xhci: Return canceled URBs immediately when host is halted.

When the xHCI host controller is halted, it won't respond to commands
placed on the command ring. So if an URB is cancelled after the first
roothub is deallocated, it will try to place a stop endpoint command on
the command ring, which will fail. The command watchdog timer will fire
after five seconds, and the host controller will be marked as dying, and
all URBs will be completed.

Add a flag to the xHCI's internal state variable for when the host
controller is halted. Immediately return the canceled URB if the host
controller is halted.

Signed-off-by: Sarah Sharp <[e-mail]>

drivers/usb/host/xhci.c

···
  */
 int xhci_halt(struct xhci_hcd *xhci)
 {
+	int ret;
 	xhci_dbg(xhci, "// Halt the HC\n");
 	xhci_quiesce(xhci);
 
-	return handshake(xhci, &xhci->op_regs->status,
+	ret = handshake(xhci, &xhci->op_regs->status,
 			STS_HALT, STS_HALT, XHCI_MAX_HALT_USEC);
+	if (!ret)
+		xhci->xhc_state |= XHCI_STATE_HALTED;
+	return ret;
 }
 
 /*
···
 		xhci_err(xhci, "Host took too long to start, "
 				"waited %u microseconds.\n",
 				XHCI_MAX_HALT_USEC);
+	if (!ret)
+		xhci->xhc_state &= ~XHCI_STATE_HALTED;
 	return ret;
 }
 
···
 	if (ret || !urb->hcpriv)
 		goto done;
 	temp = xhci_readl(xhci, &xhci->op_regs->status);
-	if (temp == 0xffffffff) {
+	if (temp == 0xffffffff || (xhci->xhc_state & XHCI_STATE_HALTED)) {
 		xhci_dbg(xhci, "HW died, freeing TD.\n");
 		urb_priv = urb->hcpriv;
 

drivers/usb/host/xhci.h

···
  * There are no reports of xHCI host controllers that display this issue.
  */
 #define XHCI_STATE_DYING	(1 << 0)
+#define XHCI_STATE_HALTED	(1 << 1)
 	/* Statistics */
 	int			error_bitmask;
 	unsigned int		quirks;