On Sat, 17 Nov 2012, Lan Tianyu wrote: > Some usb devices can't be resumed correctly after power off. This > patch is to add pm qos flags request to change NO_POWER_OFF and > provide usb_device_allow_power_off() for device drivers to allow or > prohibit usb core to power off the device. What happens if there are two drivers bound to two different interfaces, and they both call usb_device_allow_power_off(false), and then one of the drivers is unbound and calls usb_device_allow_power_off(on)? Also, instead of using PM QOS flags for this, why not simply have usb_device_allow_power_off call pm_runtime_{get,put}_sync on the port device? 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