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Commit 3cd12f91 authored by Dan Williams's avatar Dan Williams Committed by Greg Kroah-Hartman
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usb: force warm reset to break link re-connect livelock 



Resuming a powered down port sometimes results in the port state being
stuck in the training sequence.

 hub 3-0:1.0: debounce: port 1: total 2000ms stable 0ms status 0x2e0
 port1: can't get reconnection after setting port  power on, status -110
 hub 3-0:1.0: port 1 status 0000.02e0 after resume, -19
 usb 3-1: can't resume, status -19
 hub 3-0:1.0: logical disconnect on port 1

In the case above we wait for the port re-connect timeout of 2 seconds
and observe that the port status is USB_SS_PORT_LS_POLLING (although it
is likely toggling between this state and USB_SS_PORT_LS_RX_DETECT).
This is indicative of a case where the device is failing to progress the
link training state machine.

It is resolved by issuing a warm reset to get the hub and device link
state machines back in sync.

 hub 3-0:1.0: debounce: port 1: total 2000ms stable 0ms status 0x2e0
 usb usb3: port1 usb_port_runtime_resume requires warm reset
 hub 3-0:1.0: port 1 not warm reset yet, waiting 50ms
 usb 3-1: reset SuperSpeed USB device number 2 using xhci_hcd

After a reconnect timeout when we expect the device to be present, force
a warm reset of the device.  Note that we can not simply look at the
link status to determine if a warm reset is required as any of the
training states USB_SS_PORT_LS_POLLING, USB_SS_PORT_LS_RX_DETECT, or
USB_SS_PORT_LS_COMP_MOD are valid states that do not indicate the need
for warm reset by themselves.

Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Kukjin Kim <kgene.kim@samsung.com>
Cc: Vincent Palatin <vpalatin@chromium.org>
Cc: Lan Tianyu <tianyu.lan@intel.com>
Cc: Ksenia Ragiadakou <burzalodowa@gmail.com>
Cc: Vivek Gautam <gautam.vivek@samsung.com>
Cc: Douglas Anderson <dianders@chromium.org>
Cc: Felipe Balbi <balbi@ti.com>
Cc: Sunil Joshi <joshi@samsung.com>
Cc: Hans de Goede <hdegoede@redhat.com>
Acked-by: default avatarJulius Werner <jwerner@chromium.org>
Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
Acked-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 51df62ff

drivers/usb/core/hub.c

+25 −11
Original line number Diff line number Diff line
@@ -2587,13 +2587,20 @@ static int hub_port_reset(struct usb_hub *hub, int port1, 
/* Is a USB 3.0 port in the Inactive or Compliance Mode state?

 * Port worm reset is required to recover

 */

static bool hub_port_warm_reset_required(struct usb_hub *hub, u16 portstatus)

static bool hub_port_warm_reset_required(struct usb_hub *hub, int port1,

		u16 portstatus)

{

	return hub_is_superspeed(hub->hdev) &&

		(((portstatus & USB_PORT_STAT_LINK_STATE) ==

		  USB_SS_PORT_LS_SS_INACTIVE) ||

		 ((portstatus & USB_PORT_STAT_LINK_STATE) ==

		  USB_SS_PORT_LS_COMP_MOD)) ;

	u16 link_state;



	if (!hub_is_superspeed(hub->hdev))

		return false;



	if (test_bit(port1, hub->warm_reset_bits))

		return true;



	link_state = portstatus & USB_PORT_STAT_LINK_STATE;

	return link_state == USB_SS_PORT_LS_SS_INACTIVE

		|| link_state == USB_SS_PORT_LS_COMP_MOD;

}



static int hub_port_wait_reset(struct usb_hub *hub, int port1,
@@ -2630,7 +2637,7 @@ static int hub_port_wait_reset(struct usb_hub *hub, int port1, 
	if ((portstatus & USB_PORT_STAT_RESET))

		return -EBUSY;



	if (hub_port_warm_reset_required(hub, portstatus))

	if (hub_port_warm_reset_required(hub, port1, portstatus))

		return -ENOTCONN;



	/* Device went away? */
@@ -2730,9 +2737,10 @@ static int hub_port_reset(struct usb_hub *hub, int port1, 
		if (status < 0)

			goto done;



		if (hub_port_warm_reset_required(hub, portstatus))

		if (hub_port_warm_reset_required(hub, port1, portstatus))

			warm = true;

	}

	clear_bit(port1, hub->warm_reset_bits);



	/* Reset the port */

	for (i = 0; i < PORT_RESET_TRIES; i++) {
@@ -2769,7 +2777,8 @@ static int hub_port_reset(struct usb_hub *hub, int port1, 
					&portstatus, &portchange) < 0)

				goto done;



			if (!hub_port_warm_reset_required(hub, portstatus))

			if (!hub_port_warm_reset_required(hub, port1,

					portstatus))

				goto done;



			/*
@@ -2856,8 +2865,13 @@ static int check_port_resume_type(struct usb_device *udev, 
{

	struct usb_port *port_dev = hub->ports[port1 - 1];



	/* Is a warm reset needed to recover the connection? */

	if (status == 0 && udev->reset_resume

		&& hub_port_warm_reset_required(hub, port1, portstatus)) {

		/* pass */;

	}

	/* Is the device still present? */

	if (status || port_is_suspended(hub, portstatus) ||

	else if (status || port_is_suspended(hub, portstatus) ||

			!port_is_power_on(hub, portstatus) ||

			!(portstatus & USB_PORT_STAT_CONNECTION)) {

		if (status >= 0)
@@ -4872,7 +4886,7 @@ static void port_event(struct usb_hub *hub, int port1) 
	 * Warm reset a USB3 protocol port if it's in

	 * SS.Inactive state.

	 */

	if (hub_port_warm_reset_required(hub, portstatus)) {

	if (hub_port_warm_reset_required(hub, port1, portstatus)) {

		dev_dbg(&port_dev->dev, "do warm reset\n");

		if (!udev || !(portstatus & USB_PORT_STAT_CONNECTION)

				|| udev->state == USB_STATE_NOTATTACHED) {

drivers/usb/core/hub.h

+2 −0
Original line number Diff line number Diff line
@@ -52,6 +52,8 @@ struct usb_hub { 
	unsigned long		power_bits[1]; /* ports that are powered */

	unsigned long		child_usage_bits[1]; /* ports powered on for

							children */

	unsigned long		warm_reset_bits[1]; /* ports requesting warm

							reset recovery */

#if USB_MAXCHILDREN > 31 /* 8*sizeof(unsigned long) - 1 */

#error event_bits[] is too short!

#endif

drivers/usb/core/port.c

+12 −9
Original line number Diff line number Diff line
@@ -103,16 +103,19 @@ static int usb_port_runtime_resume(struct device *dev) 
	msleep(hub_power_on_good_delay(hub));

	if (udev && !retval) {

		/*

		 * Attempt to wait for usb hub port to be reconnected in order

		 * to make the resume procedure successful.  The device may have

		 * disconnected while the port was powered off, so ignore the

		 * return status.

		 * Our preference is to simply wait for the port to reconnect,

		 * as that is the lowest latency method to restart the port.

		 * However, there are cases where toggling port power results in

		 * the host port and the device port getting out of sync causing

		 * a link training live lock.  Upon timeout, flag the port as

		 * needing warm reset recovery (to be performed later by

		 * usb_port_resume() as requested via usb_wakeup_notification())

		 */

		retval = hub_port_debounce_be_connected(hub, port1);

		if (retval < 0)

			dev_dbg(&port_dev->dev, "can't get reconnection after setting port  power on, status %d\n",

					retval);

		retval = 0;

		if (hub_port_debounce_be_connected(hub, port1) < 0) {

			dev_dbg(&port_dev->dev, "reconnect timeout\n");

			if (hub_is_superspeed(hdev))

				set_bit(port1, hub->warm_reset_bits);

		}



		/* Force the child awake to revalidate after the power loss. */

		if (!test_and_set_bit(port1, hub->child_usage_bits)) {