[PATCH 4.14 43/92] stmmac: fix DMA channel hang in half-duplex mode

From: Greg Kroah-Hartman
Date: Fri Jul 20 2018 - 08:35:24 EST


4.14-stable review patch. If anyone has any objections, please let me know.

------------------

From: Bhadram Varka <vbhadram@xxxxxxxxxx>

[ Upstream commit b6cfffa7ad923c73f317ea50fd4ebcb3b4b6669c ]

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@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 10 ++++++++++
1 file changed, 10 insertions(+)

--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -914,6 +914,7 @@ static void stmmac_check_pcs_mode(struct
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];
@@ -955,6 +956,15 @@ static int stmmac_init_phy(struct net_de
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