On Fri, 16 Jan 2015, vichy wrote: > hi alan: > > > > Firstly, you should realize that a hub port can be put into suspend > > _only_ if a device is plugged into it. If nothing is plugged into a > > port then the port cannot be put into suspend. > > > > Secondly, you should realize that putting a USB device into suspend > > means the same thing as suspending the hub port the device is plugged > > into. > > > > Thirdly, you should realize therefore that if _all_ the devices > > attached to the host controller are in runtime suspend, then all the > > connected ports must be suspended. (And none of the disconnected ports > > can be suspended, since it is impossible to suspend a disconnected > > port.) > Is 3rd situation you mentioned above the function will be called is > hcd->bus_suspend? hcd->bus_suspend will be called first, and shortly afterward ehci->suspend will be called (if this is an EHCI controller). > > Fourthly, you should realize that "controller itself will also be put > > into runtime suspend" means the controller itself will be put into > > runtime suspend. > is 4th situation you mentioned above the function will be called is > ehci_suspend, (take ehci for example)? Yes. > but ehci_supend is called when system is going to suspend/hibernate, > or it will be called even in runtime suspend? Both. > BTW, when I turn off the led on the keyboard, the keyboard can > successfully go to runtime suspend. Good. > Would you mind to let us know how you find out the problem from mon files? > Is it due there is no remote wake control message on the mon file? The usbmon trace showed that the interrupt URB for one of the HID interfaces was cancelled (indicating that the interface had been suspended) but the interrupt URB for the other HID interface was not cancelled (indicating that the interface had failed to suspend). Reading the source code for the usbhid driver showed that there are only a few reasons for failing to suspend an interface, and one of those reasons was if an LED was illuminated. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
