On Tue, Oct 11, 2016 at 11:18:28AM -0400, Alan Stern wrote:
> On Sat, 8 Oct 2016, Lukas Wunner wrote:
> > The PCI core already calls pm_runtime_get_sync() before invoking the
> > ->probe hook of a driver (see local_pci_probe()). Drivers need to
> > explicitly release a runtime ref to allow their device to suspend.
> > For xhci-pci, this seems to happen in usb_hcd_pci_probe():
> >
> > if (pci_dev_run_wake(dev))
> > pm_runtime_put_noidle(&dev->dev);
> >
> > So you could either modify the if-condition if you want to change the
> > behaviour for XHCI devices only, or if you want to change it in general,
> > add something like this to pci_dev_run_wake():
> >
> > /* PME capable in principle, but not from the intended sleep state */
> > if (dev->pme_support && !pci_pme_capable(dev, pci_target_state(dev)))
> > return false;
> >
> > I've briefly looked over the callers of pci_dev_run_wake() and the above
> > seems safe but you should double-check them.
>
> That seems like a good suggestion. The patch is below; Pierre, can you
> test it? This should remove the need to set the USB autosuspend module
> parameter to -1.
Alan, how do we proceed with this? Are you going to submit a patch
(with commit message, tags and all) to linux-pci@ or would you prefer
me to do that? I just went over the callers of pci_dev_run_wake()
once more and the patch still looks safe to me.
Thanks,
Lukas
>
> Index: usb-4.x/drivers/pci/pci.c
> ===================================================================
> --- usb-4.x.orig/drivers/pci/pci.c
> +++ usb-4.x/drivers/pci/pci.c
> @@ -2064,6 +2064,10 @@ bool pci_dev_run_wake(struct pci_dev *de
> if (!dev->pme_support)
> return false;
>
> + /* PME-capable in principle, but not from the intended sleep state */
> + if (!pci_pme_capable(dev, pci_target_state(dev)))
> + return false;
> +
> while (bus->parent) {
> struct pci_dev *bridge = bus->self;
>
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