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

[Joseph Salisbury <joseph.salisbury@canonical.com>]

On 04/13/2018 05:34 PM, Rafael J. Wysocki wrote:
> On Fri, Apr 13, 2018 at 7:56 PM, Joseph Salisbury
> <joseph.salisbury@canonical.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.