linux-kernel - Re: [Bug 216877] New: Regression in PCI powermanagement breaks resume after suspend

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Message-ID: <fa187ea6-eaba-92cd-b2bc-a62d25501826@witt.link>
Date:   Wed, 4 Jan 2023 16:37:46 +0100
From:   Thomas Witt <kernel@...t.link>
To:     Bjorn Helgaas <helgaas@...nel.org>
Cc:     Vidya Sagar <vidyas@...dia.com>, linux-kernel@...r.kernel.org,
        linux-pci@...r.kernel.org
Subject: Re: [Bug 216877] New: Regression in PCI powermanagement breaks resume
 after suspend

On 04/01/2023 16:02, Bjorn Helgaas wrote:
> On Wed, Jan 04, 2023 at 09:44:25AM +0100, Thomas Witt wrote:
>> On 04/01/2023 01:30, Bjorn Helgaas wrote:
>>> On Mon, Jan 02, 2023 at 11:15:16AM -0600, Bjorn Helgaas wrote:
>>>> On Mon, Jan 02, 2023 at 02:02:51PM +0000, bugzilla-daemon@...nel.org wrote:
>>>>> https://bugzilla.kernel.org/show_bug.cgi?id=216877
>>>>>
>>>>>               Bug ID: 216877
>>>>>              Summary: Regression in PCI powermanagement breaks resume after
>>>>>                       suspend
>>>>>       Kernel Version: 6.0.0-rc1
> 
> BTW, if the bisect is correct, I think the regression actually is in
> v6.1-rc1, where 5e85eba6f50d ("PCI/ASPM: Refactor L1 PM Substates
> Control Register programming") appeared.
> 
>>>>> Created attachment 303512
>>>>>     --> https://bugzilla.kernel.org/attachment.cgi?id=303512&action=edit
>>>>> output of git bisect log
>>>>>
>>>>> After commit 5e85eba6f50dc288c22083a7e213152bcc4b8208 "PCI/ASPM:
>>>>> Refactor L1 PM Substates Control Register programming" my Laptop
>>>>> does not resume PCI devices back from suspend.
>>>
>>> Thomas, could you try the debug patch below on top of v6.2-rc1?
>>
>> Thank you for that patch Bjorn, but as far as I can see it does not change
>> anything.
> 
> Thanks for testing it.  Maybe Vidya will have more ideas.  The patch
> below (based on v6.2-rc1) would revert 5e85eba6f50d and 4ff116d0d5fd.
> If 5e85eba6f50d is the culprit, it should fix the regression.  It
> would also potentially break L1 substates after resume, so we'd like
> to avoid reverting it if possible.
> 
> But the "Unable to change power state from D3hot to D0, device
> inaccessible" symptom suggests that the device is still in D3, which
> would be more like a wakeup issue than an ASPM issue.
> 
> Your bisect log said 3e347969a577 ("PCI/PM: Reduce D3hot delay with
> usleep_range()") was "good", but it would be worth double-checking,
> e.g., see if reverting it from v6.2-rc1 makes any difference.
> 
> Bjorn
> 
> commit 61de2691d549 ("Revert "PCI/ASPM: Refactor L1 PM Substates Control Register programming"")
> parent 1b929c02afd3
> Author: Bjorn Helgaas <bhelgaas@...gle.com>
> Date:   Wed Jan 4 08:38:53 2023 -0600
> 
>      Revert "PCI/ASPM: Refactor L1 PM Substates Control Register programming"

With this patch on top of 6.2-rc1 suspend/resume works and my PCI 
devices come back online.