This is a note to let you know that I've just added the patch titled
xhci: Improve detection of device initiated wake signal.
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:
xhci-improve-detection-of-device-initiated-wake-signal.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 <stable@xxxxxxxxxxxxxxx> know about it.
>From 253f588c70f66184b1f3a9bbb428b49bbda73e80 Mon Sep 17 00:00:00 2001
From: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
Date: Thu, 11 Mar 2021 13:53:51 +0200
Subject: xhci: Improve detection of device initiated wake signal.
From: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
commit 253f588c70f66184b1f3a9bbb428b49bbda73e80 upstream.
A xHC USB 3 port might miss the first wake signal from a USB 3 device
if the port LFPS reveiver isn't enabled fast enough after xHC resume.
xHC host will anyway be resumed by a PME# signal, but will go back to
suspend if no port activity is seen.
The device resends the U3 LFPS wake signal after a 100ms delay, but
by then host is already suspended, starting all over from the
beginning of this issue.
USB 3 specs say U3 wake LFPS signal is sent for max 10ms, then device
needs to delay 100ms before resending the wake.
Don't suspend immediately if port activity isn't detected in resume.
Instead add a retry. If there is no port activity then delay for 120ms,
and re-check for port activity.
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20210311115353.2137560-3-mathias.nyman@xxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/usb/host/xhci.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -1018,6 +1018,7 @@ int xhci_resume(struct xhci_hcd *xhci, b
struct usb_hcd *secondary_hcd;
int retval = 0;
bool comp_timer_running = false;
+ bool pending_portevent = false;
if (!hcd->state)
return 0;
@@ -1151,13 +1152,22 @@ int xhci_resume(struct xhci_hcd *xhci, b
done:
if (retval == 0) {
- /* Resume root hubs only when have pending events. */
- if (xhci_pending_portevent(xhci)) {
+ /*
+ * Resume roothubs only if there are pending events.
+ * USB 3 devices resend U3 LFPS wake after a 100ms delay if
+ * the first wake signalling failed, give it that chance.
+ */
+ pending_portevent = xhci_pending_portevent(xhci);
+ if (!pending_portevent) {
+ msleep(120);
+ pending_portevent = xhci_pending_portevent(xhci);
+ }
+
+ if (pending_portevent) {
usb_hcd_resume_root_hub(xhci->shared_hcd);
usb_hcd_resume_root_hub(hcd);
}
}
-
/*
* If system is subject to the Quirk, Compliance Mode Timer needs to
* be re-initialized Always after a system resume. Ports are subject
Patches currently in stable-queue which might be from mathias.nyman@xxxxxxxxxxxxxxx are
queue-4.4/xhci-improve-detection-of-device-initiated-wake-signal.patch
