Fixes for some recent OHCI instability.

    - Never munge ed->hwTailP once it's set up, except when appending
      to the queue.

    - Don't clear control/bulk "current ED" registers when taking
      entries off the queue.  The chip may still be using the value.

    - Revert part of previous bk1 patch, which removed a fast path
      that makes a visible difference in some common operations.
      Removing it just slowed timings, and didn't fix anything.

    - Make the "unlink during submit" path behave better (SMP).


--- 1.50/drivers/usb/host/ohci-q.c	Tue Mar  2 22:48:07 2004
+++ edited/drivers/usb/host/ohci-q.c	Mon Mar  8 13:15:08 2004
@@ -282,7 +282,6 @@
 			if (!ed->hwNextED) {
 				ohci->hc_control &= ~OHCI_CTRL_CLE;
 				writel (ohci->hc_control, &ohci->regs->control);
-				writel (0, &ohci->regs->ed_controlcurrent);
 				// post those pci writes
 				(void) readl (&ohci->regs->control);
 			}
@@ -306,7 +305,6 @@
 			if (!ed->hwNextED) {
 				ohci->hc_control &= ~OHCI_CTRL_BLE;
 				writel (ohci->hc_control, &ohci->regs->control);
-				writel (0, &ohci->regs->ed_bulkcurrent);
 				// post those pci writes
 				(void) readl (&ohci->regs->control);
 			}
@@ -331,6 +329,19 @@
 		periodic_unlink (ohci, ed);
 		break;
 	}
+
+	/* NOTE: Except for a couple of exceptionally clean unlink cases
+	 * (like unlinking the only c/b ED, with no TDs) HCs may still be
+	 * caching this operational ED (or its address).  Safe unlinking
+	 * involves not marking it ED_IDLE till INTR_SF; we always do that
+	 * if td_list isn't empty.  Otherwise the race is small; but ...
+	 */
+	if (ed->state == ED_OPER) {
+		ed->state = ED_IDLE;
+		ed->hwINFO &= ~(ED_SKIP | ED_DEQUEUE);
+		ed->hwHeadP &= ~ED_H;
+		wmb ();
+	}
 }
 
 
@@ -794,8 +805,6 @@
 		next->next_dl_td = rev;	
 		rev = next;
 
-		if (ed->hwTailP == cpu_to_le32 (next->td_dma))
-			ed->hwTailP = next->hwNextTD;
 		ed->hwHeadP = next->hwNextTD | toggle;
 	}
 
@@ -941,12 +950,7 @@
 				continue;
 			}
 
-			/* patch pointers hc uses ... tail, if we're removing
-			 * an otherwise active td, and whatever td pointer
-			 * points to this td
-			 */
-			if (ed->hwTailP == cpu_to_le32 (td->td_dma))
-				ed->hwTailP = td->hwNextTD;
+			/* patch pointer hc uses */
 			savebits = *prev & ~cpu_to_le32 (TD_MASK);
 			*prev = td->hwNextTD | savebits;
 
@@ -1041,7 +1045,7 @@
 
 		/* clean schedule:  unlink EDs that are no longer busy */
 		if (list_empty (&ed->td_list))
-			start_ed_unlink (ohci, ed);
+			ed_deschedule (ohci, ed);
 		/* ... reenabling halted EDs only after fault cleanup */
 		else if ((ed->hwINFO & (ED_SKIP | ED_DEQUEUE)) == ED_SKIP) {
 			td = list_entry (ed->td_list.next, struct td, td_list);
--- 1.57/drivers/usb/host/ohci-hcd.c	Tue Mar  2 22:48:07 2004
+++ edited/drivers/usb/host/ohci-hcd.c	Mon Mar  8 12:39:24 2004
@@ -233,7 +233,7 @@
 	spin_lock (&urb->lock);
 	if (urb->status != -EINPROGRESS) {
 		spin_unlock (&urb->lock);
-
+		urb->hcpriv = urb_priv;
 		finish_urb (ohci, urb, 0);
 		retval = 0;
 		goto fail;