libata: force hardreset if link is in powersave mode

[Tejun Heo <htejun@gmail.com>]

Inhibiting link PM mode doesn't bring the link back online if it's
already in powersave mode.  If SRST is used in these cases, libata EH
thinks that the link is offline and fails detection.  Force hardreset
if link is in powersave mode.

Signed-off-by: Tejun Heo <htejun@gmail.com>
---
Patch for -stable only.  Devel branch now uses hardreset by default so
this type of promotion logic isn't necessary anymore.

 drivers/ata/libata-core.c |   12 ++++++++++++
 1 file changed, 12 insertions(+)

Index: linux-2.6.25/drivers/ata/libata-core.c
===================================================================
--- linux-2.6.25.orig/drivers/ata/libata-core.c
+++ linux-2.6.25/drivers/ata/libata-core.c
@@ -3960,6 +3960,7 @@ int ata_std_prereset(struct ata_link *li
 	struct ata_port *ap = link->ap;
 	struct ata_eh_context *ehc = &link->eh_context;
 	const unsigned long *timing = sata_ehc_deb_timing(ehc);
+	u32 sstatus;
 	int rc;
 
 	/* handle link resume */
@@ -3973,6 +3974,17 @@ int ata_std_prereset(struct ata_link *li
 	if (ap->flags & ATA_FLAG_PMP)
 		ehc->i.action |= ATA_EH_HARDRESET;
 
+	/* if link powersave is on, force hardreset */
+	if (sata_scr_read(link, SCR_STATUS, &sstatus) == 0) {
+		u8 ipm = sstatus >> 8;
+
+		if (ipm == 2 || ipm == 6) {
+			ata_link_printk(link, KERN_INFO, "link in powersave "
+				"mode (ipm=%d), forcing hardreset\n", ipm);
+			ehc->i.action |= ATA_EH_HARDRESET;
+		}
+	}
+
 	/* if we're about to do hardreset, nothing more to do */
 	if (ehc->i.action & ATA_EH_HARDRESET)
 		return 0;