This is a note to let you know that I've just added the patch titled
USB: EHCI: remove ASS/PSS polling timeout
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 55bcdce8a8228223ec4d17d8ded8134ed265d2c5 Mon Sep 17 00:00:00 2001
From: Alan Stern <[email protected]>
Date: Fri, 25 Jan 2013 16:52:45 -0500
Subject: USB: EHCI: remove ASS/PSS polling timeout
This patch (as1647) attempts to work around a problem that seems to
affect some nVidia EHCI controllers. They sometimes take a very long
time to turn off their async or periodic schedules. I don't know if
this is a result of other problems, but in any case it seems wise not
to depend on schedule enables or disables taking effect in any
specific length of time.
The patch removes the existing 20-ms timeout for enabling and
disabling the schedules. The driver will now continue to poll the
schedule state at 1-ms intervals until the controller finally decides
to obey the most recent command issued by the driver. Just in case
this hides a problem, a debugging message will be logged if the
controller takes longer than 20 polls.
I don't know if this will actually fix anything, but it can't hurt.
Signed-off-by: Alan Stern <[email protected]>
Tested-by: Piergiorgio Sartor <[email protected]>
CC: <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/usb/host/ehci-timer.c | 29 +++++++++++++++--------------
1 file changed, 15 insertions(+), 14 deletions(-)
diff --git a/drivers/usb/host/ehci-timer.c b/drivers/usb/host/ehci-timer.c
index 20dbdcb..f904071 100644
--- a/drivers/usb/host/ehci-timer.c
+++ b/drivers/usb/host/ehci-timer.c
@@ -113,14 +113,15 @@ static void ehci_poll_ASS(struct ehci_hcd *ehci)
if (want != actual) {
- /* Poll again later, but give up after about 20 ms */
- if (ehci->ASS_poll_count++ < 20) {
- ehci_enable_event(ehci, EHCI_HRTIMER_POLL_ASS, true);
- return;
- }
- ehci_dbg(ehci, "Waited too long for the async schedule status
(%x/%x), giving up\n",
- want, actual);
+ /* Poll again later */
+ ehci_enable_event(ehci, EHCI_HRTIMER_POLL_ASS, true);
+ ++ehci->ASS_poll_count;
+ return;
}
+
+ if (ehci->ASS_poll_count > 20)
+ ehci_dbg(ehci, "ASS poll count reached %d\n",
+ ehci->ASS_poll_count);
ehci->ASS_poll_count = 0;
/* The status is up-to-date; restart or stop the schedule as needed */
@@ -159,14 +160,14 @@ static void ehci_poll_PSS(struct ehci_hcd *ehci)
if (want != actual) {
- /* Poll again later, but give up after about 20 ms */
- if (ehci->PSS_poll_count++ < 20) {
- ehci_enable_event(ehci, EHCI_HRTIMER_POLL_PSS, true);
- return;
- }
- ehci_dbg(ehci, "Waited too long for the periodic schedule
status (%x/%x), giving up\n",
- want, actual);
+ /* Poll again later */
+ ehci_enable_event(ehci, EHCI_HRTIMER_POLL_PSS, true);
+ return;
}
+
+ if (ehci->PSS_poll_count > 20)
+ ehci_dbg(ehci, "PSS poll count reached %d\n",
+ ehci->PSS_poll_count);
ehci->PSS_poll_count = 0;
/* The status is up-to-date; restart or stop the schedule as needed */
--
1.8.1.rc1.5.g7e0651a
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