These patches are against kernels 2.6.18 through at least 2.6.18-git7.
patch 2: Refactors periodic schedule startup and shutdown code such
that refcounting and code is centralized. Also adds hysteresis such
that shutdown does not occur until there's one full pass through the
periodic schedule with nothing to do.
Signed-off-by: Christopher "Monty" Montgomery <[EMAIL PROTECTED]>
---
diff -X b/Documentation/dontdiff -upr a/drivers/usb/host/ehci.h
b/drivers/usb/host/ehci.h
--- a/drivers/usb/host/ehci.h 2006-09-26 22:12:14.000000000 -0400
+++ b/drivers/usb/host/ehci.h 2006-09-26 22:12:24.000000000 -0400
@@ -479,6 +479,7 @@ struct ehci_iso_stream {
unsigned long rescheduled;
int next_uframe;
__le32 splits;
+ int budget_state;
/* the rest is derived from the endpoint descriptor,
* trusting urb->interval == f(epdesc->bInterval) and
diff -X b/Documentation/dontdiff -upr a/drivers/usb/host/ehci-sched.c
b/drivers/usb/host/ehci-sched.c
--- a/drivers/usb/host/ehci-sched.c 2006-09-26 22:12:14.000000000 -0400
+++ b/drivers/usb/host/ehci-sched.c 2006-09-26 22:12:24.000000000 -0400
@@ -36,6 +36,14 @@
static int ehci_get_frame (struct usb_hcd *hcd);
+/* enable/disable shedule-specific debugging output */
+static unsigned sched_verbose = 0;
+module_param (sched_verbose, uint, S_IRUGO);
+MODULE_PARM_DESC (sched_verbose,
+ "schedule verbose: dump additional scheduling-specific "
+ "debugging information to syslog. Incurs large latencies in"
+ " near-realtime code; default is 0 (off)");
+
/*-------------------------------------------------------------------------*/
/*
@@ -424,51 +432,105 @@ static int tt_no_collision (
#endif /* CONFIG_USB_EHCI_TT_NEWSCHED */
/*-------------------------------------------------------------------------*/
+/* enable_periodic - Activate the periodic schedule
+ *
+ * @ehci: pointer to ehci host controller device structure.
+ */
static int enable_periodic (struct ehci_hcd *ehci)
{
u32 cmd;
int status;
- /* did clearing PSE did take effect yet?
- * takes effect only at frame boundaries...
- */
- status = handshake (&ehci->regs->status, STS_PSS, 0, 9 * 125);
- if (status != 0) {
- ehci_to_hcd(ehci)->state = HC_STATE_HALT;
- return status;
- }
+ if(!ehci->periodic_sched){
+
+ if(sched_verbose)
+ printk(KERN_INFO "ehci: enabling periodic schedule\n");
+
+ /* did clearing PSE did take effect yet?
+ * takes effect only at frame boundaries...
+ */
+ status = handshake (&ehci->regs->status, STS_PSS, 0, 9 * 125);
+ if (status != 0) {
+ ehci_to_hcd(ehci)->state = HC_STATE_HALT;
+ return status;
+ }
+
+ cmd = readl (&ehci->regs->command) | CMD_PSE;
+ writel (cmd, &ehci->regs->command);
+ /* posted write ... PSS happens later */
+ ehci_to_hcd(ehci)->state = HC_STATE_RUNNING;
+
+ /* make sure ehci_work scans these */
+ ehci->next_uframe = readl (&ehci->regs->frame_index)
+ % (ehci->periodic_size << 3);
+ }
+
+ if(ehci->periodic_sched<2)
+ ehci->periodic_sched=2;
+
+ ehci->periodic_sched++;
- cmd = readl (&ehci->regs->command) | CMD_PSE;
- writel (cmd, &ehci->regs->command);
- /* posted write ... PSS happens later */
- ehci_to_hcd(ehci)->state = HC_STATE_RUNNING;
-
- /* make sure ehci_work scans these */
- ehci->next_uframe = readl (&ehci->regs->frame_index)
- % (ehci->periodic_size << 3);
return 0;
}
+/* deref_periodic - decrement refcount of periodic schedule use; will
+ * only take the schedule down to 'idle but running'; it is the
+ * responsibility of scan_periodic to actually halt a running schedule
+ * after it has been idle for one full sweep.
+ *
+ * @ehci: pointer to ehci host controller device structure.
+ */
+static void deref_periodic (struct ehci_hcd *ehci)
+{
+ /* deref as far as 'idle' */
+ if(ehci->periodic_sched>2)
+ ehci->periodic_sched--;
+
+ /* should *never* happen. Watch anyway. */
+ if(ehci->periodic_sched<2){
+ ehci_err(ehci,"periodic schedule refcount incorrect; "
+ "is %d, should be 2. Setting to 2.\n",
+ ehci->periodic_sched);
+ ehci->periodic_sched=2;
+ }
+}
+
+/* disable_periodic - halt execution of the periodic schedule. Note
+ * that the periodic schedule is now disabled after a full pass
+ * through the periodic schedule in which it is unused. It's not
+ * immediately disabled when the last active transfer completes.
+ *
+ * @ehci: pointer to ehci host controller device structure.
+ */
static int disable_periodic (struct ehci_hcd *ehci)
{
u32 cmd;
int status;
+
+ if(ehci->periodic_sched == 1){ /* idle, marked to shutdown */
- /* did setting PSE not take effect yet?
- * takes effect only at frame boundaries...
- */
- status = handshake (&ehci->regs->status, STS_PSS, STS_PSS, 9 * 125);
- if (status != 0) {
- ehci_to_hcd(ehci)->state = HC_STATE_HALT;
- return status;
- }
-
- cmd = readl (&ehci->regs->command) & ~CMD_PSE;
- writel (cmd, &ehci->regs->command);
- /* posted write ... */
+ if(sched_verbose)
+ printk(KERN_INFO "ehci: disabling periodic schedule\n");
- ehci->next_uframe = -1;
+ /* did setting PSE not take effect yet?
+ * takes effect only at frame boundaries...
+ */
+ status = handshake (&ehci->regs->status,
+ STS_PSS, STS_PSS, 9 * 125);
+ if (status != 0) {
+ ehci_to_hcd(ehci)->state = HC_STATE_HALT;
+ return status;
+ }
+
+ cmd = readl (&ehci->regs->command) & ~CMD_PSE;
+ writel (cmd, &ehci->regs->command);
+ /* posted write ... */
+
+ ehci->next_uframe = -1;
+ ehci->periodic_sched = 0; /* shut down */
+ }
+
return 0;
}
@@ -539,10 +601,7 @@ static int qh_link_periodic (struct ehci
: (qh->usecs * 8);
/* maybe enable periodic schedule processing */
- if (!ehci->periodic_sched++)
- return enable_periodic (ehci);
-
- return 0;
+ return enable_periodic (ehci);
}
static void qh_unlink_periodic (struct ehci_hcd *ehci, struct ehci_qh *qh)
@@ -581,9 +640,7 @@ static void qh_unlink_periodic (struct e
qh_put (qh);
/* maybe turn off periodic schedule */
- ehci->periodic_sched--;
- if (!ehci->periodic_sched)
- (void) disable_periodic (ehci);
+ deref_periodic (ehci);
}
static void intr_deschedule (struct ehci_hcd *ehci, struct ehci_qh *qh)
@@ -1008,6 +1065,10 @@ iso_stream_put(struct ehci_hcd *ehci, st
);
}
+ /* potentially shut off periodic schedule */
+ deref_periodic(ehci);
+
+ /* free the stream */
kfree(stream);
}
}
@@ -1340,6 +1401,16 @@ iso_stream_schedule (
goto fail;
}
+ /* first scheduling attempt? */
+ if(!stream->budget_state){
+
+ /* potentially turn on the periodic hardware */
+ status=enable_periodic (ehci);
+ if(status)goto fail;
+
+ stream->budget_state = 1;
+ }
+
now = readl (&ehci->regs->frame_index) % mod;
/* when's the last uframe this urb could start? */
@@ -1547,8 +1618,6 @@ itd_link_urb (
urb->hcpriv = NULL;
timer_action (ehci, TIMER_IO_WATCHDOG);
- if (unlikely (!ehci->periodic_sched++))
- return enable_periodic (ehci);
return 0;
}
@@ -1620,10 +1689,6 @@ itd_complete (
ehci_urb_done (ehci, urb, regs);
urb = NULL;
- /* defer stopping schedule; completion can submit */
- ehci->periodic_sched--;
- if (unlikely (!ehci->periodic_sched))
- (void) disable_periodic (ehci);
ehci_to_hcd(ehci)->self.bandwidth_isoc_reqs--;
if (unlikely (list_empty (&stream->td_list))) {
@@ -1921,8 +1986,6 @@ sitd_link_urb (
urb->hcpriv = NULL;
timer_action (ehci, TIMER_IO_WATCHDOG);
- if (!ehci->periodic_sched++)
- return enable_periodic (ehci);
return 0;
}
@@ -1985,10 +2048,6 @@ sitd_complete (
ehci_urb_done (ehci, urb, regs);
urb = NULL;
- /* defer stopping schedule; completion can submit */
- ehci->periodic_sched--;
- if (!ehci->periodic_sched)
- (void) disable_periodic (ehci);
ehci_to_hcd(ehci)->self.bandwidth_isoc_reqs--;
if (list_empty (&stream->td_list)) {
@@ -2229,6 +2288,25 @@ restart:
} else {
now_uframe++;
now_uframe %= mod;
+
+ if(now_uframe == 0){
+
+ /* if the periodic schedule is still marked
+ to be disabled after a complete pass,
+ disable it now */
+ disable_periodic(ehci);
+
+ /* if the periodic schedule is running
+ but currently empty, do not disable
+ it immediately; that may hurt
+ streaming isoch (as Linux is not
+ using a true periodic schedule).
+ Mark the refcount so that it will
+ be disabled after this pass if no
+ new transactions are enabled */
+ if(ehci->periodic_sched == 2)
+ ehci->periodic_sched = 1;
+ }
}
}
}
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