linux-kernel - Re: linux-6.2-rc4+ hangs on poweroff/reboot: Bisected

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Date:   Mon, 30 Jan 2023 23:09:08 +0000
From:   Chris Clayton <chris2553@...glemail.com>
To:     Ben Skeggs <skeggsb@...il.com>
Cc:     Linux regressions mailing list <regressions@...ts.linux.dev>,
        bskeggs@...hat.com, Karol Herbst <kherbst@...hat.com>,
        Lyude Paul <lyude@...hat.com>,
        ML nouveau <nouveau@...ts.freedesktop.org>,
        LKML <linux-kernel@...r.kernel.org>,
        ML dri-devel <dri-devel@...ts.freedesktop.org>
Subject: Re: linux-6.2-rc4+ hangs on poweroff/reboot: Bisected

Hi again.

On 30/01/2023 20:19, Chris Clayton wrote:
> Thanks, Ben.

<snip>

>> Hey,
>>
>> This is a complete shot-in-the-dark, as I don't see this behaviour on
>> *any* of my boards.  Could you try the attached patch please?
> 
> Unfortunately, the patch made no difference.
> 
> I've been looking at how the graphics on my laptop is set up, and have a bit of a worry about whether the firmware might
> be playing a part in this problem. In order to offload video decoding to the NVidia TU117 GPU, it seems the scrubber
> firmware must be available, but as far as I know,that has not been released by NVidia. To get it to work, I followed
> what ubuntu have done and the scrubber in /lib/firmware/nvidia/tu117/nvdec/ is a symlink to
> ../../tu116/nvdev/scrubber.bin. That, of course, means that some of the firmware loaded is for a different card is being
> loaded. I note that processing related to firmware is being changed in the patch. Might my set up be at the root of my
> problem?
> 
> I'll have a fiddle an see what I can work out.
> 
> Chris
> 
>>
>> Thanks,
>> Ben.
>>
>>>

Well, my fiddling has got my system rebooting and shutting down successfully again. I found that if I delete the symlink
to the scrubber firmware, reboot and shutdown work again. There are however, a number of other files in the tu117
firmware directory tree that that are symlinks to actual files in its tu116 counterpart. So I deleted all of those too.
Unfortunately, the absence of one or more of those symlinks causes Xorg to fail to start. I've reinstated all the links
except scrubber and I now have a system that works as it did until I tried to run a kernel that includes the bad commit
I identified in my bisection. That includes offloading video decoding to the NVidia card, so what ever I read that said
the scrubber firmware was needed seems to have been wrong. I get a new message that (nouveau 0000:01:00.0: fb: VPR
locked, but no scrubber binary!), but, hey, we can't have everything.

If you still want to get to the bottom of this, let me know what you need me to provide and I'll do my best. I suspect
you might want to because there will a n awful lot of Ubuntu-based systems out there with that scrubber.bin symlink in
place. On the other hand,m it could but quite a while before ubuntu are deploying 6.2 or later kernels.

Thanks,

Chris

<snip>