[PATCH] ehci-hcd (2/2): rest of tasklet remove

This is the rest of the work to remove the tasklet: the non-syntax
portions which affect work scheduling.  It's not quite davem's version;
it's got locking updates, which among other things prevent a hang when
the timer kicks in.

This scheduling change is split out from the other parts in case more
problems like that unlink race (fixed in my previous patch) show up.
It doesn't fix (or help fix) any ehci bugs, but simpler code is fine.

drivers/usb/host/ehci-hcd.c

@@ -244,9 +244,7 @@ static void ehci_ready (struct ehci_hcd *ehci)
 
 /*-------------------------------------------------------------------------*/
 
-static void ehci_tasklet (unsigned long param);
-
-static void ehci_irq (struct usb_hcd *hcd, struct pt_regs *regs);
+static void ehci_work(struct ehci_hcd *ehci, struct pt_regs *regs);
 
 static void ehci_watchdog (unsigned long param)
 {
@@ -254,10 +252,25 @@ static void ehci_watchdog (unsigned long param)
 	unsigned long		flags;
 
 	spin_lock_irqsave (&ehci->lock, flags);
-	/* guard against lost IAA, which wedges everything */
-	ehci_irq (&ehci->hcd, NULL);
+
+	/* lost IAA irqs wedge things badly; seen with a vt8235 */
+	if (ehci->reclaim) {
+		u32		status = readl (&ehci->regs->status);
+
+		if (status & STS_IAA) {
+			ehci_vdbg (ehci, "lost IAA\n");
+			writel (STS_IAA, &ehci->regs->status);
+			ehci->reclaim_ready = 1;
+		}
+	}
+
+	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 */
- 	if (ehci->async_idle) {
+	else if (ehci->async_idle) {
  		start_unlink_async (ehci, ehci->async);
  		ehci->async_idle = 0;
 	}
@@ -418,9 +431,6 @@ static int ehci_start (struct usb_hcd *hcd)
 
 	/* set async sleep time = 10 us ... ? */
 
-	ehci->tasklet.func = ehci_tasklet;
-	ehci->tasklet.data = (unsigned long) ehci;
-
 	init_timer (&ehci->watchdog);
 	ehci->watchdog.function = ehci_watchdog;
 	ehci->watchdog.data = (unsigned long) ehci;
@@ -499,8 +509,9 @@ static void ehci_stop (struct usb_hcd *hcd)
 	remove_debug_files (ehci);
 
 	/* root hub is shut down separately (first, when possible) */
-	tasklet_disable (&ehci->tasklet);
-	ehci_tasklet ((unsigned long) ehci);
+	spin_lock_irq (&ehci->lock);
+	ehci_work (ehci, NULL);
+	spin_unlock_irq (&ehci->lock);
 	ehci_mem_cleanup (ehci);
 
 #ifdef	EHCI_STATS
@@ -608,23 +619,16 @@ dbg ("%s: resume port %d", hcd_to_bus (hcd)->bus_name, i);
 /*-------------------------------------------------------------------------*/
 
 /*
- * tasklet scheduled by some interrupts and other events
- * calls driver completion functions ... but not in_irq()
+ * ehci_work is called from some interrupts, timers, and so on.
+ * it calls driver completion functions, after dropping ehci->lock.
  */
-static void ehci_tasklet (unsigned long param)
+static void ehci_work (struct ehci_hcd *ehci, struct pt_regs *regs)
 {
-	struct ehci_hcd		*ehci = (struct ehci_hcd *) param;
-	struct pt_regs		*regs = NULL;
-
-	spin_lock_irq (&ehci->lock);
-
 	if (ehci->reclaim_ready)
 		end_unlink_async (ehci, regs);
 	scan_async (ehci, regs);
 	if (ehci->next_uframe != -1)
 		scan_periodic (ehci, regs);
-
-	spin_unlock_irq (&ehci->lock);
 }
 
 /*-------------------------------------------------------------------------*/
@@ -645,6 +649,8 @@ static void ehci_irq (struct usb_hcd *hcd, struct pt_regs *regs)
 	if (!status)			/* irq sharing? */
 		return;
 
+	spin_lock (&ehci->lock);
+
 	/* clear (just) interrupts */
 	writel (status, &ehci->regs->status);
 	readl (&ehci->regs->command);	/* unblock posted write */
@@ -684,9 +690,9 @@ static void ehci_irq (struct usb_hcd *hcd, struct pt_regs *regs)
 		bh = 1;
 	}
 
-	/* most work doesn't need to be in_irq() */
-	if (likely (bh == 1))
-		tasklet_schedule (&ehci->tasklet);
+	if (bh)
+		ehci_work (ehci, regs);
+	spin_unlock (&ehci->lock);
 }
 
 /*-------------------------------------------------------------------------*/
@@ -882,7 +888,7 @@ static void ehci_free_config (struct usb_hcd *hcd, struct usb_device *udev)
 					) {
 				spin_unlock_irqrestore (&ehci->lock, flags);
 				/* wait_ms() won't spin, we're a thread;
-				 * and we know IRQ+tasklet can progress
+				 * and we know IRQ/timer/... can progress
 				 */
 				wait_ms (1);
 				spin_lock_irqsave (&ehci->lock, flags);

drivers/usb/host/ehci-sched.c

@@ -190,7 +190,7 @@ static int enable_periodic (struct ehci_hcd *ehci)
 	/* posted write ... PSS happens later */
 	ehci->hcd.state = USB_STATE_RUNNING;
 
-	/* make sure tasklet scans these */
+	/* make sure ehci_work scans these */
 	ehci->next_uframe = readl (&ehci->regs->frame_index)
 				% (ehci->periodic_size << 3);
 	return 0;

drivers/usb/host/ehci.h

@@ -65,9 +65,6 @@ struct ehci_hcd {			/* one per controller */
 	int			next_uframe;	/* scan periodic, start here */
 	unsigned		periodic_sched;	/* periodic activity count */
 
-	/* deferred work from IRQ, etc */
-	struct tasklet_struct	tasklet;
-
 	/* per root hub port */
 	unsigned long		reset_done [EHCI_MAX_ROOT_PORTS];