Patch "usb: hub: Allow reset retry for USB2 devices on connect bounce" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

usb: hub: Allow reset retry for USB2 devices on connect bounce

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
usb-hub-allow-reset-retry-for-usb2-devices-on-connect-bounce.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Mathias Nyman <[email protected]>
Date: Tue, 17 Oct 2017 16:07:33 +0300
Subject: usb: hub: Allow reset retry for USB2 devices on connect bounce

From: Mathias Nyman <[email protected]>

commit 1ac7db63333db1eeff901bfd6bbcd502b4634fa4 upstream.

If the connect status change is set during reset signaling, but the status remains connected just retry port reset.

This solves an issue with connecting a 90W HP Thunderbolt 3 dock with a Lenovo Carbon x1 (5th generation) which causes a 30min loop of a high speed device being re-discovererd before usb ports starts working.

[...]

[ 389.023845] usb 3-1: new high-speed USB device number 55 using xhci_hcd
[ 389.491841] usb 3-1: new high-speed USB device number 56 using xhci_hcd
[ 389.959928] usb 3-1: new high-speed USB device number 57 using xhci_hcd

[...]

This is caused by a high speed device that doesn't successfully go to the enabled state after the second port reset. Instead the connection bounces (connected, with connect status change), bailing out completely from enumeration just to restart from scratch.

---
 drivers/usb/core/hub.c |   11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

@@ -2656,13 +2656,16 @@ static int hub_port_wait_reset(struct us
 	if (!(portstatus & USB_PORT_STAT_CONNECTION))
 		return -ENOTCONN;
 
-	/* bomb out completely if the connection bounced.  A USB 3.0
-	 * connection may bounce if multiple warm resets were issued,
+	/* Retry if connect change is set but status is still connected.
+	 * A USB 3.0 connection may bounce if multiple warm resets were issued,
 	 * but the device may have successfully re-connected. Ignore it.
 	 */
 	if (!hub_is_superspeed(hub->hdev) &&
-			(portchange & USB_PORT_STAT_C_CONNECTION))
-		return -ENOTCONN;
+	    (portchange & USB_PORT_STAT_C_CONNECTION)) {
+		usb_clear_port_feature(hub->hdev, port1,
+				       USB_PORT_FEAT_C_CONNECTION);
+		return -EAGAIN;
+	}
 
 	if (!(portstatus & USB_PORT_STAT_ENABLE))
 		return -EBUSY;

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/usb-hub-allow-reset-retry-for-usb2-devices-on-connect-bounce.patch