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 Stern
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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