> It's not possible for the ports on your computer but it is possible > for certain brands of hub. For example, check out this page: > > http://www.gniibe.org/ac-power-by-usb/ac-power-control.html > > If you can get the right sort of hub, it just might work. Nice link! Thanks a lot! It seems like my hub (very cheap one: Ultron UH-430) supports it - not port by port but at least "Ganged power switching". First of all I made some tests with an optical USB mouse because it's easy to see whether it is powered or not (the dvb stick has no power indicators) Works fine. I'm able to turn it on and off. But unfortunately it does not work with the DVB stick.
Turning it off (uninitialized state) the first time produces no messages, turning power on leads to the well known: hub 1-5:1.0: state 7 ports 4 chg 0000 evt 0002 hub 1-5:1.0: port 1, status 0101, change 0001, 12 Mb/s hub 1-5:1.0: debounce: port 1: total 100ms stable 100ms status 0x101 usb 1-5.1: new high speed USB device using ehci_hcd and address 8 usb 1-5.1: khubd timed out on ep0in len=0/8 usb 1-5.1: device descriptor read/8, error -110 usb 1-5.1: khubd timed out on ep0in len=0/8 usb 1-5.1: device descriptor read/8, error -110 usb 1-5.1: new high speed USB device using ehci_hcd and address 9 usb 1-5.1: khubd timed out on ep0in len=0/8 usb 1-5.1: device descriptor read/8, error -110 usb 1-5.1: khubd timed out on ep0in len=0/8 usb 1-5.1: device descriptor read/8, error -110 usb 1-5.1: new high speed USB device using ehci_hcd and address 10 usb 1-5.1: khubd timed out on ep0in len=0/64 usb 1-5.1: khubd timed out on ep0in len=0/64 usb 1-5.1: khubd timed out on ep0in len=0/64 usb 1-5.1: device descriptor read/64, error -110 usb 1-5.1: khubd timed out on ep0in len=0/64 turning power off from now on produces: usb 1-5.1: device reset changed speed! hub 1-5:1.0: state 7 ports 4 chg 0000 evt 0002 from now on it is always the same. Disabling the stick in initilized state and then re-enabling it leads to a correct detection in WARM state - if the device would have been completely powered down I'd exected a detection in cold state. Anyway - it was a very interesting afternoon - I learned a lot :) - seems like I have to face the fact that the DVB stick is unusable in this maschine without replugging it. Olaf ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ Linux-usb-users@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-users
