summaryrefslogtreecommitdiffstats
path: root/drivers/usb/host
diff options
context:
space:
mode:
authorAlan Stern <stern@rowland.harvard.edu>2012-07-11 11:22:05 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-07-16 16:53:16 -0700
commit3ca9aebac2ebb8f56d2d097636b8c568320a9f87 (patch)
treead4382a904320043a32e8b18263bc22215ce5cee /drivers/usb/host
parentd58b4bcc6df8046cf9c3c59f9ff84d2cd86b93eb (diff)
downloadlinux-3ca9aebac2ebb8f56d2d097636b8c568320a9f87.tar.gz
linux-3ca9aebac2ebb8f56d2d097636b8c568320a9f87.tar.bz2
linux-3ca9aebac2ebb8f56d2d097636b8c568320a9f87.zip
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>
Diffstat (limited to 'drivers/usb/host')
-rw-r--r--drivers/usb/host/ehci-hcd.c2
-rw-r--r--drivers/usb/host/ehci-pci.c4
-rw-r--r--drivers/usb/host/ehci-sched.c69
-rw-r--r--drivers/usb/host/ehci-timer.c80
-rw-r--r--drivers/usb/host/ehci.h7
5 files changed, 101 insertions, 61 deletions
diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index f8fed163a23a..7e00ca095cea 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -546,7 +546,7 @@ static void ehci_work (struct ehci_hcd *ehci)
*/
if (ehci->rh_state == EHCI_RH_RUNNING &&
(ehci->async->qh_next.ptr != NULL ||
- ehci->periodic_sched != 0))
+ ehci->periodic_count != 0))
timer_action (ehci, TIMER_IO_WATCHDOG);
}
diff --git a/drivers/usb/host/ehci-pci.c b/drivers/usb/host/ehci-pci.c
index 21e5f963f331..2cb7d370c4ef 100644
--- a/drivers/usb/host/ehci-pci.c
+++ b/drivers/usb/host/ehci-pci.c
@@ -104,10 +104,6 @@ static int ehci_pci_setup(struct usb_hcd *hcd)
break;
case PCI_VENDOR_ID_INTEL:
ehci->fs_i_thresh = 1;
- if (pdev->device == 0x27cc) {
- ehci->broken_periodic = 1;
- ehci_info(ehci, "using broken periodic workaround\n");
- }
if (pdev->device == PCI_DEVICE_ID_INTEL_CE4100_USB)
hcd->has_tt = 1;
break;
diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c
index 3429b8a33c58..f5c15880c65a 100644
--- a/drivers/usb/host/ehci-sched.c
+++ b/drivers/usb/host/ehci-sched.c
@@ -481,67 +481,26 @@ static int tt_no_collision (
static int enable_periodic (struct ehci_hcd *ehci)
{
- int status;
-
- if (ehci->periodic_sched++)
+ if (ehci->periodic_count++)
return 0;
- /* did clearing PSE did take effect yet?
- * takes effect only at frame boundaries...
- */
- status = handshake_on_error_set_halt(ehci, &ehci->regs->status,
- STS_PSS, 0, 9 * 125);
- if (status) {
- usb_hc_died(ehci_to_hcd(ehci));
- return status;
- }
-
- ehci->command |= CMD_PSE;
- ehci_writel(ehci, ehci->command, &ehci->regs->command);
- /* posted write ... PSS happens later */
+ /* Stop waiting to turn off the periodic schedule */
+ ehci->enabled_hrtimer_events &= ~BIT(EHCI_HRTIMER_DISABLE_PERIODIC);
- /* make sure ehci_work scans these */
- ehci->next_uframe = ehci_read_frame_index(ehci)
- % (ehci->periodic_size << 3);
- if (unlikely(ehci->broken_periodic))
- ehci->last_periodic_enable = ktime_get_real();
+ /* Don't start the schedule until PSS is 0 */
+ ehci_poll_PSS(ehci);
return 0;
}
static int disable_periodic (struct ehci_hcd *ehci)
{
- int status;
-
- if (--ehci->periodic_sched)
+ if (--ehci->periodic_count)
return 0;
- if (unlikely(ehci->broken_periodic)) {
- /* delay experimentally determined */
- ktime_t safe = ktime_add_us(ehci->last_periodic_enable, 1000);
- ktime_t now = ktime_get_real();
- s64 delay = ktime_us_delta(safe, now);
-
- if (unlikely(delay > 0))
- udelay(delay);
- }
-
- /* did setting PSE not take effect yet?
- * takes effect only at frame boundaries...
- */
- status = handshake_on_error_set_halt(ehci, &ehci->regs->status,
- STS_PSS, STS_PSS, 9 * 125);
- if (status) {
- usb_hc_died(ehci_to_hcd(ehci));
- return status;
- }
-
- ehci->command &= ~CMD_PSE;
- ehci_writel(ehci, ehci->command, &ehci->regs->command);
- /* posted write ... */
-
- free_cached_lists(ehci);
+ ehci->next_uframe = -1; /* the periodic schedule is empty */
- ehci->next_uframe = -1;
+ /* Don't turn off the schedule until PSS is 1 */
+ ehci_poll_PSS(ehci);
return 0;
}
@@ -650,8 +609,7 @@ static int qh_unlink_periodic(struct ehci_hcd *ehci, struct ehci_qh *qh)
qh->qh_state = QH_STATE_UNLINK;
qh->qh_next.ptr = NULL;
- /* maybe turn off periodic schedule */
- return disable_periodic(ehci);
+ return 0;
}
static void intr_deschedule (struct ehci_hcd *ehci, struct ehci_qh *qh)
@@ -706,6 +664,9 @@ static void intr_deschedule (struct ehci_hcd *ehci, struct ehci_qh *qh)
ehci_err(ehci, "can't reschedule qh %p, err %d\n",
qh, rc);
}
+
+ /* maybe turn off periodic schedule */
+ disable_periodic(ehci);
}
/*-------------------------------------------------------------------------*/
@@ -2447,7 +2408,7 @@ restart:
/* assume completion callbacks modify the queue */
if (unlikely (modified)) {
- if (likely(ehci->periodic_sched > 0))
+ if (likely(ehci->periodic_count > 0))
goto restart;
/* short-circuit this scan */
now_uframe = clock;
@@ -2476,7 +2437,7 @@ restart:
unsigned now;
if (ehci->rh_state < EHCI_RH_RUNNING
- || ehci->periodic_sched == 0)
+ || ehci->periodic_count == 0)
break;
ehci->next_uframe = now_uframe;
now = ehci_read_frame_index(ehci) & (mod - 1);
diff --git a/drivers/usb/host/ehci-timer.c b/drivers/usb/host/ehci-timer.c
index f6279e2883a8..ecd3296157c6 100644
--- a/drivers/usb/host/ehci-timer.c
+++ b/drivers/usb/host/ehci-timer.c
@@ -16,6 +16,28 @@
/*-------------------------------------------------------------------------*/
+/* Set a bit in the USBCMD register */
+static void ehci_set_command_bit(struct ehci_hcd *ehci, u32 bit)
+{
+ ehci->command |= bit;
+ ehci_writel(ehci, ehci->command, &ehci->regs->command);
+
+ /* unblock posted write */
+ ehci_readl(ehci, &ehci->regs->command);
+}
+
+/* Clear a bit in the USBCMD register */
+static void ehci_clear_command_bit(struct ehci_hcd *ehci, u32 bit)
+{
+ ehci->command &= ~bit;
+ ehci_writel(ehci, ehci->command, &ehci->regs->command);
+
+ /* unblock posted write */
+ ehci_readl(ehci, &ehci->regs->command);
+}
+
+/*-------------------------------------------------------------------------*/
+
/*
* EHCI timer support... Now using hrtimers.
*
@@ -45,6 +67,8 @@
* the event types indexed by enum ehci_hrtimer_event in ehci.h.
*/
static unsigned event_delays_ns[] = {
+ 1 * NSEC_PER_MSEC, /* EHCI_HRTIMER_POLL_PSS */
+ 10 * NSEC_PER_MSEC, /* EHCI_HRTIMER_DISABLE_PERIODIC */
};
/* Enable a pending hrtimer event */
@@ -67,12 +91,68 @@ static void ehci_enable_event(struct ehci_hcd *ehci, unsigned event,
}
+/* Poll the STS_PSS status bit; see when it agrees with CMD_PSE */
+static void ehci_poll_PSS(struct ehci_hcd *ehci)
+{
+ unsigned actual, want;
+
+ /* Don't do anything if the controller isn't running (e.g., died) */
+ if (ehci->rh_state != EHCI_RH_RUNNING)
+ return;
+
+ want = (ehci->command & CMD_PSE) ? STS_PSS : 0;
+ actual = ehci_readl(ehci, &ehci->regs->status) & STS_PSS;
+
+ if (want != actual) {
+
+ /* Poll again later, but give up after about 20 ms */
+ if (ehci->PSS_poll_count++ < 20) {
+ ehci_enable_event(ehci, EHCI_HRTIMER_POLL_PSS, true);
+ return;
+ }
+ ehci_warn(ehci, "Waited too long for the periodic schedule status, giving up\n");
+ }
+ ehci->PSS_poll_count = 0;
+
+ /* The status is up-to-date; restart or stop the schedule as needed */
+ if (want == 0) { /* Stopped */
+ free_cached_lists(ehci);
+ if (ehci->periodic_count > 0) {
+
+ /* make sure ehci_work scans these */
+ ehci->next_uframe = ehci_read_frame_index(ehci)
+ & ((ehci->periodic_size << 3) - 1);
+ ehci_set_command_bit(ehci, CMD_PSE);
+ }
+
+ } else { /* Running */
+ if (ehci->periodic_count == 0) {
+
+ /* Turn off the schedule after a while */
+ ehci_enable_event(ehci, EHCI_HRTIMER_DISABLE_PERIODIC,
+ true);
+ }
+ }
+}
+
+/* Turn off the periodic schedule after a brief delay */
+static void ehci_disable_PSE(struct ehci_hcd *ehci)
+{
+ ehci_clear_command_bit(ehci, CMD_PSE);
+
+ /* Poll to see when it actually stops */
+ ehci_enable_event(ehci, EHCI_HRTIMER_POLL_PSS, true);
+}
+
+
/*
* Handler functions for the hrtimer event types.
* Keep this array in the same order as the event types indexed by
* enum ehci_hrtimer_event in ehci.h.
*/
static void (*event_handlers[])(struct ehci_hcd *) = {
+ ehci_poll_PSS, /* EHCI_HRTIMER_POLL_PSS */
+ ehci_disable_PSE, /* EHCI_HRTIMER_DISABLE_PERIODIC */
};
static enum hrtimer_restart ehci_hrtimer_func(struct hrtimer *t)
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*/