From 240ebf303276af0676b2d46ce232292d269d19a9 Mon Sep 17 00:00:00 2001
From: Alexander Sverdlin <alexander.sverdlin@nokia.com>
Date: Fri, 29 May 2020 14:17:10 +0200
Subject: [PATCH 8/9] net: octeon: mgmt: Repair filling of RX ring
Git-commit: 0c34bb598c510e070160029f34efeeb217000f8d
Patch-mainline: v5.8-rc1
References: git-fixes

The removal of mips_swiotlb_ops exposed a problem in octeon_mgmt Ethernet
driver. mips_swiotlb_ops had an mb() after most of the operations and the
removal of the ops had broken the receive functionality of the driver.
My code inspection has shown no other places except
octeon_mgmt_rx_fill_ring() where an explicit barrier would be obviously
missing. The latter function however has to make sure that "ringing the
bell" doesn't happen before RX ring entry is really written.

The patch has been successfully tested on Octeon II.

Fixes: a999933db9ed ("MIPS: remove mips_swiotlb_ops")
Cc: stable@vger.kernel.org
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@nokia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Denis Kirjanov <denis.kirjanov@suse.com>
---
 drivers/net/ethernet/cavium/octeon/octeon_mgmt.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/ethernet/cavium/octeon/octeon_mgmt.c b/drivers/net/ethernet/cavium/octeon/octeon_mgmt.c
index cdd7e5da4a74..d375e438d805 100644
--- a/drivers/net/ethernet/cavium/octeon/octeon_mgmt.c
+++ b/drivers/net/ethernet/cavium/octeon/octeon_mgmt.c
@@ -235,6 +235,11 @@ static void octeon_mgmt_rx_fill_ring(struct net_device *netdev)
 
 		/* Put it in the ring.  */
 		p->rx_ring[p->rx_next_fill] = re.d64;
+		/* Make sure there is no reorder of filling the ring and ringing
+		 * the bell
+		 */
+		wmb();
+
 		dma_sync_single_for_device(p->dev, p->rx_ring_handle,
 					   ring_size_to_bytes(OCTEON_MGMT_RX_RING_SIZE),
 					   DMA_BIDIRECTIONAL);
-- 
2.16.4