Subject: [PATCH 16/31] net: stmmac: xgmac: fix incorrect XGMAC_VLAN_TAG register writting

From: Ong Boon Leong <[email-masked]>
Date: Fri, 7 Feb 2020 15:33:40 +0800

[ 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 <[email-masked]>
Signed-off-by: David S. Miller <[email-masked]>
---
 drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c
index 082f5ee9e525..9fb85faa8ed2 100644
--- 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(struct mac_device_info *hw, u32 hash,
 
 		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(struct mac_device_info *hw, u32 hash,
 
 		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;
-- 
2.21.1