This is a note to let you know that I've just added the patch titled
USB: EHCI: fix regression during bus resume
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 2a40f324541ee61c22146214349c2ce9f5c30bcf Mon Sep 17 00:00:00 2001
From: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Date: Fri, 15 Mar 2013 14:40:26 -0400
Subject: USB: EHCI: fix regression during bus resume
This patch (as1663) fixes a regression caused by commit
6e0c3339a6f19d748f16091d0a05adeb1e1f822b (USB: EHCI: unlink one async
QH at a time). In order to avoid keeping multiple QHs in an unusable
intermediate state, that commit changed unlink_empty_async() so that
it unlinks only one empty QH at a time.
However, when the EHCI root hub is suspended, _all_ async QHs need to
be unlinked. ehci_bus_suspend() used to do this by calling
unlink_empty_async(), but now this only unlinks one of the QHs, not
all of them.
The symptom is that when the root hub is resumed, USB communications
don't work for some period of time. This is because ehci-hcd doesn't
realize it needs to restart the async schedule; it assumes that
because some QHs are already on the schedule, the schedule must be
running.
The easiest way to fix the problem is add a new function that unlinks
all the async QHs when the root hub is suspended.
This patch should be applied to all kernels that have the 6e0c3339a6f1
commit.
Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Reported-and-tested-by: Adrian Bassett <adrian.bassett@xxxxxxxxxxxxx>
Cc: stable <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/usb/host/ehci-hcd.c | 1 +
drivers/usb/host/ehci-hub.c | 2 +-
drivers/usb/host/ehci-q.c | 13 +++++++++++++
3 files changed, 15 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index 5726cb1..416a6dc 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -302,6 +302,7 @@ static void ehci_quiesce (struct ehci_hcd *ehci)
static void end_unlink_async(struct ehci_hcd *ehci);
static void unlink_empty_async(struct ehci_hcd *ehci);
+static void unlink_empty_async_suspended(struct ehci_hcd *ehci);
static void ehci_work(struct ehci_hcd *ehci);
static void start_unlink_intr(struct ehci_hcd *ehci, struct ehci_qh *qh);
static void end_unlink_intr(struct ehci_hcd *ehci, struct ehci_qh *qh);
diff --git a/drivers/usb/host/ehci-hub.c b/drivers/usb/host/ehci-hub.c
index 4d3b294..7d06e77 100644
--- a/drivers/usb/host/ehci-hub.c
+++ b/drivers/usb/host/ehci-hub.c
@@ -328,7 +328,7 @@ static int ehci_bus_suspend (struct usb_hcd *hcd)
ehci->rh_state = EHCI_RH_SUSPENDED;
end_unlink_async(ehci);
- unlink_empty_async(ehci);
+ unlink_empty_async_suspended(ehci);
ehci_handle_intr_unlinks(ehci);
end_free_itds(ehci);
diff --git a/drivers/usb/host/ehci-q.c b/drivers/usb/host/ehci-q.c
index 5464665..23d1369 100644
--- a/drivers/usb/host/ehci-q.c
+++ b/drivers/usb/host/ehci-q.c
@@ -1316,6 +1316,19 @@ static void unlink_empty_async(struct ehci_hcd *ehci)
}
}
+/* The root hub is suspended; unlink all the async QHs */
+static void unlink_empty_async_suspended(struct ehci_hcd *ehci)
+{
+ struct ehci_qh *qh;
+
+ while (ehci->async->qh_next.qh) {
+ qh = ehci->async->qh_next.qh;
+ WARN_ON(!list_empty(&qh->qtd_list));
+ single_unlink_async(ehci, qh);
+ }
+ start_iaa_cycle(ehci, false);
+}
+
/* makes sure the async qh will become idle */
/* caller must own ehci->lock */
--
1.8.1.rc1.5.g7e0651a
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