USB: EHCI: EHCI 1.1 addendum: Enable Per-port change detect bits
This patch will enable Per-port event feature defined in EHCI 1.1
addendum. This feature addresses an issue where HCD is currently
required to read and parse PORTSC for all enabled root hub ports. With
this patch, the overhead will be reduced.
Signed-off-by: Alek Du <alek.du@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/host/ehci-hub.c b/drivers/usb/host/ehci-hub.c
index 8a28dae..84e792d 100644
--- a/drivers/usb/host/ehci-hub.c
+++ b/drivers/usb/host/ehci-hub.c
@@ -603,6 +603,7 @@
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 @@
/* 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]);
/*