ChangeSet 1.1234, 2003/06/18 16:48:52-07:00, [EMAIL PROTECTED]
[PATCH] USB: ehci i/o watchdog
This patch adds a new "I/O watchdog" role to the existing
timer code, and cleans it up a bit. If you want to run
EHCI without IRQs, it's now simple: disable them, and
tweak the timer appropriately.
The patch should help with these reported problems.
(a) Bulk I/O sometimes seems to stop progressing. Not
trouble in itself, but usb-storage and scsi could
wedge deeply because of bugs in their fault recovery;
and then the problems could break khubd and rmmod...
(b) Some periodic transfers need to be "jumpstarted".
Usually seen with a high speed hub.
drivers/usb/host/ehci-hcd.c | 24 ++++++++++++--------
drivers/usb/host/ehci-q.c | 35 +++++++++++-------------------
drivers/usb/host/ehci.h | 51 ++++++++++++++++++++++++++++++++++++++++++--
3 files changed, 77 insertions(+), 33 deletions(-)
diff -Nru a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
--- a/drivers/usb/host/ehci-hcd.c Wed Jun 18 17:35:37 2003
+++ b/drivers/usb/host/ehci-hcd.c Wed Jun 18 17:35:37 2003
@@ -118,8 +118,10 @@
#define EHCI_TUNE_MULT_TT 1
#define EHCI_TUNE_FLS 2 /* (small) 256 frame schedule */
-#define EHCI_WATCHDOG_JIFFIES (HZ/100) /* arbitrary; ~10 msec */
+#define EHCI_IAA_JIFFIES (HZ/100) /* arbitrary; ~10 msec */
+#define EHCI_IO_JIFFIES (HZ/10) /* io watchdog > irq_thresh */
#define EHCI_ASYNC_JIFFIES (HZ/20) /* async idle timeout */
+#define EHCI_SHRINK_JIFFIES (HZ/200) /* async qh unlink delay */
/* Initial IRQ latency: lower than default */
static int log2_irq_thresh = 0; // 0 to 6
@@ -268,16 +270,13 @@
}
}
+ /* stop async processing after it's idled a bit */
+ if (test_bit (TIMER_ASYNC_OFF, &ehci->actions))
+ start_unlink_async (ehci, ehci->async);
+
+ /* ehci could run by timer, without IRQs ... */
ehci_work (ehci, NULL);
- if (ehci->reclaim && !timer_pending (&ehci->watchdog))
- mod_timer (&ehci->watchdog,
- jiffies + EHCI_WATCHDOG_JIFFIES);
- /* stop async processing after it's idled a while */
- else if (ehci->async_idle) {
- start_unlink_async (ehci, ehci->async);
- ehci->async_idle = 0;
- }
spin_unlock_irqrestore (&ehci->lock, flags);
}
@@ -660,11 +659,18 @@
*/
static void ehci_work (struct ehci_hcd *ehci, struct pt_regs *regs)
{
+ timer_action_done (ehci, TIMER_IO_WATCHDOG);
if (ehci->reclaim_ready)
end_unlink_async (ehci, regs);
scan_async (ehci, regs);
if (ehci->next_uframe != -1)
scan_periodic (ehci, regs);
+
+ /* the IO watchdog guards against hardware or driver bugs that
+ * misplace IRQs, and should let us run completely without IRQs.
+ */
+ if ((ehci->async->qh_next.ptr != 0) || (ehci->periodic_sched != 0))
+ timer_action (ehci, TIMER_IO_WATCHDOG);
}
/*-------------------------------------------------------------------------*/
diff -Nru a/drivers/usb/host/ehci-q.c b/drivers/usb/host/ehci-q.c
--- a/drivers/usb/host/ehci-q.c Wed Jun 18 17:35:37 2003
+++ b/drivers/usb/host/ehci-q.c Wed Jun 18 17:35:37 2003
@@ -741,8 +741,7 @@
/* (re)start the async schedule? */
head = ehci->async;
- if (ehci->async_idle)
- del_timer (&ehci->watchdog);
+ timer_action_done (ehci, TIMER_ASYNC_OFF);
if (!head->qh_next.qh) {
u32 cmd = readl (&ehci->regs->command);
@@ -773,8 +772,6 @@
qh->qh_state = QH_STATE_LINKED;
/* qtd completions reported later by interrupt */
-
- ehci->async_idle = 0;
}
/*-------------------------------------------------------------------------*/
@@ -955,7 +952,7 @@
struct ehci_qh *qh = ehci->reclaim;
struct ehci_qh *next;
- del_timer (&ehci->watchdog);
+ timer_action_done (ehci, TIMER_IAA_WATCHDOG);
// qh->hw_next = cpu_to_le32 (qh->qh_dma);
qh->qh_state = QH_STATE_IDLE;
@@ -980,12 +977,8 @@
* active but idle for a while once it empties.
*/
if (HCD_IS_RUNNING (ehci->hcd.state)
- && ehci->async->qh_next.qh == 0
- && !timer_pending (&ehci->watchdog)) {
- ehci->async_idle = 1;
- mod_timer (&ehci->watchdog,
- jiffies + EHCI_ASYNC_JIFFIES);
- }
+ && ehci->async->qh_next.qh == 0)
+ timer_action (ehci, TIMER_ASYNC_OFF);
}
if (next)
@@ -1020,6 +1013,7 @@
wmb ();
// handshake later, if we need to
}
+ timer_action_done (ehci, TIMER_ASYNC_OFF);
return;
}
@@ -1045,9 +1039,8 @@
ehci->reclaim_ready = 0;
cmd |= CMD_IAAD;
writel (cmd, &ehci->regs->command);
- /* posted write need not be known to HC yet ... */
-
- mod_timer (&ehci->watchdog, jiffies + EHCI_WATCHDOG_JIFFIES);
+ (void) readl (&ehci->regs->command);
+ timer_action (ehci, TIMER_IAA_WATCHDOG);
}
/*-------------------------------------------------------------------------*/
@@ -1056,10 +1049,11 @@
scan_async (struct ehci_hcd *ehci, struct pt_regs *regs)
{
struct ehci_qh *qh;
- int unlink_delay = 0;
+ enum ehci_timer_action action = TIMER_IO_WATCHDOG;
if (!++(ehci->stamp))
ehci->stamp++;
+ timer_action_done (ehci, TIMER_ASYNC_SHRINK);
rescan:
qh = ehci->async->qh_next.qh;
if (likely (qh != 0)) {
@@ -1091,17 +1085,14 @@
*/
if (list_empty (&qh->qtd_list)) {
if (qh->stamp == ehci->stamp)
- unlink_delay = 1;
- else if (!ehci->reclaim) {
+ action = TIMER_ASYNC_SHRINK;
+ else if (!ehci->reclaim)
start_unlink_async (ehci, qh);
- unlink_delay = 0;
- }
}
qh = qh->qh_next.qh;
} while (qh);
}
-
- if (unlink_delay && !timer_pending (&ehci->watchdog))
- mod_timer (&ehci->watchdog, jiffies + EHCI_WATCHDOG_JIFFIES/2);
+ if (action == TIMER_ASYNC_SHRINK)
+ timer_action (ehci, TIMER_ASYNC_SHRINK);
}
diff -Nru a/drivers/usb/host/ehci.h b/drivers/usb/host/ehci.h
--- a/drivers/usb/host/ehci.h Wed Jun 18 17:35:37 2003
+++ b/drivers/usb/host/ehci.h Wed Jun 18 17:35:37 2003
@@ -52,8 +52,7 @@
/* async schedule support */
struct ehci_qh *async;
struct ehci_qh *reclaim;
- int reclaim_ready : 1,
- async_idle : 1;
+ int reclaim_ready : 1;
/* periodic schedule support */
#define DEFAULT_I_TDPS 1024 /* some HCs can do less */
@@ -83,6 +82,7 @@
struct timer_list watchdog;
struct notifier_block reboot_notifier;
+ unsigned long actions;
unsigned stamp;
/* irq statistics */
@@ -99,6 +99,53 @@
/* NOTE: urb->transfer_flags expected to not use this bit !!! */
#define EHCI_STATE_UNLINK 0x8000 /* urb being unlinked */
+
+enum ehci_timer_action {
+ TIMER_IO_WATCHDOG,
+ TIMER_IAA_WATCHDOG,
+ TIMER_ASYNC_SHRINK,
+ TIMER_ASYNC_OFF,
+};
+
+static inline void
+timer_action_done (struct ehci_hcd *ehci, enum ehci_timer_action action)
+{
+ clear_bit (action, &ehci->actions);
+}
+
+static inline void
+timer_action (struct ehci_hcd *ehci, enum ehci_timer_action action)
+{
+ if (!test_and_set_bit (action, &ehci->actions)) {
+ unsigned long t;
+
+ switch (action) {
+ case TIMER_IAA_WATCHDOG:
+ t = EHCI_IAA_JIFFIES;
+ break;
+ case TIMER_IO_WATCHDOG:
+ t = EHCI_IO_JIFFIES;
+ break;
+ case TIMER_ASYNC_OFF:
+ t = EHCI_ASYNC_JIFFIES;
+ break;
+ // case TIMER_ASYNC_SHRINK:
+ default:
+ t = EHCI_SHRINK_JIFFIES;
+ break;
+ }
+ t += jiffies;
+ // all timings except IAA watchdog can be overridden.
+ // async queue SHRINK often precedes IAA. while it's ready
+ // to go OFF neither can matter, and afterwards the IO
+ // watchdog stops unless there's still periodic traffic.
+ if (action != TIMER_IAA_WATCHDOG
+ && t > ehci->watchdog.expires
+ && timer_pending (&ehci->watchdog))
+ return;
+ mod_timer (&ehci->watchdog, t);
+ }
+}
/*-------------------------------------------------------------------------*/
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