ata: libata-core: Do not register PM operations for SAS ports

libsas does its own domain based power management of ports. For such
ports, libata should not use a device type defining power management
operations as executing these operations for suspend/resume in addition
to libsas calls to ata_sas_port_suspend() and ata_sas_port_resume() is
not necessary (and likely dangerous to do, even though problems are not
seen currently).

Introduce the new ata_port_sas_type device_type for ports managed by
libsas. This new device type is used in ata_tport_add() and is defined
without power management operations.

Fixes: 2fcbdcb ("[SCSI] libata: export ata_port suspend/resume infrastructure for sas")
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Tested-by: Chia-Lin Kao (AceLan) <acelan.kao@canonical.com>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>

Author: damien-lemoal

drivers/ata/libata-core.c

@@ -5335,7 +5335,7 @@ EXPORT_SYMBOL_GPL(ata_host_resume);
 #endif
 
 const struct device_type ata_port_type = {
-	.name = "ata_port",
+	.name = ATA_PORT_TYPE_NAME,
 #ifdef CONFIG_PM
 	.pm = &ata_port_pm_ops,
 #endif

drivers/ata/libata-transport.c

@@ -266,6 +266,10 @@ void ata_tport_delete(struct ata_port *ap)
 	put_device(dev);
 }
 
+static const struct device_type ata_port_sas_type = {
+	.name = ATA_PORT_TYPE_NAME,
+};
+
 /** ata_tport_add - initialize a transport ATA port structure
  *
  * @parent:	parent device
@@ -283,7 +287,10 @@ int ata_tport_add(struct device *parent,
 	struct device *dev = &ap->tdev;
 
 	device_initialize(dev);
-	dev->type = &ata_port_type;
+	if (ap->flags & ATA_FLAG_SAS_HOST)
+		dev->type = &ata_port_sas_type;
+	else
+		dev->type = &ata_port_type;
 
 	dev->parent = parent;
 	ata_host_get(ap->host);

drivers/ata/libata.h

@@ -30,6 +30,8 @@ enum {
 	ATA_DNXFER_QUIET	= (1 << 31),
 };
 
+#define ATA_PORT_TYPE_NAME	"ata_port"
+
 extern atomic_t ata_print_id;
 extern int atapi_passthru16;
 extern int libata_fua;