Subject: [PATCH AUTOSEL 4.19 043/158] net: stmmac: dwmac4: fix flow control issue

From: Sasha Levin <[email-masked]>
Date: Mon, 15 Jul 2019 10:16:14 -0400

From: Biao Huang <[email-masked]>

[ Upstream commit ee326fd01e79dfa42014d55931260b68b9fa3273 ]

Current dwmac4_flow_ctrl will not clear
GMAC_RX_FLOW_CTRL_RFE/GMAC_RX_FLOW_CTRL_RFE bits,
so MAC hw will keep flow control on although expecting
flow control off by ethtool. Add codes to fix it.

Fixes: 477286b53f55 ("stmmac: add GMAC4 core support")
Signed-off-by: Biao Huang <[email-masked]>
Signed-off-by: David S. Miller <[email-masked]>
Signed-off-by: Sasha Levin <[email-masked]>
---
 drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c b/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c
index a2f3db39221e..d0e6e1503581 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c
@@ -475,8 +475,9 @@ static void dwmac4_flow_ctrl(struct mac_device_info *hw, unsigned int duplex,
 	if (fc & FLOW_RX) {
 		pr_debug("\tReceive Flow-Control ON\n");
 		flow |= GMAC_RX_FLOW_CTRL_RFE;
-		writel(flow, ioaddr + GMAC_RX_FLOW_CTRL);
 	}
+	writel(flow, ioaddr + GMAC_RX_FLOW_CTRL);
+
 	if (fc & FLOW_TX) {
 		pr_debug("\tTransmit Flow-Control ON\n");
 
@@ -484,7 +485,7 @@ static void dwmac4_flow_ctrl(struct mac_device_info *hw, unsigned int duplex,
 			pr_debug("\tduplex mode: PAUSE %d\n", pause_time);
 
 		for (queue = 0; queue < tx_cnt; queue++) {
-			flow |= GMAC_TX_FLOW_CTRL_TFE;
+			flow = GMAC_TX_FLOW_CTRL_TFE;
 
 			if (duplex)
 				flow |=
@@ -492,6 +493,9 @@ static void dwmac4_flow_ctrl(struct mac_device_info *hw, unsigned int duplex,
 
 			writel(flow, ioaddr + GMAC_QX_TX_FLOW_CTRL(queue));
 		}
+	} else {
+		for (queue = 0; queue < tx_cnt; queue++)
+			writel(0, ioaddr + GMAC_QX_TX_FLOW_CTRL(queue));
 	}
 }
 
-- 
2.20.1