[PATCH] usb problems (ohci-hcd + printer)

This fixes a number of issues in OHCI:

 - Force out the PCI write disabling control/bulk queues.
   This "shouldn't" matter, they're empty.

 - The rule is that if an ED is IDLE, its OK to just
   schedule it and start appending TDs.  Hard to do that
   when the typical error path left them still halted!

 - Sometimes ed->hwTailP needs updating when TDs are
   removed from the queue, not just ed->hwHeadP. Oops.

 - Oh, and it's not the high bits we want to save when
   we unlink ... it's the low bits (actually just toggle).

Except for forcing the writes to the controller, these patches should
only affect (improve :) fault and unlink handling.

drivers/usb/host/ohci-q.c

@@ -265,6 +265,9 @@ static void ed_deschedule (struct ohci_hcd *ohci, struct ed *ed)
 			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);
 			}
 			writel (le32_to_cpup (&ed->hwNextED),
 				&ohci->regs->ed_controlhead);
@@ -286,6 +289,9 @@ static void ed_deschedule (struct ohci_hcd *ohci, struct ed *ed)
 			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);
 			}
 			writel (le32_to_cpup (&ed->hwNextED),
 				&ohci->regs->ed_bulkhead);
@@ -315,8 +321,12 @@ static void ed_deschedule (struct ohci_hcd *ohci, struct ed *ed)
 	 * 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)
+	if (ed->state == ED_OPER) {
 		ed->state = ED_IDLE;
+		ed->hwINFO &= ~(ED_SKIP | ED_DEQUEUE);
+		ed->hwHeadP &= ~ED_H;
+		wmb ();
+	}
 }
 
 
@@ -767,6 +777,8 @@ ed_halted (struct ohci_hcd *ohci, struct td *td, int cc, struct td *rev)
 		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;
 	}
 
@@ -881,8 +893,13 @@ static void finish_unlinks (struct ohci_hcd *ohci, u16 tick)
 				continue;
 			}
 
-			/* patch pointer hc uses */
-			savebits = *prev & cpu_to_le32 (TD_MASK);
+			/* 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;
+			savebits = *prev & ~cpu_to_le32 (TD_MASK);
 			*prev = td->hwNextTD | savebits;
 
 			/* HC may have partly processed this TD */