Re: autosuspend for hid
Oliver Neukum <[email protected]>
| Newsgroups | gmane.linux.usb.devel |
|---|---|
| Organization | Novell |
| Message-ID | <[email protected]> |
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 The keyboard's view of the status might be outdated.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 ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ [email protected] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel