1 files changed, 25 insertions, 5 deletions

diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c
index 488151bb45cb..2e829fae6482 100644
--- a/drivers/usb/host/ehci-sched.c
+++ b/drivers/usb/host/ehci-sched.c
@@ -36,6 +36,27 @@
 
 static int ehci_get_frame (struct usb_hcd *hcd);
 
+#ifdef CONFIG_PCI
+
+static unsigned ehci_read_frame_index(struct ehci_hcd *ehci)
+{
+	unsigned uf;
+
+	/*
+	 * The MosChip MCS9990 controller updates its microframe counter
+	 * a little before the frame counter, and occasionally we will read
+	 * the invalid intermediate value.  Avoid problems by checking the
+	 * microframe number (the low-order 3 bits); if they are 0 then
+	 * re-read the register to get the correct value.
+	 */
+	uf = ehci_readl(ehci, &ehci->regs->frame_index);
+	if (unlikely(ehci->frame_index_bug && ((uf & 7) == 0)))
+		uf = ehci_readl(ehci, &ehci->regs->frame_index);
+	return uf;
+}
+
+#endif
+
 /*-------------------------------------------------------------------------*/
 
 /*
@@ -481,7 +502,7 @@ static int enable_periodic (struct ehci_hcd *ehci)
 	/* posted write ... PSS happens later */
 
 	/* make sure ehci_work scans these */
-	ehci->next_uframe = ehci_readl(ehci, &ehci->regs->frame_index)
+	ehci->next_uframe = ehci_read_frame_index(ehci)
 		% (ehci->periodic_size << 3);
 	if (unlikely(ehci->broken_periodic))
 		ehci->last_periodic_enable = ktime_get_real();
@@ -1408,7 +1429,7 @@ iso_stream_schedule (
 		goto fail;
 	}
 
-	now = ehci_readl(ehci, &ehci->regs->frame_index) & (mod - 1);
+	now = ehci_read_frame_index(ehci) & (mod - 1);
 
 	/* Typical case: reuse current schedule, stream is still active.
 	 * Hopefully there are no gaps from the host falling behind
@@ -2275,7 +2296,7 @@ scan_periodic (struct ehci_hcd *ehci)
 	 */
 	now_uframe = ehci->next_uframe;
 	if (ehci->rh_state == EHCI_RH_RUNNING) {
-		clock = ehci_readl(ehci, &ehci->regs->frame_index);
+		clock = ehci_read_frame_index(ehci);
 		clock_frame = (clock >> 3) & (ehci->periodic_size - 1);
 	} else  {
 		clock = now_uframe + mod - 1;
@@ -2454,8 +2475,7 @@ restart:
 					|| ehci->periodic_sched == 0)
 				break;
 			ehci->next_uframe = now_uframe;
-			now = ehci_readl(ehci, &ehci->regs->frame_index) &
-					(mod - 1);
+			now = ehci_read_frame_index(ehci) & (mod - 1);
 			if (now_uframe == now)
 				break;