On Wed, May 22, 2019 at 11:46:25PM +0800, Kai Heng Feng wrote: > > On May 22, 2019, at 9:48 PM, Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote: > > On Wed, May 22, 2019 at 11:42:14AM +0800, Kai Heng Feng wrote: > >> at 6:23 AM, Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote: > >>> On Wed, May 22, 2019 at 12:31:04AM +0800, Kai-Heng Feng wrote: > >>>> There's an xHC device that doesn't wake when a USB device gets plugged > >>>> to its USB port. The driver's own runtime suspend callback was called, > >>>> PME signaling was enabled, but it stays at PCI D0. > > ... > > And I guess this patch basically means we wouldn't call the driver's > > suspend callback if we're merely going to stay at D0, so the driver > > would have no idea anything happened. That might match > > Documentation/power/pci.txt better, because it suggests that the > > suspend callback is related to putting a device in a low-power state, > > and D0 is not a low-power state. > > Yes, the patch is to let the device stay at D0 and don’t run driver’s own > runtime suspend routine. > > I guess I’ll just proceed to send a V2 with updated commit message? Now that I understand what "runtime suspended to D0" means, help me understand what's actually wrong. The PCI core apparently *does* enable PME when we "suspend to D0". But somehow calling the xHCI runtime suspend callback makes the driver unable to notice when the PME is signaled? Bjorn
