ide: hook ACPI _PSx method to IDE power on/off

ACPI spec defines the sequence of IDE power on/off:
Powering down:
	Call _GTM.
	Power down drive (calls _PS3 method and turns off power planes).
Powering up:
	Power up drive (calls _PS0 method if present and turns on power planes).
	Call _STM passing info from _GTM (possibly modified), with ID data from
	each drive.
	Initialize the channel.
	May modify the results of _GTF.
	For each drive:
		Call _GTF.
		Execute task file (possibly modified).
This patch adds the missed _PS0/_PS3 methods call.

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Acked-by: Len Brown <len.brown@intel.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/drivers/ide/ide.c b/drivers/ide/ide.c
index de54306..9fdc1fe 100644
--- a/drivers/ide/ide.c
+++ b/drivers/ide/ide.c
@@ -915,6 +915,7 @@
 	struct request rq;
 	struct request_pm_state rqpm;
 	ide_task_t args;
+	int ret;
 
 	/* Call ACPI _GTM only once */
 	if (!(drive->dn % 2))
@@ -931,7 +932,14 @@
 		mesg.event = PM_EVENT_FREEZE;
 	rqpm.pm_state = mesg.event;
 
-	return ide_do_drive_cmd(drive, &rq, ide_wait);
+	ret = ide_do_drive_cmd(drive, &rq, ide_wait);
+	/* only call ACPI _PS3 after both drivers are suspended */
+	if (!ret && (((drive->dn % 2) && hwif->drives[0].present
+		 && hwif->drives[1].present)
+		 || !hwif->drives[0].present
+		 || !hwif->drives[1].present))
+		ide_acpi_set_state(hwif, 0);
+	return ret;
 }
 
 static int generic_ide_resume(struct device *dev)
@@ -944,8 +952,10 @@
 	int err;
 
 	/* Call ACPI _STM only once */
-	if (!(drive->dn % 2))
+	if (!(drive->dn % 2)) {
+		ide_acpi_set_state(hwif, 1);
 		ide_acpi_push_timing(hwif);
+	}
 
 	ide_acpi_exec_tfs(drive);