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@xxxxxxxxxxxxxxxxxxx>
---
drivers/usb/host/ehci-hcd.c | 20 ++++++++++----------
drivers/usb/host/ehci-timer.c | 26 ++++++++++++++++++++++++++
drivers/usb/host/ehci.h | 2 ++
3 files changed, 38 insertions(+), 10 deletions(-)
Index: usb-3.4/drivers/usb/host/ehci.h
===================================================================
--- usb-3.4.orig/drivers/usb/host/ehci.h
+++ usb-3.4/drivers/usb/host/ehci.h
@@ -81,6 +81,7 @@ enum ehci_rh_state {
enum ehci_hrtimer_event {
EHCI_HRTIMER_POLL_ASS, /* Poll for async schedule off */
EHCI_HRTIMER_POLL_PSS, /* Poll for periodic schedule off */
+ EHCI_HRTIMER_POLL_DEAD, /* Wait for dead controller to stop */
EHCI_HRTIMER_UNLINK_INTR, /* Wait for interrupt QH unlink */
EHCI_HRTIMER_DISABLE_PERIODIC, /* Wait to disable periodic sched */
EHCI_HRTIMER_DISABLE_ASYNC, /* Wait to disable async sched */
@@ -97,6 +98,7 @@ struct ehci_hcd { /* one per controlle
int PSS_poll_count;
int ASS_poll_count;
+ int died_poll_count;
/* glue to PCI and HCD framework */
struct ehci_caps __iomem *caps;
Index: usb-3.4/drivers/usb/host/ehci-hcd.c
===================================================================
--- usb-3.4.orig/drivers/usb/host/ehci-hcd.c
+++ usb-3.4/drivers/usb/host/ehci-hcd.c
@@ -888,20 +888,20 @@ static irqreturn_t ehci_irq (struct usb_
/* PCI errors [4.15.2.4] */
if (unlikely ((status & STS_FATAL) != 0)) {
ehci_err(ehci, "fatal error\n");
- ehci->rh_state = EHCI_RH_STOPPING;
dbg_cmd(ehci, "fatal", cmd);
dbg_status(ehci, "fatal", status);
- ehci_halt(ehci);
dead:
- ehci->enabled_hrtimer_events = 0;
- hrtimer_try_to_cancel(&ehci->hrtimer);
- ehci_reset(ehci);
- ehci_writel(ehci, 0, &ehci->regs->configured_flag);
usb_hc_died(hcd);
- /* generic layer kills/unlinks all urbs, then
- * uses ehci_stop to clean up the rest
- */
- bh = 1;
+
+ /* Don't let the controller do anything more */
+ ehci->rh_state = EHCI_RH_STOPPING;
+ ehci->command &= ~(CMD_RUN | CMD_ASE | CMD_PSE);
+ ehci_writel(ehci, ehci->command, &ehci->regs->command);
+ ehci_writel(ehci, 0, &ehci->regs->intr_enable);
+ ehci_handle_controller_death(ehci);
+
+ /* Handle completions when the controller stops */
+ bh = 0;
}
if (bh)
Index: usb-3.4/drivers/usb/host/ehci-timer.c
===================================================================
--- usb-3.4.orig/drivers/usb/host/ehci-timer.c
+++ usb-3.4/drivers/usb/host/ehci-timer.c
@@ -69,6 +69,7 @@ static void ehci_clear_command_bit(struc
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
}
+/* 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(str
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 */
--
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