[PATCH 3.16 024/254] usb: hub: Cycle HUB power when initialization fails

[Ben Hutchings]

3.16.55-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Mike Looijmans <mike.looijmans@xxxxxxxx>

commit 973593a960ddac0f14f0d8877d2d0abe0afda795 upstream.

Sometimes the USB device gets confused about the state of the initialization and
the connection fails. In particular, the device thinks that it's already set up
and running while the host thinks the device still needs to be configured. To
work around this issue, power-cycle the hub's output to issue a sort of "reset"
to the device. This makes the device restart its state machine and then the
initialization succeeds.

This fixes problems where the kernel reports a list of errors like this:

usb 1-1.3: device not accepting address 19, error -71

The end result is a non-functioning device. After this patch, the sequence
becomes like this:

usb 1-1.3: new high-speed USB device number 18 using ci_hdrc
usb 1-1.3: device not accepting address 18, error -71
usb 1-1.3: new high-speed USB device number 19 using ci_hdrc
usb 1-1.3: device not accepting address 19, error -71
usb 1-1-port3: attempt power cycle
usb 1-1.3: new high-speed USB device number 21 using ci_hdrc
usb-storage 1-1.3:1.2: USB Mass Storage device detected

Signed-off-by: Mike Looijmans <mike.looijmans@xxxxxxxx>
Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/usb/core/hub.c | 9 +++++++++
 1 file changed, 9 insertions(+)

--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -4792,6 +4792,15 @@ loop:
 		usb_put_dev(udev);
 		if ((status == -ENOTCONN) || (status == -ENOTSUPP))
 			break;
+
+		/* When halfway through our retry count, power-cycle the port */
+		if (i == (SET_CONFIG_TRIES / 2) - 1) {
+			dev_info(&port_dev->dev, "attempt power cycle\n");
+			usb_hub_set_port_power(hdev, hub, port1, false);
+			msleep(2 * hub_power_on_good_delay(hub));
+			usb_hub_set_port_power(hdev, hub, port1, true);
+			msleep(hub_power_on_good_delay(hub));
+		}
 	}
 	if (hub->hdev->parent ||
 			!hcd->driver->port_handed_over ||