Rafael J. Wysocki wrote:
> On Monday, February 04, 2013 03:56:12 PM Konstantin Khlebnikov wrote:
>> Documentation/power/pci.txt says:
>> | It is expected that the device driver's pm->runtime_suspend() callback will
>> | not attempt to prepare the device for signaling wakeup or to put it into a
>> | low-power state.  The driver ought to leave these tasks to the PCI 
>> subsystem
>> | that has all of the information necessary to perform them.
>>
>> After commit 42eca2302146fed51335b95128e949ee6f54478f
>> ("PCI: Don't touch card regs after runtime suspend D3")
>> | If the driver takes care of state saving, don't touch any registers on it.
>> pci_pm_runtime_suspend() thinks if state has been saved by 
>> ->runtime_suspend()
>> that means device alredy prepared for wakeup and probably no longer 
>> accessible.
>>
>> Thus driver must either do all actions or leave all these tasks to PCI 
>> subsystem.
>
> I don't like this one, because it will generate noise for drivers that
> legitimately use pci_save_state() in their runtime suspend callbacks
> and know what they are doing.

Ok, you're right. Both these warnings can be false-positive.
For example some of wifi cards easily might be weird enough for this.

>
> Thanks,
> Rafael
>
>
>> Signed-off-by: Konstantin Khlebnikov<khlebni...@openvz.org>
>> Cc: Rafael J. Wysocki<rafael.j.wyso...@intel.com>
>> Cc: Bjorn Helgaas<bhelg...@google.com>
>> Cc: linux-...@vger.kernel.org
>> ---
>>   drivers/pci/pci-driver.c |   15 +++++++++++----
>>   1 file changed, 11 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
>> index f9aa311..2b0ff9a 100644
>> --- a/drivers/pci/pci-driver.c
>> +++ b/drivers/pci/pci-driver.c
>> @@ -1009,12 +1009,19 @@ static int pci_pm_runtime_suspend(struct device *dev)
>>              return 0;
>>      }
>>
>> -    if (!pci_dev->state_saved) {
>> -            pci_save_state(pci_dev);
>> -            pci_finish_runtime_suspend(pci_dev);
>> +    if (pci_dev->state_saved) {
>> +            WARN_ONCE(pci_dev->current_state == prev,
>> +                    "PCI PM: Power state of device not changed by %pF\n",
>> +                    pm->runtime_suspend);
>> +            WARN_ONCE(pci_dev_run_wake(pci_dev)&&
>> +                            !pci_dev->wakeup_prepared,
>> +                    "PCI PM: Waking of device not configured by %pF\n",
>> +                    pm->runtime_suspend);
>> +            return 0;
>>      }
>>
>> -    return 0;
>> +    pci_save_state(pci_dev);
>> +    return pci_finish_runtime_suspend(pci_dev);
>>   }
>>
>>   static int pci_pm_runtime_resume(struct device *dev)
>>
>> --
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>> More majordomo info at  http://vger.kernel.org/majordomo-info.html


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