linux-kernel - [PATCH 3.16 286/305] xhci: Don't prevent USB2 bus suspend in state check intended for USB3 only

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Message-ID: <lsq.1549201508.68116158@decadent.org.uk>
Date:   Sun, 03 Feb 2019 14:45:08 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Mathias Nyman" <mathias.nyman@...ux.intel.com>,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>
Subject: [PATCH 3.16 286/305] xhci: Don't prevent USB2 bus suspend in
 state check intended for USB3 only

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

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

From: Mathias Nyman <mathias.nyman@...ux.intel.com>

commit 45f750c16cae3625014c14c77bd9005eda975d35 upstream.

The code to prevent a bus suspend if a USB3 port was still in link training
also reacted to USB2 port polling state.
This caused bus suspend to busyloop in some cases.
USB2 polling state is different from USB3, and should not prevent bus
suspend.

Limit the USB3 link training state check to USB3 root hub ports only.
The origial commit went to stable so this need to be applied there as well

Fixes: 2f31a67f01a8 ("usb: xhci: Prevent bus suspend if a port connect change or polling state is detected")
Signed-off-by: Mathias Nyman <mathias.nyman@...ux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/usb/host/xhci-hub.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/usb/host/xhci-hub.c
+++ b/drivers/usb/host/xhci-hub.c
@@ -1205,7 +1205,8 @@ int xhci_bus_suspend(struct usb_hcd *hcd
 		portsc_buf[port_index] = 0;
 
 		/* Bail out if a USB3 port has a new device in link training */
-		if ((t1 & PORT_PLS_MASK) == XDEV_POLLING) {
+		if ((hcd->speed >= HCD_USB3) &&
+		    (t1 & PORT_PLS_MASK) == XDEV_POLLING) {
 			bus_state->bus_suspended = 0;
 			spin_unlock_irqrestore(&xhci->lock, flags);
 			xhci_dbg(xhci, "Bus suspend bailout, port in polling\n");