On Tuesday 17 July 2012 21:35:00 Lan Tianyu wrote: > On 2012/7/16 22:13, Alan Stern wrote: > > On Mon, 16 Jul 2012, Lan Tianyu wrote: > > > >> Currently, "power/wakeup" sysfs file can't control remote wakeup in the runtime > >> suspend. It only depends on "usb_interface->needs_remote_wakeup" to determine > >> whether enable remote wakeup or not when runtime suspending. Usr space has no > >> choice. This patch is to enable "power/wakeup" to control remote wakeup in the > >> runtime suspend. > > > > As Oliver pointed out, you need to explain why this is needed. > Yeah. Lost some background introduction. I recently try to realize usb > port power off mechanism for ports with device. So design, the port with > device only can be power off when remote wakeup disable. But I found > remote wakeup was entirely control by driver and userspace has no > control. needs_remote_wakeup is set to 1 when the device is opened. But the driver will not work if you don't use remote wakeup when it needs it. Under those circumstances you better unbind the driver. > So that means the device's remote wakeup can not be disabled and usb > port can not be powered off. So I try to provide a control of remote > wakeup to userspace. When system becomes idle such as blank screen, > some usb devices may be able to disable remote wakeup and power off. Yes, this is an unsoved problem. But the approach is no good. Don't disable remote wakeup behind the driver's back. Tell the driver that a reduced level of service is acceptable. Regards Oliver -- 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
