linux I can provide
> you with prebuilt images for the bisection :)

I am on manjaro, where the kernel follows slightly different naming 
conventions, but the arch kernels should be OK. So thank you very much 
for the nice offer. The thing is possibly a bit premature, in that I 
would like to identify first what is the kernel RC or point release 
where the issue started to appear, because I have these kernels 
available for my distro which makes things easier. Unfortunately, I am 
still in the dark even wrt this.

The issue is nasty, because it only happens when you crash on restore 
from hibernation, which is something that I am desperately trying to 
avoid because this is my work machine and I really don't want to risk 
data loss.

The big problem with this bug is that you remain with the impression 
that your hardware is bricked. On the web I read that booting windows 
immediately gives you back the wifi device on pcie, but I really cannot 
say, as I have no windows to try. What I can say is that the 6.6 LTS 
kernel also lets you recover the WIFI, while 6.12 LTS does not.

As a stopgap, would be great to know if there is anything that can be 
done while on 6.12 to fully reset the pcie (or the pcie device, I still 
don't know what is the culprit), so you don't need to boot an older kernel.

Thanks again,
Sergio

> 
>>
>> Incidentally, the machine seems to hibernate-resume just fine. It is when I
>> suspend-then-hibernate that I get the failures.
>>
>> Before contacting the network driver authors, I just wanted to query whether
>> the issue is likely in it or in the power-management or pcie subsystems.
>>
>> Thanks,
>> Sergio
> 
> Cheers,
> Chris
> 
>>
>> On 20/03/2025 00:54, Greg KH wrote:
>>> On Wed, Mar 19, 2025 at 08:38:52PM +0100, Sergio Callegari wrote:
>>>> There is a nasty regression wrt mt7921e in the last LTS series (6.12). If
>>>> your computer crashes or fails to get out of hibernation, then at the next
>>>> boot the mt7921e wifi does not work, with dmesg reporting that it is unable
>>>> to change power state from d3cold to d0.
>>>>
>>>> The issue is nasty, because rebooting won't help.
>>>
>>> Can you do a 'git bisect' to track down the issue?  Also, maybe letting
>>> the network driver authors know about this would be good.
>>>
>>> thanks,
>>>
>>> greg k-h
>>
>>