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

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Date:   Thu, 26 Jan 2023 20:24:23 +0100
From:   Thomas Witt <thomas@...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 16:37, Thomas Witt wrote:
> On 04/01/2023 16:02, Bjorn Helgaas wrote:
>> 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.
> 

Hello Bjorn, hello Vidya,

do you have an Idea what went wrong in that commit to cause my PCI 
devices to not return from D3?

BR
Thomas