On Wed, Oct 23, 2013 at 10:55:08AM -0400, Alan Stern wrote: > On Tue, 22 Oct 2013, Peter Chen wrote: > > > Hi Alan, > > > > Currently, the controller's wakeup setting is enabled by default, > > is it ok let it be disabled by default, and let the user control it. > > Enable usb wakeup will cause more power consumption(some phy logic > > need to be on to detect wakeup) and unexpected usb wakeup may be > > considered as an unexpected behaviour. > > Isn't this the sort of thing that should be handled in userspace? If > the user (or the distro) sets the appropriate wakeup value for the > controller then the default doesn't matter. > > It's not possible for the kernel to guess what the user wants. For > example, if there's a USB keyboard then probably wakeup should be > enabled. But what if there's a mouse and no keyboard? The kernel > can't tell. In the end, we have to let the user tell us. > > > Meanwhile, the controller may not be dedicated for host, it may otg > > controller, the hcd is deleted when switches to device mode, > > the wakeup setting for controller is still enabled, it is not suitable. > > If the HC is deleted and the UDC is added then the wakeup settings > should be determined by the UDC, not by the HC. The next time the > system goes to sleep, the UDC driver should be responsible for enabling > or disabling wakeup. > I agree both of your points, but after thinking more, I doubt that why hcd (or udc) needs to control its parent wakeup setting? Why not let controller driver decide it? -- Best Regards, Peter Chen -- 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
