[PATCH 5.5 331/367] net: stmmac: xgmac: fix incorrect XGMAC_VLAN_TAG register writting

Greg Kroah-Hartman
2020-02-10T12:54:28Z

From: Ong Boon Leong <boon.leong.ong@intel.com>

[ Upstream commit 907a076881f171254219faad05f46ac5baabedfb ]

We should always do a read of current value of XGMAC_VLAN_TAG instead of
directly overwriting the register value.

Fixes: 3cd1cfcba26e2 ("net: stmmac: Implement VLAN Hash Filtering in XGMAC")
Signed-off-by: Ong Boon Leong <boon.leong.ong@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

--- a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c
@@ -569,7 +569,9 @@ static void dwxgmac2_update_vlan_hash(st

writel(value, ioaddr + XGMAC_PACKET_FILTER);

- value = XGMAC_VLAN_VTHM | XGMAC_VLAN_ETV;
+ value = readl(ioaddr + XGMAC_VLAN_TAG);
+
+ value |= XGMAC_VLAN_VTHM | XGMAC_VLAN_ETV;
if (is_double) {
value |= XGMAC_VLAN_EDVLP;
value |= XGMAC_VLAN_ESVL;
@@ -584,7 +586,9 @@ static void dwxgmac2_update_vlan_hash(st

writel(value, ioaddr + XGMAC_PACKET_FILTER);

- value = XGMAC_VLAN_ETV;
+ value = readl(ioaddr + XGMAC_VLAN_TAG);
+
+ value |= XGMAC_VLAN_ETV;
if (is_double) {
value |= XGMAC_VLAN_EDVLP;
value |= XGMAC_VLAN_ESVL;