This patch introduces ehci_disable_event(), which is applied on
IAA_WATCHDOG and START_UNLINK_INTR timeouts if the two corresponding
events(IAA and intr URB submission) happened, so that we may avoid
unnecessary CPU wakeup by canceling the timer.
One simple test indicates about 7~8 timer expirations/sec
(20% ~ 30% of totoal timer expirations/sec) can be saved when one asix
network NIC is connected to EHCI without network traffic(the device
responds interrupt poll 7~8 times per second constantly for link status
query).
Cc: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxxxxx>
---
drivers/usb/host/ehci-hcd.c | 12 +-----------
drivers/usb/host/ehci-sched.c | 4 +++-
drivers/usb/host/ehci-timer.c | 16 ++++++++++++++++
3 files changed, 20 insertions(+), 12 deletions(-)
diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index 73c7299..549da36 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -738,17 +738,7 @@ static irqreturn_t ehci_irq (struct usb_hcd *hcd)
if (status & STS_IAA) {
/* Turn off the IAA watchdog */
- ehci->enabled_hrtimer_events &= ~BIT(EHCI_HRTIMER_IAA_WATCHDOG);
-
- /*
- * Mild optimization: Allow another IAAD to reset the
- * hrtimer, if one occurs before the next expiration.
- * In theory we could always cancel the hrtimer, but
- * tests show that about half the time it will be reset
- * for some other event anyway.
- */
- if (ehci->next_hrtimer_event == EHCI_HRTIMER_IAA_WATCHDOG)
- ++ehci->next_hrtimer_event;
+ ehci_disable_event(ehci, EHCI_HRTIMER_IAA_WATCHDOG);
/* guard against (alleged) silicon errata */
if (cmd & CMD_IAAD)
diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c
index 6631089..83be03f 100644
--- a/drivers/usb/host/ehci-sched.c
+++ b/drivers/usb/host/ehci-sched.c
@@ -610,9 +610,11 @@ static void cancel_unlink_wait_intr(struct ehci_hcd *ehci, struct ehci_qh *qh)
list_del_init(&qh->unlink_node);
/*
- * TODO: disable the event of EHCI_HRTIMER_START_UNLINK_INTR for
+ * disable the event of EHCI_HRTIMER_START_UNLINK_INTR for
* avoiding unnecessary CPU wakeup
*/
+ if (list_empty(&ehci->intr_unlink_wait))
+ ehci_disable_event(ehci, EHCI_HRTIMER_START_UNLINK_INTR);
}
static void start_unlink_intr(struct ehci_hcd *ehci, struct ehci_qh *qh)
diff --git a/drivers/usb/host/ehci-timer.c b/drivers/usb/host/ehci-timer.c
index 424ac5d..983d063 100644
--- a/drivers/usb/host/ehci-timer.c
+++ b/drivers/usb/host/ehci-timer.c
@@ -99,6 +99,22 @@ static void ehci_enable_event(struct ehci_hcd *ehci, unsigned event,
}
}
+/* Warning: don't call this function from hrtimer handler context */
+static void ehci_disable_event(struct ehci_hcd *ehci, unsigned event)
+{
+ ehci->enabled_hrtimer_events &= ~(1 << event);
+
+ if (!ehci->enabled_hrtimer_events) {
+ ehci->next_hrtimer_event = EHCI_HRTIMER_NO_EVENT;
+ hrtimer_cancel(&ehci->hrtimer);
+ } else if (ehci->next_hrtimer_event == event) {
+ ehci->next_hrtimer_event = EHCI_HRTIMER_NO_EVENT;
+ ehci_enable_event(ehci,
+ ffs(ehci->enabled_hrtimer_events) - 1,
+ false);
+ }
+}
+
/* Poll the STS_ASS status bit; see when it agrees with CMD_ASE */
static void ehci_poll_ASS(struct ehci_hcd *ehci)
--
1.7.9.5
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