Comment 90 for bug 1745646

On Mon, Apr 16, 2018 at 5:31 PM, Joseph Salisbury
<email address hidden> wrote:
> On 04/13/2018 05:34 PM, Rafael J. Wysocki wrote:
>> On Fri, Apr 13, 2018 at 7:56 PM, Joseph Salisbury
>> <email address hidden> 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
> 103C_5335KV HP Notebook
> 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.