svn commit: r245132 - head/sys/dev/usb/controller

[Hans Petter Selasky]

Author: hselasky
Date: Mon Jan  7 16:38:13 2013
New Revision: 245132
URL: http://svnweb.freebsd.org/changeset/base/245132

Log:
  Optimise the XHCI interrupt handling.
  This patch will save CPU time when the XHCI interrupt is
  shared with other devices.
  Only check event rings when interrupt bits are set.
  Otherwise would indicate hiding possible hardware fault(s).
  
  Tested by:	sos @
  Submitted by:	sos @
  MFC after:	1 week

Modified:
  head/sys/dev/usb/controller/xhci.c

Modified: head/sys/dev/usb/controller/xhci.c
==============================================================================
--- head/sys/dev/usb/controller/xhci.c	Mon Jan  7 15:46:10 2013	(r245131)
+++ head/sys/dev/usb/controller/xhci.c	Mon Jan  7 16:38:13 2013	(r245132)
@@ -1459,7 +1459,9 @@ xhci_interrupt(struct xhci_softc *sc)
 	DPRINTFN(16, "real interrupt (sts=0x%08x, "
 	    "iman=0x%08x)\n", status, temp);
 
-	if (status != 0) {
+	if (status & (XHCI_STS_PCD | XHCI_STS_HCH |
+	    XHCI_STS_HSE | XHCI_STS_HCE)) {
+
 		if (status & XHCI_STS_PCD) {
 			xhci_root_intr(sc);
 		}
@@ -1480,7 +1482,9 @@ xhci_interrupt(struct xhci_softc *sc)
 		}
 	}
 
-	xhci_interrupt_poll(sc);
+	/* check if we need to check the event rings */
+	if ((status != 0) || (temp & XHCI_IMAN_INTR_PEND))
+		xhci_interrupt_poll(sc);
 
 	USB_BUS_UNLOCK(&sc->sc_bus);
 }