svn commit: r249852 - stable/9/sys/dev/ahci

[Alexander Motin]

Author: mav
Date: Wed Apr 24 19:33:37 2013
New Revision: 249852
URL: http://svnweb.freebsd.org/changeset/base/249852

Log:
  MFC r248704:
  Read Asynchronous Notification statuses only if Port Multiplier or ATAPI
  device are connected. ATA disks are not using ANs, while the extra register
  read operation is quite expensive.

Modified:
  stable/9/sys/dev/ahci/ahci.c
Directory Properties:
  stable/9/sys/   (props changed)
  stable/9/sys/dev/   (props changed)

Modified: stable/9/sys/dev/ahci/ahci.c
==============================================================================
--- stable/9/sys/dev/ahci/ahci.c	Wed Apr 24 19:24:53 2013	(r249851)
+++ stable/9/sys/dev/ahci/ahci.c	Wed Apr 24 19:33:37 2013	(r249852)
@@ -1524,7 +1524,8 @@ ahci_ch_intr(void *data)
 	if (ch->numrslots != ch->numtslots)
 		cstatus |= ATA_INL(ch->r_mem, AHCI_P_CI);
 	/* Read SNTF in one of possible ways. */
-	if (istatus & AHCI_P_IX_SDB) {
+	if ((istatus & AHCI_P_IX_SDB) &&
+	    (ch->pm_present || ch->curr[0].atapi != 0)) {
 		if (ch->caps & AHCI_CAP_SSNTF)
 			sntf = ATA_INL(ch->r_mem, AHCI_P_SNTF);
 		else if (ch->fbs_enabled) {