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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: Julius Werner <jwerner@chromium.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Dan Williams 2014-05-29 12:58:46 -07:00 committed by Greg Kroah-Hartman
parent 51df62ff74
commit 3cd12f9151
3 changed files with 39 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

36
drivers/usb/core/hub.c
View File

@ -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) {

2
drivers/usb/core/hub.h
View File

@ -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

21
drivers/usb/core/port.c
View File

@ -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)) {