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-hcd.c b/drivers/usb/host/ehci-hcd.c
index baf9b64..8697ad1 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -584,6 +584,11 @@
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 @@
/* 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 @@
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;