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Message-ID: <9f0f9de4-2d34-4ff3-a901-c3e4b48e4ab0@5challer.de>
Date: Wed, 10 Jan 2024 13:39:56 +0100
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Subject: Re: [Regression] [PCI/ASPM] [ASUS PN51] Reboot on resume attempt
 (bisect done; commit found)
To: Kai-Heng Feng <kai.heng.feng@canonical.com>,
 Bjorn Helgaas <helgaas@kernel.org>
Cc: bhelgaas@google.com, linux-pci@vger.kernel.org,
 linux-kernel@vger.kernel.org, regressions@lists.linux.dev,
 macro@orcam.me.uk, ajayagarwal@google.com,
 sathyanarayanan.kuppuswamy@linux.intel.com, gregkh@linuxfoundation.org,
 hkallweit1@gmail.com, michael.a.bottini@linux.intel.com,
 johan+linaro@kernel.org
References: <954f0b86-dd9e-4d84-8d67-fba7e80bc94e@5challer.de>
 <20240105155100.GA1861423@bhelgaas>
 <CAAd53p5Eg4J9bRtAHY+JZ11cy1D0TnKmAaLfzcRJzw15VRBxXw@mail.gmail.com>
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From: Michael Schaller <michael@5challer.de>
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On 10.01.24 04:43, Kai-Heng Feng wrote:
> On Fri, Jan 5, 2024 at 11:51 PM Bjorn Helgaas <helgaas@kernel.org> wrote:
>>
>> On Fri, Jan 05, 2024 at 12:18:32PM +0100, Michael Schaller wrote:
>>> On 05.01.24 04:25, Kai-Heng Feng wrote:
>>>> Just wondering, does `echo 0 > /sys/power/pm_asysnc` help?
>>>
>>> Yes, `echo 0 | sudo tee /sys/power/pm_async` does indeed also result in a
>>> working resume. I've tested this on kernel 6.6.9 (which still has commit
>>> 08d0cc5f3426). I've also attached the relevant dmesg output of the
>>> suspend/resume cycle in case this helps.
>>
>> Thanks for testing that!
>>
>>> Furthermore does this mean that commit 08d0cc5f3426 isn't at fault but
>>> rather that we are dealing with a timing issue?
>>
>> PCI does have a few software timing requirements, mostly related to
>> reset and power state (D0/D3cold).  ASPM has some timing parameters,
>> too, but I think they're all requirements on the hardware, not on
>> software.
>>
>> Adding an arbitrary delay anywhere shouldn't break anything, and other
>> than those few required situations, it shouldn't fix anything either.
> 
> At least it means 8d0cc5f3426 isn't the culprit?
> 
> Michael, does the issue happen when iwlwifi module is not loaded? It
> can be related to iwlwifi firmware.
> 
> Kai-Heng
>
The issue still happens if the iwlwifi module has been blacklisted and 
after a reboot. This was again with vanilla kernel 6.6.9 and I've 
confirmed via dmesg that iwlwifi wasn't loaded.

I've also checked if there is a newer firmware but Ubuntu 23.10 is 
already using the newest firmware available from 
https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git/log/iwlwifi-8265-36.ucode 
(version 36.ca7b901d.0 according to dmesg).

Michael

>>
>> Bjorn