From: Himanshu Madhani <himanshu.madhani@cavium.com>
Date: Sun, 3 Jun 2018 22:09:53 -0700
Subject: [PATCH] scsi: qla2xxx: Fix setting lower transfer speed if GPSC fails
Git-commit: 413c2f33489b134e3cc65d9c3ff7861e8fdfe899
References: bsc#1086327,FATE#324903
Patch-Mainline: v4.18-rc1

This patch prevents driver from setting lower default speed of 1 GB/sec,
if the switch does not support Get Port Speed Capabilities (GPSC)
command. Setting this default speed results into much lower write
performance for large sequential WRITE.  This patch modifies driver to
check for gpsc_supported flags and prevents driver from issuing
MBC_SET_PORT_PARAM (001Ah) to set default speed of 1 GB/sec. If driver
does not send this mailbox command, firmware assumes maximum supported
link speed and will operate at the max speed.

Cc: stable@vger.kernel.org
Signed-off-by: Himanshu Madhani <himanshu.madhani@cavium.com>
Reported-by: Eda Zhou <ezhou@redhat.com>
Reviewed-by: Ewan D. Milne <emilne@redhat.com>
Tested-by: Ewan D. Milne <emilne@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Hannes Reinecke <hare@suse.com>
---
 drivers/scsi/qla2xxx/qla_init.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/qla2xxx/qla_init.c b/drivers/scsi/qla2xxx/qla_init.c
index 8f55dd44adae..636960ad029a 100644
--- a/drivers/scsi/qla2xxx/qla_init.c
+++ b/drivers/scsi/qla2xxx/qla_init.c
@@ -5037,7 +5037,8 @@ qla2x00_iidma_fcport(scsi_qla_host_t *vha, fc_port_t *fcport)
 		return;
 
 	if (fcport->fp_speed == PORT_SPEED_UNKNOWN ||
-	    fcport->fp_speed > ha->link_data_rate)
+	    fcport->fp_speed > ha->link_data_rate ||
+	    !ha->flags.gpsc_supported)
 		return;
 
 	rval = qla2x00_set_idma_speed(vha, fcport->loop_id, fcport->fp_speed,
-- 
2.12.3