Power down USB when suspending

John Gilmore gnu at toad.com
Tue Oct 5 17:02:59 EDT 2010

It would be better if you could explain WHY you need to take a photo
quickly after resuming.  Is the idea that the laptop will save power?
It could remain suspended for a long time, wake and take a picture,
then suspend again until the next picture is needed.  In that case,
you can wake it a bit early, and it can still take the picture on
time.  If suspend in the OS was working properly, you could just
sleep() as long as you require, and the OS would automatically suspend
and resume at the right times.  (Though if you have a USB peripheral
plugged in, it shouldn't be suspending at all, since that cuts the power
to the peripheral, which might not be able to deal with that.)

Is there some other reason why you need the laptop to suspend?

(Even if it could power the USB bus during suspend -- or if you use
an external USB hub with power -- the camera will burn power constantly
rather than saving power while suspended.)

The built-in XO-1 camera is not connected via USB, so it should be
available more quickly after resuming from a suspend, if you can use it
instead of a USB webcam.


More information about the Devel mailing list