libata: track SLEEP state and issue SRST to wake it up

ATA devices in SLEEP mode don't respond to any commands.  SRST is
necessary to wake it up.  Till now, when a command is issued to a
device in SLEEP mode, the command times out, which makes EH reset the
device and retry the command after that, causing a long delay.

This patch makes libata track SLEEP state and issue SRST automatically
if a command is about to be issued to a device in SLEEP.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Cc: Bruce Allen <ballen@gravity.phys.uwm.edu>
Cc: Andrew Paprocki <andrew@ishiboo.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 5aedd1a..50ae201 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -5630,6 +5630,10 @@
 			ehi->dev_action[dev->devno] |= ATA_EH_REVALIDATE;
 			ata_port_schedule_eh(ap);
 			break;
+
+		case ATA_CMD_SLEEP:
+			dev->flags |= ATA_DFLAG_SLEEPING;
+			break;
 		}
 
 		__ata_qc_complete(qc);
@@ -5769,6 +5773,14 @@
 		qc->flags &= ~ATA_QCFLAG_DMAMAP;
 	}
 
+	/* if device is sleeping, schedule softreset and abort the link */
+	if (unlikely(qc->dev->flags & ATA_DFLAG_SLEEPING)) {
+		link->eh_info.action |= ATA_EH_SOFTRESET;
+		ata_ehi_push_desc(&link->eh_info, "waking up from sleep");
+		ata_link_abort(link);
+		return;
+	}
+
 	ap->ops->qc_prep(qc);
 
 	qc->err_mask |= ap->ops->qc_issue(qc);