diff --git a/drivers/usb/host/ehci-dbg.c b/drivers/usb/host/ehci-dbg.c
index 9952505d..d6d74d2 100644
--- a/drivers/usb/host/ehci-dbg.c
+++ b/drivers/usb/host/ehci-dbg.c
@@ -821,7 +821,7 @@
 	next += temp;
 
 	temp = scnprintf (next, size, "uframe %04x\n",
-			ehci_readl(ehci, &ehci->regs->frame_index));
+			ehci_read_frame_index(ehci));
 	size -= temp;
 	next += temp;
 
diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index 05abbcd..59e8161 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -1195,8 +1195,7 @@
 static int ehci_get_frame (struct usb_hcd *hcd)
 {
 	struct ehci_hcd		*ehci = hcd_to_ehci (hcd);
-	return (ehci_readl(ehci, &ehci->regs->frame_index) >> 3) %
-		ehci->periodic_size;
+	return (ehci_read_frame_index(ehci) >> 3) % ehci->periodic_size;
 }
 
 /*-------------------------------------------------------------------------*/
diff --git a/drivers/usb/host/ehci-pci.c b/drivers/usb/host/ehci-pci.c
index 8311de7..f4b627d 100644
--- a/drivers/usb/host/ehci-pci.c
+++ b/drivers/usb/host/ehci-pci.c
@@ -224,6 +224,11 @@
 			pci_dev_put(p_smbus);
 		}
 		break;
+	case PCI_VENDOR_ID_NETMOS:
+		/* MosChip frame-index-register bug */
+		ehci_info(ehci, "applying MosChip frame-index workaround\n");
+		ehci->frame_index_bug = 1;
+		break;
 	}
 
 	/* optional debug port, normally in the first BAR */
diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c
index 488151b..2e829fa 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 @@
 	/* 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 @@
 		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 @@
 	 */
 	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 @@
 					|| 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;
 
diff --git a/drivers/usb/host/ehci.h b/drivers/usb/host/ehci.h
index c161d97..0a5fda7 100644
--- a/drivers/usb/host/ehci.h
+++ b/drivers/usb/host/ehci.h
@@ -146,6 +146,7 @@
 	unsigned		fs_i_thresh:1;	/* Intel iso scheduling */
 	unsigned		use_dummy_qh:1;	/* AMD Frame List table quirk*/
 	unsigned		has_synopsys_hc_bug:1; /* Synopsys HC */
+	unsigned		frame_index_bug:1; /* MosChip (AKA NetMos) */
 
 	/* required for usb32 quirk */
 	#define OHCI_CTRL_HCFS          (3 << 6)
@@ -747,6 +748,22 @@
 
 /*-------------------------------------------------------------------------*/
 
+#ifdef CONFIG_PCI
+
+/* For working around the MosChip frame-index-register bug */
+static unsigned ehci_read_frame_index(struct ehci_hcd *ehci);
+
+#else
+
+static inline unsigned ehci_read_frame_index(struct ehci_hcd *ehci)
+{
+	return ehci_readl(ehci, &ehci->regs->frame_index);
+}
+
+#endif
+
+/*-------------------------------------------------------------------------*/
+
 #ifndef DEBUG
 #define STUB_DEBUG_FILES
 #endif	/* DEBUG */