From: Quinn Tran <quinn.tran@cavium.com>
Date: Thu, 28 Dec 2017 12:33:18 -0800
Subject: scsi: qla2xxx: Use shadow register for ISP27XX
Patch-mainline: v4.16-rc1
Git-commit: 1586e07a46b8e9fefdda22f763cfb1ba58f9c3cc
References: bsc#1077338

For ISP27XX, use shadow register to read FW provided REQQ's consumer
index. The shadow register is dma'ed by firmware.

Signed-off-by: Quinn Tran <quinn.tran@cavium.com>
Signed-off-by: Himanshu Madhani <himanshu.madhani@cavium.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Johannes Thumshirn <jthumshirn@suse.de>
---
 drivers/scsi/qla2xxx/qla_iocb.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/scsi/qla2xxx/qla_iocb.c
+++ b/drivers/scsi/qla2xxx/qla_iocb.c
@@ -2158,7 +2158,9 @@ __qla2x00_alloc_iocbs(struct qla_qpair *
 skip_cmd_array:
 	/* Check for room on request queue. */
 	if (req->cnt < req_cnt + 2) {
-		if (ha->mqenable || IS_QLA83XX(ha) || IS_QLA27XX(ha))
+		if (qpair->use_shadow_reg)
+			cnt = *req->out_ptr;
+		else if (ha->mqenable || IS_QLA83XX(ha) || IS_QLA27XX(ha))
 			cnt = RD_REG_DWORD(&reg->isp25mq.req_q_out);
 		else if (IS_P3P_TYPE(ha))
 			cnt = RD_REG_DWORD(&reg->isp82.req_q_out);