On Fri, Sep 21, 2012 at 08:21:01PM +0200, Peter Stuge wrote: > Sarah Sharp wrote: > > a userspace program claims the interface via usbfs and reads from > > the device when it wants to capture a finger scan. The kernel's > > "auto" power policy would turn back on the port as soon as the > > interface was claimed through usbfs. > > This translates to a slightly less appealing user experience where > users can't simply swipe finger to unlock a locked screen but must > first wake up the userspace process, or to smaller power savings, > if the port can never be powered off as long as the screen is locked. I think it would be the latter case. If userspace keeps the device open while the screen is locked, then we wouldn't power off the device. The desktop environment could be smart and release the finger print reader when the screen blanks. But then the screen wouldn't unblank when someone swiped their finger. They would have to hit a key or wiggle a mouse to unblank the screen, which would cause the userspace program to claim the interface. Then they could swipe their finger. So to ensure the best user experience, the locked screen would probably hold the device open all the time. I'll have to play around with my thinkpad fingerprint reader and see what modern desktop environments do with it. However, the majority of users who don't use a finger print reader will get better power savings. Sarah Sharp -- 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
