3 files changed, 27 insertions, 2 deletions

diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index baf9b648bb1f..8697ad19f313 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -584,6 +584,11 @@ static int ehci_init(struct usb_hcd *hcd)
         if (log2_irq_thresh < 0 || log2_irq_thresh > 6)
                 log2_irq_thresh = 0;
         temp = 1 << (16 + log2_irq_thresh);
+        if (HCC_PER_PORT_CHANGE_EVENT(hcc_params)) {
+                ehci->has_ppcd = 1;
+                ehci_dbg(ehci, "enable per-port change event\n");
+                temp |= CMD_PPCEE;
+        }
         if (HCC_CANPARK(hcc_params)) {
                 /* HW default park == 3, on hardware that supports it (like
                  * NVidia and ALI silicon), maximizes throughput on the async
@@ -782,6 +787,7 @@ static irqreturn_t ehci_irq (struct usb_hcd *hcd)
         /* remote wakeup [4.3.1] */
         if (status & STS_PCD) {
                 unsigned        i = HCS_N_PORTS (ehci->hcs_params);
+                u32             ppcd = 0;
 
                 /* kick root hub later */
                 pcd_status = status;
@@ -790,9 +796,18 @@ static irqreturn_t ehci_irq (struct usb_hcd *hcd)
                 if (!(cmd & CMD_RUN))
                         usb_hcd_resume_root_hub(hcd);
 
+                /* get per-port change detect bits */
+                if (ehci->has_ppcd)
+                        ppcd = status >> 16;
+
                 while (i--) {
-                        int pstatus = ehci_readl(ehci,
-                                                 &ehci->regs->port_status [i]);
+                        int pstatus;
+
+                        /* leverage per-port change bits feature */
+                        if (ehci->has_ppcd && !(ppcd & (1 << i)))
+                                continue;
+                        pstatus = ehci_readl(ehci,
+                                         &ehci->regs->port_status[i]);
 
                         if (pstatus & PORT_OWNER)
                                 continue;
diff --git a/drivers/usb/host/ehci-hub.c b/drivers/usb/host/ehci-hub.c
index 8a28dae8a375..84e792d71c22 100644
--- a/drivers/usb/host/ehci-hub.c
+++ b/drivers/usb/host/ehci-hub.c
@@ -603,6 +603,7 @@ ehci_hub_status_data (struct usb_hcd *hcd, char *buf)
         u32             mask;
         int             ports, i, retval = 1;
         unsigned long   flags;
+        u32             ppcd = 0;
 
         /* if !USB_SUSPEND, root hub timers won't get shut down ... */
         if (!HC_IS_RUNNING(hcd->state))
@@ -632,7 +633,15 @@ ehci_hub_status_data (struct usb_hcd *hcd, char *buf)
 
         /* port N changes (bit N)? */
         spin_lock_irqsave (&ehci->lock, flags);
+
+        /* get per-port change detect bits */
+        if (ehci->has_ppcd)
+                ppcd = ehci_readl(ehci, &ehci->regs->status) >> 16;
+
         for (i = 0; i < ports; i++) {
+                /* leverage per-port change bits feature */
+                if (ehci->has_ppcd && !(ppcd & (1 << i)))
+                        continue;
                 temp = ehci_readl(ehci, &ehci->regs->port_status [i]);
 
                 /*
diff --git a/drivers/usb/host/ehci.h b/drivers/usb/host/ehci.h
index 21f30a0c3d2f..e6c57cc416f6 100644
--- a/drivers/usb/host/ehci.h
+++ b/drivers/usb/host/ehci.h
@@ -141,6 +141,7 @@ struct ehci_hcd {			/* one per controller */
         __hc32                  *ohci_hcctrl_reg;
         unsigned                has_hostpc:1;
         unsigned                has_lpm:1;  /* support link power management */
+        unsigned                has_ppcd:1; /* support per-port change bits */
         u8                      sbrn;           /* packed release number */
 
         /* irq statistics */