On Fri, 14 Mar 2014, Dan Williams wrote: > 8<------- > Subject: usb: block suspension of superspeed port while hispeed peer is active > > From: Dan Williams <dan.j.williams@xxxxxxxxx> > > ClearPortFeature(PORT_POWER) on a usb3 port places the port in either a > DSPORT.Powered-off-detect / DSPORT.Powered-off-reset loop, or the > DSPORT.Powered-off state. There is no way to ensure that RX > terminations will persist in this state, so it is possible a device will > degrade to its usb2 connection. Prevent this by blocking power-off of a > usb3 port while its usb2 peer is active, and powering on a usb3 port > before its usb2 peer. > > By default the latency between peer power-on events is 0. In order for > the device to not see usb2 active while usb3 is still powering up inject > the hub recommended power_on_good delay. > > Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx> Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
