linux-kernel - [PATCH 3.16 029/136] xhci: Check all endpoints for LPM timeout

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Date:   Tue, 17 Dec 2019 00:46:03 +0000
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>,
        "Philipp Zabel" <p.zabel@...gutronix.de>,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
        "Mathias Nyman" <mathias.nyman@...ux.intel.com>,
        "Jan Schmidt" <jan@...tricular.com>
Subject: [PATCH 3.16 029/136] xhci: Check all endpoints for LPM timeout

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

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

From: Jan Schmidt <jan@...tricular.com>

commit d500c63f80f2ea08ee300e57da5f2af1c13875f5 upstream.

If an endpoint is encountered that returns USB3_LPM_DEVICE_INITIATED, keep
checking further endpoints, as there might be periodic endpoints later
that return USB3_LPM_DISABLED due to shorter service intervals.

Without this, the code can set too high a maximum-exit-latency and
prevent the use of multiple USB3 cameras that should be able to work.

Signed-off-by: Jan Schmidt <jan@...tricular.com>
Tested-by: Philipp Zabel <p.zabel@...gutronix.de>
Signed-off-by: Mathias Nyman <mathias.nyman@...ux.intel.com>
Link: https://lore.kernel.org/r/1570190373-30684-4-git-send-email-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/usb/host/xhci.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -4503,12 +4503,12 @@ static int xhci_update_timeout_for_endpo
 	alt_timeout = xhci_call_host_update_timeout_for_endpoint(xhci, udev,
 		desc, state, timeout);
 
-	/* If we found we can't enable hub-initiated LPM, or
+	/* If we found we can't enable hub-initiated LPM, and
 	 * the U1 or U2 exit latency was too high to allow
-	 * device-initiated LPM as well, just stop searching.
+	 * device-initiated LPM as well, then we will disable LPM
+	 * for this device, so stop searching any further.
 	 */
-	if (alt_timeout == USB3_LPM_DISABLED ||
-			alt_timeout == USB3_LPM_DEVICE_INITIATED) {
+	if (alt_timeout == USB3_LPM_DISABLED) {
 		*timeout = alt_timeout;
 		return -E2BIG;
 	}