On Sat, Jul 04, 2020 at 09:22:45AM +0000, Peter Chen wrote: > On 20-07-03 10:19:11, Alan Stern wrote: > > On Fri, Jul 03, 2020 at 02:25:32PM +0800, Peter Chen wrote: > > > After that, the user could enable controller as wakeup source > > > for system suspend through /sys entry. > > > > > > Signed-off-by: Peter Chen <peter.chen@xxxxxxx> > > > --- > > > drivers/usb/host/xhci-plat.c | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c > > > index cebe24ec80a5..bb5d73f0a796 100644 > > > --- a/drivers/usb/host/xhci-plat.c > > > +++ b/drivers/usb/host/xhci-plat.c > > > @@ -287,7 +287,7 @@ static int xhci_plat_probe(struct platform_device *pdev) > > > *priv = *priv_match; > > > } > > > > > > - device_wakeup_enable(hcd->self.controller); > > > + device_set_wakeup_capable(hcd->self.controller, true); > > > > > > In fact both this patch and the original code are wrong. It really should > > be: > > > > device_init_wakeup(hcd->self.controller, true); > > > > This will add the wakeup entry in sysfs and set it to Enabled. This is > > the appropriate behavior, as explained in the kerneldoc for > > device_init_wakeup(). The reason is because the controller device doesn't > > create any wakeup events on its own; it merely relays wakeup requests from > > descendant devices (root hubs or USB devices). > > Hi Alan, > > At xhci-plat.c's system suspend API xhci_plat_suspend, it depends on > power/wakeup value to determine whether the controller should enable > port wakeup capabilities, and from the system level, whether the system > supports USB wakeup or not is better to be determined by user, and is > disabled by default. > > Yes, you are right. The wakeup events are from controller's descendant > devices, and it is better to use roothub's wakeup capability to control > portsc's wakeup setting. At controller driver, the meaning for wakeup > setting is enabling wakeup interrupt for hardware signal events (dp/dm for USB2, > and RX-detect for USB3), this hardware logic is the glue layer and > designed by each vendors, without this logic, the USB controller can't > be woken up due to the USBCMD.RS bit is cleared, and there is no > standard EHCI or xHCI interrupt. The controller's wakeup setting is > better to be disabled by default, and decided by user too. > > For me, either this patch or use roothub's wakeup capability to > control portsc wakeup setting, both are OK. Mathias, what's your > opinion? Mathias is starting a long vacation, so he might not reply for a while. Note that hcd-pci.c, ohci-platform.c, and ehci-platform.c all call device_wakeup_enable(). This indicates that xhci-plat.c should do the same -- presumably device_set_wakeup_capable() is already called somewhere in the platform-specific code. There is a brief discussion about this in Documentation/driver-api/pm/devices.rst. Alan Stern
