tree 29b7fa9e237784e0c301e88ff83c5ba4935167a6
parent 72a012ce0a02c6c616676a24b40ff81d1aaeafda
author Luben Tuikov <ltuikov@yahoo.com> 1297452790 -0800
committer Greg Kroah-Hartman <gregkh@suse.de> 1297967424 -0800

USB: Reset USB 3.0 devices on (re)discovery

If the device isn't reset, the XHCI HCD sends
SET ADDRESS to address 0 while the device is
already in Addressed state, and the request is
dropped on the floor as it is addressed to the
default address. This sequence of events, which this
patch fixes looks like this:

usb_reset_and_verify_device()
	hub_port_init()
		hub_set_address()
			SET_ADDRESS to 0 with 1
		usb_get_device_descriptor(udev, 8)
		usb_get_device_descriptor(udev, 18)
	descriptors_changed() --> goto re_enumerate:
		hub_port_logical_disconnect()
			kick_khubd()

And then:

hub_events()
	hub_port_connect_change()
		usb_disconnect()
			usb_disable_device()
		new device struct
		sets device state to Powered
		choose_address()
		hub_port_init() <-- no reset, but SET ADDRESS to 0 with 1, timeout!

The solution is to always reset the device in
hub_port_init() to put it in a known state.

Signed-off-by: Luben Tuikov <ltuikov@yahoo.com>
Cc: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>