[PATCH v1 net] stmmac: fix DMA channel hang in half-duplex mode

[PATCH v1 net] stmmac: fix DMA channel hang in half-duplex mode

[Bhadram Varka]

HW does not support Half-duplex mode in multi-queue
scenario. Fix it by not advertising the Half-Duplex
mode if multi-queue enabled.

Signed-off-by: Bhadram Varka <vbhadram@nvidia.com>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index e79b0d7..cba46b6 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -928,6 +928,7 @@ static void stmmac_check_pcs_mode(struct stmmac_priv *priv)
 static int stmmac_init_phy(struct net_device *dev)
 {
 	struct stmmac_priv *priv = netdev_priv(dev);
+	u32 tx_cnt = priv->plat->tx_queues_to_use;
 	struct phy_device *phydev;
 	char phy_id_fmt[MII_BUS_ID_SIZE + 3];
 	char bus_id[MII_BUS_ID_SIZE];
@@ -969,6 +970,15 @@ static int stmmac_init_phy(struct net_device *dev)
 					 SUPPORTED_1000baseT_Full);
 
 	/*
+	 * Half-duplex mode not supported with multiqueue
+	 * half-duplex can only works with single queue
+	 */
+	if (tx_cnt > 1)
+		phydev->supported &= ~(SUPPORTED_1000baseT_Half |
+				       SUPPORTED_100baseT_Half |
+				       SUPPORTED_10baseT_Half);
+
+	/*
 	 * Broken HW is sometimes missing the pull-up resistor on the
 	 * MDIO line, which results in reads to non-existent devices returning
 	 * 0 rather than 0xffff. Catch this here and treat 0 as a non-existent
-- 
2.7.4

Re: [PATCH v1 net] stmmac: fix DMA channel hang in half-duplex mode

[David Miller]

From: Bhadram Varka <vbhadram@nvidia.com>
Date: Sun, 17 Jun 2018 20:02:05 +0530

> HW does not support Half-duplex mode in multi-queue
> scenario. Fix it by not advertising the Half-Duplex
> mode if multi-queue enabled.
> 
> Signed-off-by: Bhadram Varka <vbhadram@nvidia.com>

Applied and queued up for -stable.