From 2a40f324541ee61c22146214349c2ce9f5c30bcf Mon Sep 17 00:00:00 2001 From: Alan Stern 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 Reported-and-tested-by: Adrian Bassett Cc: stable Signed-off-by: Greg Kroah-Hartman --- 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(-) (limited to 'drivers') diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c index 5726cb144abf..416a6dce5e11 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 4d3b294f203e..7d06e77f6c4f 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 5464665f0b6a..23d136904285 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 */ -- cgit v1.2.3