patch "usb: hub: Allow reset retry for USB2 devices on connect bounce" added to usb-linus

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 my usb git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

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

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(-)

index b5c733613823..e9ce6bb0b22d 100644
@@ -2710,13 +2710,16 @@ static int hub_port_wait_reset(struct usb_hub *hub, int port1,
 	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;

2.14.2