Sorry, my response on Davids mail was filtered by the list: I will prepare a patch based on Davids proposals and my experiences with the EHCI on the MPC8343 to change that. I will check whether my silicon would disable port power on its own as it would be supposed to do on OC, but if my memory doesn't trick me the current implementation re-enables power on all ports on all reported OC changes regardless whether the OC-situation begins or ends. USB spec says that the host would have to wait for the OC status bit to be cleared before cycling port power on. Maybe my problem comes from the fact that port power is re-enabled too quickly, not giving the controller the chance to get port power disabled properly, thus not running through its state machine as it would have to? (just thoughts...) - Christian
---------------------------------------------------------------------------- ---- Von: Alan Stern Gesendet: Sa 26.05.2007 17:48 An: David Brownell; Engelmayer Christian Cc: USB development list Betreff: Re: [linux-usb-devel] hub.c port power handling on over-current On Fri, 25 May 2007, David Brownell wrote: > I'd have to check, but I think that Linux won't currently turn > off per-port power unless the host controller reports that it > actually supports per-port power switching. And most EHCI > implementations don't report that in the hardware, so Linux > won't power it off ... In fact, Linux doesn't do very much in response to an overcurrent-change status. The hub driver clears the overcurrent-change feature and then tells the hub to enable power on all ports. It never tries to turn off port power, under any circumstances. Alan Stern ------------------------------------------------------------------------- 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/ _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
