USB: EHCI: use hrtimer for interrupt QH unlink
This patch (as1577) adds hrtimer support for unlinking interrupt QHs
in ehci-hcd. The current code relies on a fixed delay of either 2 or
55 us, which is not always adequate and in any case is totally bogus.
Thanks to internal caching, the EHCI hardware may continue to access
an interrupt QH for more than a millisecond after it has been unlinked.
In fact, the EHCI spec doesn't say how long to wait before using an
unlinked interrupt QH. The patch sets the delay to 9 microframes
minimum, which ought to be adequate.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index 21d6fbc..edcfd2c 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -309,6 +309,8 @@
static void end_unlink_async(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);
#include "ehci-timer.c"
#include "ehci-hub.c"
@@ -1034,7 +1036,7 @@
switch (qh->qh_state) {
case QH_STATE_LINKED:
case QH_STATE_COMPLETING:
- intr_deschedule (ehci, qh);
+ start_unlink_intr(ehci, qh);
break;
case QH_STATE_IDLE:
qh_completions (ehci, qh);
@@ -1164,7 +1166,7 @@
if (eptype == USB_ENDPOINT_XFER_BULK)
unlink_async(ehci, qh);
else
- intr_deschedule(ehci, qh);
+ start_unlink_intr(ehci, qh);
}
}
spin_unlock_irqrestore(&ehci->lock, flags);