scsi: libsas: Try to retain programmed min linkrate for SATA min pathway unmatch fixing

Currently for fixing the linkrate matching during discovery such that the
linkrate of a SATA PHY does not exceed min pathway to initiator, we set the
SATA PHY programmed min linkrate to the same value as the programmed max
linkrate.

This is unnecessary, and we should be able to keep the same programmed min
linkrate if it is already lower than this new max programmed linkrate.

This patch makes that change.

In effect, this will not make much difference since we generally will
negotiate a linkrate at the programmed max linkrate, and the programmed min
linkrate will have no impact.
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/libsas/sas_expander.c

@@ -826,9 +826,14 @@ static struct domain_device *sas_ex_discover_end_dev(
 #ifdef CONFIG_SCSI_SAS_ATA
 	if ((phy->attached_tproto & SAS_PROTOCOL_STP) || phy->attached_sata_dev) {
 		if (child->linkrate > parent->min_linkrate) {
+			struct sas_phy *cphy = child->phy;
+			enum sas_linkrate min_prate = cphy->minimum_linkrate,
+				parent_min_lrate = parent->min_linkrate,
+				min_linkrate = (min_prate > parent_min_lrate) ?
+					       parent_min_lrate : 0;
 			struct sas_phy_linkrates rates = {
 				.maximum_linkrate = parent->min_linkrate,
-				.minimum_linkrate = parent->min_linkrate,
+				.minimum_linkrate = min_linkrate,
 			};
 			int ret;