libata: skip EH autopsy and recovery during suspend

For some mysterious reason, certain hardware reacts badly to usual EH
actions while the system is going for suspend.  As the devices won't
be needed until the system is resumed, ask EH to skip usual autopsy
and recovery and proceed directly to suspend.

Signed-off-by: Tejun Heo <tj@kernel.org>
Tested-by: Stephan Diestelhorst <stephan.diestelhorst@amd.com>
Cc: stable@kernel.org
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

drivers/ata/libata-core.c

@@ -5418,6 +5418,7 @@ static int ata_host_request_pm(struct ata_host *host, pm_message_t mesg,
  */
 int ata_host_suspend(struct ata_host *host, pm_message_t mesg)
 {
+	unsigned int ehi_flags = ATA_EHI_QUIET;
 	int rc;
 
 	/*
@@ -5426,7 +5427,18 @@ int ata_host_suspend(struct ata_host *host, pm_message_t mesg)
 	 */
 	ata_lpm_enable(host);
 
-	rc = ata_host_request_pm(host, mesg, 0, ATA_EHI_QUIET, 1);
+	/*
+	 * On some hardware, device fails to respond after spun down
+	 * for suspend.  As the device won't be used before being
+	 * resumed, we don't need to touch the device.  Ask EH to skip
+	 * the usual stuff and proceed directly to suspend.
+	 *
+	 * http://thread.gmane.org/gmane.linux.ide/46764
+	 */
+	if (mesg.event == PM_EVENT_SUSPEND)
+		ehi_flags |= ATA_EHI_NO_AUTOPSY | ATA_EHI_NO_RECOVERY;
+
+	rc = ata_host_request_pm(host, mesg, 0, ehi_flags, 1);
 	if (rc == 0)
 		host->dev->power.power_state = mesg;
 	return rc;

drivers/ata/libata-eh.c

@@ -3235,6 +3235,10 @@ static int ata_eh_skip_recovery(struct ata_link *link)
 	if (link->flags & ATA_LFLAG_DISABLED)
 		return 1;
 
+	/* skip if explicitly requested */
+	if (ehc->i.flags & ATA_EHI_NO_RECOVERY)
+		return 1;
+
 	/* thaw frozen port and recover failed devices */
 	if ((ap->pflags & ATA_PFLAG_FROZEN) || ata_link_nr_enabled(link))
 		return 0;

include/linux/libata.h

@@ -335,6 +335,7 @@ enum {
 	ATA_EHI_HOTPLUGGED	= (1 << 0),  /* could have been hotplugged */
 	ATA_EHI_NO_AUTOPSY	= (1 << 2),  /* no autopsy */
 	ATA_EHI_QUIET		= (1 << 3),  /* be quiet */
+	ATA_EHI_NO_RECOVERY	= (1 << 4),  /* no recovery */
 
 	ATA_EHI_DID_SOFTRESET	= (1 << 16), /* already soft-reset this port */
 	ATA_EHI_DID_HARDRESET	= (1 << 17), /* already soft-reset this port */