[PATCH 24/25] qla2xxx: Remove extra register read

Himanshu Madhani
2017-05-19T22:30:31Z

From: Quinn Tran <quinn.tran@cavium.com>

Register read is expensive in IO path, remove extra register
read in each interrupt processing to improve performance.

Signed-off-by: Quinn Tran <quinn.tran@cavium.com>
Signed-off-by: Himanshu Madhani <himanshu.madhani@cavium.com>
---
drivers/scsi/qla2xxx/qla_iocb.c | 4 +++-
drivers/scsi/qla2xxx/qla_target.c | 11 ++---------
2 files changed, 5 insertions(+), 10 deletions(-)

diff --git a/drivers/scsi/qla2xxx/qla_iocb.c b/drivers/scsi/qla2xxx/qla_iocb.c
index ea027f6a7fd4..8404f17f3c6c 100644
--- a/drivers/scsi/qla2xxx/qla_iocb.c
+++ b/drivers/scsi/qla2xxx/qla_iocb.c
@@ -464,7 +464,9 @@ qla2x00_start_iocbs(struct scsi_qla_host *vha, struct req_que *req)
req->ring_ptr++;

/* Set chip new ring index. */
- if (ha->mqenable || IS_QLA83XX(ha) || IS_QLA27XX(ha)) {
+ if (ha->mqenable || IS_QLA27XX(ha)) {
+ WRT_REG_DWORD(req->req_q_in, req->ring_index);
+ } else if (IS_QLA83XX(ha)) {
WRT_REG_DWORD(req->req_q_in, req->ring_index);
RD_REG_DWORD_RELAXED(&ha->iobase->isp24.hccr);
} else if (IS_QLAFX00(ha)) {
diff --git a/drivers/scsi/qla2xxx/qla_target.c b/drivers/scsi/qla2xxx/qla_target.c
index 95aad9c329d7..f42313e49443 100644
--- a/drivers/scsi/qla2xxx/qla_target.c
+++ b/drivers/scsi/qla2xxx/qla_target.c
@@ -2223,11 +2223,10 @@ static void qlt_unmap_sg(struct scsi_qla_host *vha, struct qla_tgt_cmd *cmd)
static int qlt_check_reserve_free_req(struct scsi_qla_host *vha,
uint32_t req_cnt)
{
- uint32_t cnt, cnt_in;
+ uint32_t cnt;

if (vha->req->cnt < (req_cnt + 2)) {
cnt = (uint16_t)RD_REG_DWORD(vha->req->req_q_out);
- cnt_in = (uint16_t)RD_REG_DWORD(vha->req->req_q_in);

if (vha->req->ring_index < cnt)
vha->req->cnt = cnt - vha->req->ring_index;
@@ -2235,14 +2234,8 @@ static int qlt_check_reserve_free_req(struct scsi_qla_host *vha,
vha->req->cnt = vha->req->length -
(vha->req->ring_index - cnt);

- if (unlikely(vha->req->cnt < (req_cnt + 2))) {
- ql_dbg(ql_dbg_io, vha, 0x305a,
- "qla_target(%d): There is no room in the request ring: vha->req->ring_index=%d, vha->req->cnt=%d, req_cnt=%d Req-out=%d Req-in=%d Req-Length=%d\n",
- vha->vp_idx, vha->req->ring_index,
- vha->req->cnt, req_cnt, cnt, cnt_in,
- vha->req->length);
+ if (unlikely(vha->req->cnt < (req_cnt + 2)))
return -EAGAIN;
- }
}

vha->req->cnt -= req_cnt;
--
2.12.0