linux-kernel - Re: [Regression] PCI / PM: Simplify device wakeup settings code

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Date:   Mon, 16 Apr 2018 17:58:10 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Joseph Salisbury <joseph.salisbury@...onical.com>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Linux PCI <linux-pci@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        1745646@...s.launchpad.net
Subject: Re: [Regression] PCI / PM: Simplify device wakeup settings code

On Mon, Apr 16, 2018 at 5:31 PM, Joseph Salisbury
<joseph.salisbury@...onical.com> wrote:
> On 04/13/2018 05:34 PM, Rafael J. Wysocki wrote:
>> On Fri, Apr 13, 2018 at 7:56 PM, Joseph Salisbury
>> <joseph.salisbury@...onical.com> wrote:
>>> Hi Rafael,
>>>
>>> A kernel bug report was opened against Ubuntu [0].  After a kernel
>>> bisect, it was found that reverting the following two commits resolved
>>> this bug:
>>>
>>> 0ce3fcaff929 ("PCI / PM: Restore PME Enable after config space restoration")
>>> 0847684cfc5f("PCI / PM: Simplify device wakeup settings code")
>>>
>>> This is a regression introduced in v4.13-rc1 and still exists in
>>> mainline.  The bug causes the battery to drain when the system is
>>> powered down and unplugged, which does not happed prior to these two
>>> commits.
>> What system and what do you mean by "powered down"?  How much time
>> does it take for the battery to drain now?
> By powered down, the bug reporter is saying physically powered off and
> unplugged.  The system is a HP laptop:
>
> dmi.chassis.vendor: HP
> dmi.product.family: 103C_5335KV HP Notebook
> dmi.product.name: HP Notebook
> vendor_id    : GenuineIntel
> cpu family    : 6
>
>
>>
>>> The bisect actually pointed to commit de3ef1e, but reverting
>>> these two commits fixes the issue.
>>>
>>> I was hoping to get your feedback, since you are the patch author.  Do
>>> you think gathering any additional data will help diagnose this issue,
>>> or would it be best to submit a revert request?
>> First, reverting these is not an option or you will break systems
>> relying on them now.  4.13 is three releases back at this point.
>>
>> Second, your issue appears to be related to the suspend/shutdown path
>> whereas commit 0ce3fcaff929 is mostly about resume, so presumably the
>> change in pci_enable_wake() causes the problem to happen.  Can you try
>> to revert this one alone and see if that helps?
> A test kernel with commits 0ce3fcaff929 and de3ef1eb1cd0 reverted was
> tested.  However, the test kernel still exhibited the bug.

So essentially the bisection result cannot be trusted.