[PATCH v2 1/3] net: stmmac: xgmac: fix l4 filter port overwrite on register update

[muhammad . nazim . amirul . nazle . asmade]

From: Nazim Amirul <muhammad.nazim.amirul.nazle.asmade@xxxxxxxxxx>

The XGMAC_L4_ADDR register holds both source and destination port
match values. The current implementation overwrites the entire register
when configuring either port, so setting one silently erases the other.

Fix this by reading the register first, then masking and updating only
the relevant field before writing back.

Fixes: 425eabddaf0f ("net: stmmac: Implement L3/L4 Filters using TC Flower")
Signed-off-by: Rohan G Thomas <rohan.g.thomas@xxxxxxxxxx>
Signed-off-by: Nazim Amirul <muhammad.nazim.amirul.nazle.asmade@xxxxxxxxxx>
---
 .../ethernet/stmicro/stmmac/dwxgmac2_core.c   | 28 +++++++++++--------
 1 file changed, 16 insertions(+), 12 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c
index f02b434bbd50..52054f31376d 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c
@@ -1370,36 +1370,40 @@ static int dwxgmac2_config_l4_filter(struct mac_device_info *hw, u32 filter_no,
 		value &= ~XGMAC_L4PEN0;
 	}
 
-	value &= ~(XGMAC_L4SPM0 | XGMAC_L4SPIM0);
-	value &= ~(XGMAC_L4DPM0 | XGMAC_L4DPIM0);
 	if (sa) {
 		value |= XGMAC_L4SPM0;
 		if (inv)
 			value |= XGMAC_L4SPIM0;
+		else
+			value &= ~XGMAC_L4SPIM0;
 	} else {
 		value |= XGMAC_L4DPM0;
 		if (inv)
 			value |= XGMAC_L4DPIM0;
+		else
+			value &= ~XGMAC_L4DPIM0;
 	}
 
 	ret = dwxgmac2_filter_write(hw, filter_no, XGMAC_L3L4_CTRL, value);
 	if (ret)
 		return ret;
 
-	if (sa) {
-		value = FIELD_PREP(XGMAC_L4SP0, match);
+	ret = dwxgmac2_filter_read(hw, filter_no, XGMAC_L4_ADDR, &value);
+	if (ret)
+		return ret;
 
-		ret = dwxgmac2_filter_write(hw, filter_no, XGMAC_L4_ADDR, value);
-		if (ret)
-			return ret;
+	if (sa) {
+		value &= ~XGMAC_L4SP0;
+		value |= FIELD_PREP(XGMAC_L4SP0, match);
 	} else {
-		value = FIELD_PREP(XGMAC_L4DP0, match);
-
-		ret = dwxgmac2_filter_write(hw, filter_no, XGMAC_L4_ADDR, value);
-		if (ret)
-			return ret;
+		value &= ~XGMAC_L4DP0;
+		value |= FIELD_PREP(XGMAC_L4DP0, match);
 	}
 
+	ret = dwxgmac2_filter_write(hw, filter_no, XGMAC_L4_ADDR, value);
+	if (ret)
+		return ret;
+
 	if (!en)
 		return dwxgmac2_filter_write(hw, filter_no, XGMAC_L3L4_CTRL, 0);
 
-- 
2.43.7