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Subject: Re: [Regression] PCI / PM: Simplify device wakeup settings code
To:     "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        Bjorn Helgaas <helgaas@kernel.org>
Cc:     Len Brown <lenb@kernel.org>, Bjorn Helgaas <bhelgaas@google.com>,
        ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
        Linux PCI <linux-pci@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        1745646@bugs.launchpad.net,
        Mika Westerberg <mika.westerberg@linux.intel.com>
References: <56a8953c-d833-837c-57d5-fe758d4db02a@canonical.com>
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From:   Joseph Salisbury <joseph.salisbury@canonical.com>
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Message-ID: <405049ce-5ea4-48b6-40da-4775daa94aea@canonical.com>
Date:   Mon, 7 May 2018 12:15:01 -0400
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On 05/04/2018 07:14 AM, Rafael J. Wysocki wrote:
> On Thursday, May 3, 2018 11:29:18 PM CEST Rafael J. Wysocki wrote:
>> On Thu, May 3, 2018 at 9:11 PM, Bjorn Helgaas <helgaas@kernel.org> wrote:
>>> On Thu, May 03, 2018 at 02:29:02PM -0400, Joseph Salisbury wrote:
>>>> On 05/02/2018 06:41 AM, Rafael J. Wysocki wrote:
>>>>> On Tue, May 1, 2018 at 9:55 PM, Bjorn Helgaas <helgaas@kernel.org> wrote:
>>>>>> On Tue, May 01, 2018 at 10:34:29AM +0200, Rafael J. Wysocki wrote:
>>>>>>> On Mon, Apr 30, 2018 at 4:22 PM, Joseph Salisbury
>>>>>>> <joseph.salisbury@canonical.com> wrote:
>>>>>>>> On 04/16/2018 11:58 AM, Rafael J. Wysocki wrote:
>>>>>>>>> On Mon, Apr 16, 2018 at 5:31 PM, Joseph Salisbury
>>>>>>>>> <joseph.salisbury@canonical.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@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.
>>>>>>>>> So essentially the bisection result cannot be trusted.
>>>>>>>> We performed some more testing and confirmed just a revert of the
>>>>>>>> following commit resolves the bug:
>>>>>>>>
>>>>>>>> 0847684cfc5f0 ("PCI / PM: Simplify device wakeup settings code")
>>>>>>> Thanks for confirming this!
>>>>>>>
>>>>>>>> Can you think of any suggestions to help debug further?
>>>>>>> The root cause of the regression is likely the change in
>>>>>>> pci_enable_wake() removing the device_may_wakeup() check from it.
>>>>>>>
>>>>>>> Probably, one of the drivers in the platform calls pci_enable_wake()
>>>>>>> directly from its ->shutdown() callback and that causes the device to
>>>>>>> be set up for system wakeup which in turn causes the power draw while
>>>>>>> the system is off to increase.
>>>>>>>
>>>>>>> I would look at the PCI drivers used on that platform to find which of
>>>>>>> them call pci_enable_wake() directly from ->shutdown() and I would
>>>>>>> make these calls conditional on device_may_wakeup().
>>>>>> I took a quick look with
>>>>>>
>>>>>>   git grep -E "pci_enable_wake\(.*[^0]\);|device_may_wakeup"
>>>>>>
>>>>>> and didn't notice any pci_enable_wake() callers that called
>>>>>> device_may_wakeup() first.
>>>>> I've just look at a bunch of network drivers doing that.
>>>>>
>>>>> It looks like I may need to restore __pci_enable_wake() with an extra
>>>>> "runtime" argument for internal use.
>>>>>
>>>>> Joseph, can you ask the reporter to test the Bjorn's patch, please?
>>>> The bug reporter has testing Bjorn's patch.  It did in fact resolve the
>>>> bug.  Thanks for the quick help, Rafael and Bjorn!
>>> Just as a word of caution, I think Rafael said my patch was not the
>>> right fix because it would break something else.  So I would wait for
>>> a better patch from Rafael before actually resolving this issue.
>> I'll do my best to provide one in the next couple of days.
> Something like the appended one (compiled-only at this point).
>
> Joseph, this should be functionally equivalent to the Bjorn's patch except
> for the runtime PM part which is irrelevant for the issue in question, but
> please ask the reported to test this one too.
>
> If it is confirmed to work, I'll repost it with a proper changelog.
The bug reporter confirms that your latest patch also resolves the bug. 
Thanks!

>
> ---
>  drivers/pci/pci.c |   31 ++++++++++++++++++++++++-------
>  1 file changed, 24 insertions(+), 7 deletions(-)
>
> Index: linux-pm/drivers/pci/pci.c
> ===================================================================
> --- linux-pm.orig/drivers/pci/pci.c
> +++ linux-pm/drivers/pci/pci.c
> @@ -1910,7 +1910,7 @@ void pci_pme_active(struct pci_dev *dev,
>  EXPORT_SYMBOL(pci_pme_active);
>  
>  /**
> - * pci_enable_wake - enable PCI device as wakeup event source
> + * __pci_enable_wake - enable PCI device as wakeup event source
>   * @dev: PCI device affected
>   * @state: PCI state from which device will issue wakeup events
>   * @enable: True to enable event generation; false to disable
> @@ -1928,7 +1928,7 @@ EXPORT_SYMBOL(pci_pme_active);
>   * Error code depending on the platform is returned if both the platform and
>   * the native mechanism fail to enable the generation of wake-up events
>   */
> -int pci_enable_wake(struct pci_dev *dev, pci_power_t state, bool enable)
> +static int __pci_enable_wake(struct pci_dev *dev, pci_power_t state, bool enable)
>  {
>  	int ret = 0;
>  
> @@ -1969,6 +1969,23 @@ int pci_enable_wake(struct pci_dev *dev,
>  
>  	return ret;
>  }
> +
> +/**
> + * pci_enable_wake - enable PCI device as wakeup event source
> + * @pci_dev: Target device
> + * @state: PCI state from which device will issue wakeup events
> + * @enable: Whether or not to enable event generation
> + *
> + * If @enable is set and device_may_wakeup() returns false for the device, it
> + * will not be enabled to generate wakeup events.
> + */
> +int pci_enable_wake(struct pci_dev *pci_dev, pci_power_t state, bool enable)
> +{
> +	if (enable && !device_may_wakeup(&pci_dev->dev))
> +		return -EINVAL;
> +
> +	return __pci_enable_wake(pci_dev, state, enable);
> +}
>  EXPORT_SYMBOL(pci_enable_wake);
>  
>  /**
> @@ -1981,9 +1998,9 @@ EXPORT_SYMBOL(pci_enable_wake);
>   * should not be called twice in a row to enable wake-up due to PCI PM vs ACPI
>   * ordering constraints.
>   *
> - * This function only returns error code if the device is not capable of
> - * generating PME# from both D3_hot and D3_cold, and the platform is unable to
> - * enable wake-up power for it.
> + * This function only returns error code if the device is not allowed to wake
> + * up the system from sleep or it is not capable of generating PME# from both
> + * D3_hot and D3_cold and the platform is unable to enable wake-up power for it.
>   */
>  int pci_wake_from_d3(struct pci_dev *dev, bool enable)
>  {
> @@ -2114,12 +2131,12 @@ int pci_finish_runtime_suspend(struct pc
>  
>  	dev->runtime_d3cold = target_state == PCI_D3cold;
>  
> -	pci_enable_wake(dev, target_state, pci_dev_run_wake(dev));
> +	__pci_enable_wake(dev, target_state, pci_dev_run_wake(dev));
>  
>  	error = pci_set_power_state(dev, target_state);
>  
>  	if (error) {
> -		pci_enable_wake(dev, target_state, false);
> +		__pci_enable_wake(dev, target_state, false);
>  		dev->runtime_d3cold = false;
>  	}
>  
>