[dpdk-dev] [PATCH] net/bnxt: fix memory barriers

[Gavin Hu]

As there is an inclusive rte_io_wmb within the following rte_write32()
API who rings the doorbell, this makes the above rte_wmb unecessary and
remove it.

The doorbell ringing operation requires a rte_io_wmb immediately to make
it complete and visible to the device.

To read the doorbell response, which is held in the host CIO memory,
rte_cio_rmb is sufficient.

Fixes: 804e746c7b73 ("net/bnxt: add hardware resource manager init code")
Fixes: ca241d9a0952 ("net/bnxt: use I/O device memory read/write API")
Cc: stable at dpdk.org

Signed-off-by: Gavin Hu <gavin.hu at arm.com>
Reviewed-by: Steve Capper <steve.capper at arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang at arm.com>
Reviewed-by: Phil Yang <phil.yang at arm.com>
---
 drivers/net/bnxt/bnxt_hwrm.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/net/bnxt/bnxt_hwrm.c b/drivers/net/bnxt/bnxt_hwrm.c
index 9883fb5..ee07db9 100644
--- a/drivers/net/bnxt/bnxt_hwrm.c
+++ b/drivers/net/bnxt/bnxt_hwrm.c
@@ -115,9 +115,6 @@ static int bnxt_hwrm_send_message(struct bnxt *bp, void *msg,
 		data = (uint32_t *)&short_input;
 		msg_len = sizeof(short_input);
 
-		/* Sync memory write before updating doorbell */
-		rte_wmb();
-
 		max_req_len = BNXT_HWRM_SHORT_REQ_LEN;
 	}
 
@@ -137,11 +134,12 @@ static int bnxt_hwrm_send_message(struct bnxt *bp, void *msg,
 	/* Ring channel doorbell */
 	bar = (uint8_t *)bp->bar0 + mb_trigger_offset;
 	rte_write32(1, bar);
+	rte_io_wmb();
 
 	/* Poll for the valid bit */
 	for (i = 0; i < HWRM_CMD_TIMEOUT; i++) {
 		/* Sanity check on the resp->resp_len */
-		rte_rmb();
+		rte_cio_rmb();
 		if (resp->resp_len && resp->resp_len <= bp->max_resp_len) {
 			/* Last byte of resp contains the valid key */
 			valid = (uint8_t *)resp + resp->resp_len - 1;
-- 
2.7.4