On Fri, Oct 26, 2012 at 5:18 AM, Rafael J. Wysocki <rjw@xxxxxxx> wrote:
> On Friday, October 26, 2012 01:07:51 PM Huang Ying wrote:
>> There are comments on why PME poll support is necessary for PCI
>> devices, but not for PCIe devices. That may lead to misunderstanding
>> that PME poll is only necessary for PCI devices. So add comments
>> related to PCIe PME poll to make it more clear.
>>
>> The content of comments comes from the changelog of commit:
>>
>> 379021d5c0899fcf9410cae4ca7a59a5a94ca769
>>
>> Cc: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
>> Signed-off-by: Huang Ying <ying.huang@xxxxxxxxx>
>
> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
I applied this to my pci/misc branch as v3.8 material. Thanks!
>> ---
>> drivers/pci/pci.c | 28 +++++++++++++++++++---------
>> 1 file changed, 19 insertions(+), 9 deletions(-)
>>
>> --- a/drivers/pci/pci.c
>> +++ b/drivers/pci/pci.c
>> @@ -1578,15 +1578,25 @@ void pci_pme_active(struct pci_dev *dev,
>>
>> pci_write_config_word(dev, dev->pm_cap + PCI_PM_CTRL, pmcsr);
>>
>> - /* PCI (as opposed to PCIe) PME requires that the device have
>> - its PME# line hooked up correctly. Not all hardware vendors
>> - do this, so the PME never gets delivered and the device
>> - remains asleep. The easiest way around this is to
>> - periodically walk the list of suspended devices and check
>> - whether any have their PME flag set. The assumption is that
>> - we'll wake up often enough anyway that this won't be a huge
>> - hit, and the power savings from the devices will still be a
>> - win. */
>> + /*
>> + * PCI (as opposed to PCIe) PME requires that the device have
>> + * its PME# line hooked up correctly. Not all hardware vendors
>> + * do this, so the PME never gets delivered and the device
>> + * remains asleep. The easiest way around this is to
>> + * periodically walk the list of suspended devices and check
>> + * whether any have their PME flag set. The assumption is that
>> + * we'll wake up often enough anyway that this won't be a huge
>> + * hit, and the power savings from the devices will still be a
>> + * win.
>> + *
>> + * Although PCIe uses in-band PME message instead of PME# line
>> + * to report PME, PME does not work for some PCIe devices in
>> + * reality. For example, there are devices that set their PME
>> + * status bits, but don't really bother to send a PME message;
>> + * there are PCI Express Root Ports that don't bother to
>> + * trigger interrupts when they receive PME messages from the
>> + * devices below. So PME poll is used for PCIe devices too.
>> + */
>>
>> if (dev->pme_poll) {
>> struct pci_pme_device *pme_dev;
>>
> --
> I speak only for myself.
> Rafael J. Wysocki, Intel Open Source Technology Center.
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