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USB: Reset USB 3.0 devices on (re)discovery
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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>
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Luben Tuikov authored and Greg Kroah-Hartman committed Feb 17, 2011
1 parent 72a012c commit 637d11b
Showing 1 changed file with 7 additions and 11 deletions.
18 changes: 7 additions & 11 deletions drivers/usb/core/hub.c
Original file line number Diff line number Diff line change
Expand Up @@ -2681,17 +2681,13 @@ hub_port_init (struct usb_hub *hub, struct usb_device *udev, int port1,

mutex_lock(&usb_address0_mutex);

if (!udev->config && oldspeed == USB_SPEED_SUPER) {
/* Don't reset USB 3.0 devices during an initial setup */
usb_set_device_state(udev, USB_STATE_DEFAULT);
} else {
/* Reset the device; full speed may morph to high speed */
/* FIXME a USB 2.0 device may morph into SuperSpeed on reset. */
retval = hub_port_reset(hub, port1, udev, delay);
if (retval < 0) /* error or disconnect */
goto fail;
/* success, speed is known */
}
/* Reset the device; full speed may morph to high speed */
/* FIXME a USB 2.0 device may morph into SuperSpeed on reset. */
retval = hub_port_reset(hub, port1, udev, delay);
if (retval < 0) /* error or disconnect */
goto fail;
/* success, speed is known */

retval = -ENODEV;

if (oldspeed != USB_SPEED_UNKNOWN && oldspeed != udev->speed) {
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