Am Mittwoch, 16. Mai 2007 12:01 schrieb Robert Marquardt:
> >> A suspended bus-powered USB device cannot drive LEDs so suspending an
> >> USB keyboard with CAPS LOCK on means it gets out of sync.
> >
> > How much power does an LED need? You have 2mA in suspended mode.
>
> A standard LED uses about 20 mA and you have 3 of them for a keyboard.
> That is the reason why wireless keyboard do not have LEDs.
That's useful info.
> So in suspend the keyboard must switch off the LEDs which in turn means
> either keyboards cannot autosuspend at all or you have to allow that the
> LEDs obn the keyboard are sometimes not in sync with their state.
Yes. The same way a blanked screen is not in sync with X's view of
screen content.
> BTW is the keyboard not required restore the the LEDs on its own when
> resuming?
The keyboard's view of the status might be outdated.
Regards
Oliver
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