Subject: [PATCH 15/31] net: stmmac: fix incorrect GMAC_VLAN_TAG register writting in GMAC4+

From: "Tan, Tee Min" <[email-masked]>
Date: Fri, 7 Feb 2020 15:33:20 +0800

[ Upstream commit 9eeeb3c9de4e3aeaa2bec097162f09305dd9f4c3 ]

It should always do a read of current value of GMAC_VLAN_TAG instead of
directly overwriting the register value.

Fixes: c1be0022df0d ("net: stmmac: Add VLAN HASH filtering support in GMAC4+")
Signed-off-by: Tan, Tee Min <[email-masked]>
Signed-off-by: Ong Boon Leong <[email-masked]>
Signed-off-by: David S. Miller <[email-masked]>
---
 drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c b/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c
index 40ca00e596dd..6e3d0ab0ecd6 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c
@@ -736,11 +736,14 @@ static void dwmac4_update_vlan_hash(struct mac_device_info *hw, u32 hash,
 				    __le16 perfect_match, bool is_double)
 {
 	void __iomem *ioaddr = hw->pcsr;
+	u32 value;
 
 	writel(hash, ioaddr + GMAC_VLAN_HASH_TABLE);
 
+	value = readl(ioaddr + GMAC_VLAN_TAG);
+
 	if (hash) {
-		u32 value = GMAC_VLAN_VTHM | GMAC_VLAN_ETV;
+		value |= GMAC_VLAN_VTHM | GMAC_VLAN_ETV;
 		if (is_double) {
 			value |= GMAC_VLAN_EDVLP;
 			value |= GMAC_VLAN_ESVL;
@@ -759,8 +762,6 @@ static void dwmac4_update_vlan_hash(struct mac_device_info *hw, u32 hash,
 
 		writel(value | perfect_match, ioaddr + GMAC_VLAN_TAG);
 	} else {
-		u32 value = readl(ioaddr + GMAC_VLAN_TAG);
-
 		value &= ~(GMAC_VLAN_VTHM | GMAC_VLAN_ETV);
 		value &= ~(GMAC_VLAN_EDVLP | GMAC_VLAN_ESVL);
 		value &= ~GMAC_VLAN_DOVLTC;
-- 
2.21.1