USB: EHCI: use hrtimer for unlinking empty async QHs

This patch (as1583) changes ehci-hcd to use an hrtimer event for
unlinking empty (unused) async QHs instead of using a kernel timer.

The check for empty QHs is moved to a new routine, where it doesn't
require going through an entire scan of both the async and periodic
schedules.  And it can unlink multiple QHs at once, unlike the current
code.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 1 insertions, 15 deletions

diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index 86e8ee169c67..74ffd20edff8 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -94,8 +94,6 @@ static const char	hcd_name [] = "ehci_hcd";
 #define EHCI_TUNE_FLS           1       /* (medium) 512-frame schedule */
 
 #define EHCI_IO_JIFFIES         (HZ/10)         /* io watchdog > irq_thresh */
-#define EHCI_SHRINK_JIFFIES     (DIV_ROUND_UP(HZ, 200) + 1)
-                                                /* 5-ms async qh unlink delay */
 
 /* Initial IRQ latency:  faster than hw default */
 static int log2_irq_thresh = 0;         // 0 to 6
@@ -130,15 +128,6 @@ MODULE_PARM_DESC(hird, "host initiated resume duration, +1 for each 75us");
 static void
 timer_action(struct ehci_hcd *ehci, enum ehci_timer_action action)
 {
-        /* Don't override timeouts which shrink or (later) disable
-         * the async ring; just the I/O watchdog.  Note that if a
-         * SHRINK were pending, OFF would never be requested.
-         */
-        if (timer_pending(&ehci->watchdog)
-                        && (BIT(TIMER_ASYNC_SHRINK)
-                                & ehci->actions))
-                return;
-
         if (!test_and_set_bit(action, &ehci->actions)) {
                 unsigned long t;
 
@@ -148,10 +137,6 @@ timer_action(struct ehci_hcd *ehci, enum ehci_timer_action action)
                                 return;
                         t = EHCI_IO_JIFFIES;
                         break;
-                /* case TIMER_ASYNC_SHRINK: */
-                default:
-                        t = EHCI_SHRINK_JIFFIES;
-                        break;
                 }
                 mod_timer(&ehci->watchdog, t + jiffies);
         }
@@ -307,6 +292,7 @@ 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 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);