USB: EHCI: use hrtimer for controller death

This patch (as1578) adds an hrtimer event to handle the death of an
EHCI controller.  When a controller dies, it doesn't necessarily stop
running right away.  The new event polls at 1-ms intervals to see when
all activity has safely stopped.  This replaces a busy-wait polling
loop in the current code.

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

1 files changed, 26 insertions, 0 deletions

diff --git a/drivers/usb/host/ehci-timer.c b/drivers/usb/host/ehci-timer.c
index bd8b591771b0..0c5326a8883c 100644
--- a/drivers/usb/host/ehci-timer.c
+++ b/drivers/usb/host/ehci-timer.c
@@ -69,6 +69,7 @@ static void ehci_clear_command_bit(struct ehci_hcd *ehci, u32 bit)
 static unsigned event_delays_ns[] = {
         1 * NSEC_PER_MSEC,      /* EHCI_HRTIMER_POLL_ASS */
         1 * NSEC_PER_MSEC,      /* EHCI_HRTIMER_POLL_PSS */
+        1 * NSEC_PER_MSEC,      /* EHCI_HRTIMER_POLL_DEAD */
         1125 * NSEC_PER_USEC,   /* EHCI_HRTIMER_UNLINK_INTR */
         10 * NSEC_PER_MSEC,     /* EHCI_HRTIMER_DISABLE_PERIODIC */
         15 * NSEC_PER_MSEC,     /* EHCI_HRTIMER_DISABLE_ASYNC */
@@ -193,6 +194,30 @@ static void ehci_disable_PSE(struct ehci_hcd *ehci)
 }
 
 
+/* Poll the STS_HALT status bit; see when a dead controller stops */
+static void ehci_handle_controller_death(struct ehci_hcd *ehci)
+{
+        if (!(ehci_readl(ehci, &ehci->regs->status) & STS_HALT)) {
+
+                /* Give up after a few milliseconds */
+                if (ehci->died_poll_count++ < 5) {
+                        /* Try again later */
+                        ehci_enable_event(ehci, EHCI_HRTIMER_POLL_DEAD, true);
+                        return;
+                }
+                ehci_warn(ehci, "Waited too long for the controller to stop, giving up\n");
+        }
+
+        /* Clean up the mess */
+        ehci->rh_state = EHCI_RH_HALTED;
+        ehci_writel(ehci, 0, &ehci->regs->configured_flag);
+        ehci_writel(ehci, 0, &ehci->regs->intr_enable);
+        ehci_work(ehci);
+
+        /* Not in process context, so don't try to reset the controller */
+}
+
+
 /* Handle unlinked interrupt QHs once they are gone from the hardware */
 static void ehci_handle_intr_unlinks(struct ehci_hcd *ehci)
 {
@@ -233,6 +258,7 @@ static void ehci_handle_intr_unlinks(struct ehci_hcd *ehci)
 static void (*event_handlers[])(struct ehci_hcd *) = {
         ehci_poll_ASS,                  /* EHCI_HRTIMER_POLL_ASS */
         ehci_poll_PSS,                  /* EHCI_HRTIMER_POLL_PSS */
+        ehci_handle_controller_death,   /* EHCI_HRTIMER_POLL_DEAD */
         ehci_handle_intr_unlinks,       /* EHCI_HRTIMER_UNLINK_INTR */
         ehci_disable_PSE,               /* EHCI_HRTIMER_DISABLE_PERIODIC */
         ehci_disable_ASE,               /* EHCI_HRTIMER_DISABLE_ASYNC */