USB: EHCI: use hrtimer for the periodic schedule

This patch (as1573) adds hrtimer support for managing ehci-hcd's
periodic schedule.  There are two issues to deal with.

First, the schedule's state (on or off) must not be changed until the
hardware status has caught up with the current command.  This is
handled by an hrtimer event that polls at 1-ms intervals to see when
the Periodic Schedule Status (PSS) flag matches the Periodic Schedule
Enable (PSE) value.

Second, the schedule should not be turned off as soon as it becomes
empty.  Turning the schedule on and off takes time, so we want to wait
until the schedule has been empty for a suitable period before turning
it off.  This is handled by an hrtimer event that gets set to expire
10 ms after the periodic schedule becomes empty.

The existing code polls (for up to 1125 us and with interrupts
disabled!) to check the status, and doesn't implement a delay before
turning off the schedule.  Furthermore, if the polling fails then the
driver decides that the controller has died.  This has caused problems
for several people; some controllers can take 10 ms or more to turn
off their periodic schedules.

This patch fixes these issues.  It also makes the "broken_periodic"
workaround unnecessary; there is no longer any danger of turning off
the periodic schedule after it has been on for less than 1 ms.

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

1 files changed, 5 insertions, 2 deletions

diff --git a/drivers/usb/host/ehci.h b/drivers/usb/host/ehci.h
index 070be83028d5..da2e0ab23850 100644
--- a/drivers/usb/host/ehci.h
+++ b/drivers/usb/host/ehci.h
@@ -79,6 +79,8 @@ enum ehci_rh_state {
  * ehci-timer.c) in parallel with this list.
  */
 enum ehci_hrtimer_event {
+	EHCI_HRTIMER_POLL_PSS,		/* Poll for periodic schedule off */
+	EHCI_HRTIMER_DISABLE_PERIODIC,	/* Wait to disable periodic sched */
 	EHCI_HRTIMER_NUM_EVENTS		/* Must come last */
 };
 #define EHCI_HRTIMER_NO_EVENT	99
@@ -90,6 +92,8 @@ struct ehci_hcd {			/* one per controller */
 	ktime_t			hr_timeouts[EHCI_HRTIMER_NUM_EVENTS];
 	struct hrtimer		hrtimer;
 
+	int			PSS_poll_count;
+
 	/* glue to PCI and HCD framework */
 	struct ehci_caps __iomem *caps;
 	struct ehci_regs __iomem *regs;
@@ -116,7 +120,7 @@ struct ehci_hcd {			/* one per controller */
 
 	union ehci_shadow	*pshadow;	/* mirror hw periodic table */
 	int			next_uframe;	/* scan periodic, start here */
-	unsigned		periodic_sched;	/* periodic activity count */
+	unsigned		periodic_count;	/* periodic activity count */
 	unsigned		uframe_periodic_max; /* max periodic time per uframe */
 
 
@@ -165,7 +169,6 @@ struct ehci_hcd {			/* one per controller */
 	unsigned		big_endian_capbase:1;
 	unsigned		has_amcc_usb23:1;
 	unsigned		need_io_watchdog:1;
-	unsigned		broken_periodic:1;
 	unsigned		amd_pll_fix:1;
 	unsigned		fs_i_thresh:1;	/* Intel iso scheduling */
 	unsigned		use_dummy_qh:1;	/* AMD Frame List table quirk*/