[PATCH v2 net-next 08/14] net: enetc: remove invalid code from enetc4_pl_mac_link_up()

[wei.fang@oss.nxp.com]

From: Wei Fang <wei.fang@nxp.com>

When adding phylink MAC operations support to the NETC switch driver,
Russell King pointed out several pieces of invalid logic in the
.mac_link_up() implementation (see [1] and [2]):

1) Half-duplex backpressure is not supported by the kernel, Ethernet
   relies on packet dropping for congestion management.

2) phylink_autoneg_inband() is unnecessary, as RGMII in-band status is
   not supported.

3) TX and RX pause are disabled in half-duplex mode, so there is no
   need to override them in .mac_link_up().

The same invalid logic is also present in enetc4_pl_mac_link_up(), so
remove the invalid code from it.

Link: https://lore.kernel.org/imx/acEIQqI-_oyCym8O@shell.armlinux.org.uk/ # 1
Link: https://lore.kernel.org/imx/acEFwqmAvWls_9Ef@shell.armlinux.org.uk/ # 2
Signed-off-by: Wei Fang <wei.fang@nxp.com>
---
 .../net/ethernet/freescale/enetc/enetc4_hw.h  |  1 -
 .../net/ethernet/freescale/enetc/enetc4_pf.c  | 35 +------------------
 2 files changed, 1 insertion(+), 35 deletions(-)

diff --git a/drivers/net/ethernet/freescale/enetc/enetc4_hw.h b/drivers/net/ethernet/freescale/enetc/enetc4_hw.h
index dea1fd0b8175..7a3ccc94b036 100644
--- a/drivers/net/ethernet/freescale/enetc/enetc4_hw.h
+++ b/drivers/net/ethernet/freescale/enetc/enetc4_hw.h
@@ -198,7 +198,6 @@
 #define  PM_CMD_CFG_CNT_FRM_EN		BIT(13)
 #define  PM_CMD_CFG_TXP			BIT(15)
 #define  PM_CMD_CFG_SEND_IDLE		BIT(16)
-#define  PM_CMD_CFG_HD_FCEN		BIT(18)
 #define  PM_CMD_CFG_SFD			BIT(21)
 #define  PM_CMD_CFG_TX_FLUSH		BIT(22)
 #define  PM_CMD_CFG_TX_LOWP_EN		BIT(23)
diff --git a/drivers/net/ethernet/freescale/enetc/enetc4_pf.c b/drivers/net/ethernet/freescale/enetc/enetc4_pf.c
index db7bad2c3cbd..a77ef62672c7 100644
--- a/drivers/net/ethernet/freescale/enetc/enetc4_pf.c
+++ b/drivers/net/ethernet/freescale/enetc/enetc4_pf.c
@@ -588,11 +588,6 @@ static void enetc4_mac_config(struct enetc_pf *pf, unsigned int mode,
 	case PHY_INTERFACE_MODE_RGMII_RXID:
 	case PHY_INTERFACE_MODE_RGMII_TXID:
 		val |= IFMODE_RGMII;
-		/* We need to enable auto-negotiation for the MAC
-		 * if its RGMII interface support In-Band status.
-		 */
-		if (phylink_autoneg_inband(mode))
-			val |= PM_IF_MODE_ENA;
 		break;
 	case PHY_INTERFACE_MODE_RMII:
 		val |= IFMODE_RMII;
@@ -690,22 +685,6 @@ static void enetc4_set_rmii_mac(struct enetc_pf *pf, int speed, int duplex)
 	enetc_port_mac_wr(si, ENETC4_PM_IF_MODE(0), val);
 }
 
-static void enetc4_set_hd_flow_control(struct enetc_pf *pf, bool enable)
-{
-	struct enetc_si *si = pf->si;
-	u32 old_val, val;
-
-	if (!pf->caps.half_duplex)
-		return;
-
-	old_val = enetc_port_mac_rd(si, ENETC4_PM_CMD_CFG(0));
-	val = u32_replace_bits(old_val, enable ? 1 : 0, PM_CMD_CFG_HD_FCEN);
-	if (val == old_val)
-		return;
-
-	enetc_port_mac_wr(si, ENETC4_PM_CMD_CFG(0), val);
-}
-
 static void enetc4_set_rx_pause(struct enetc_pf *pf, bool rx_pause)
 {
 	struct enetc_si *si = pf->si;
@@ -881,13 +860,11 @@ static void enetc4_pl_mac_link_up(struct phylink_config *config,
 	struct enetc_pf *pf = phylink_to_enetc_pf(config);
 	struct enetc_si *si = pf->si;
 	struct enetc_ndev_priv *priv;
-	bool hd_fc = false;
 
 	priv = netdev_priv(si->ndev);
 	enetc4_set_port_speed(priv, speed);
 
-	if (!phylink_autoneg_inband(mode) &&
-	    phy_interface_mode_is_rgmii(interface))
+	if (phy_interface_mode_is_rgmii(interface))
 		enetc4_set_rgmii_mac(pf, speed, duplex);
 
 	if (interface == PHY_INTERFACE_MODE_RMII)
@@ -899,18 +876,8 @@ static void enetc4_pl_mac_link_up(struct phylink_config *config,
 		 */
 		if (priv->active_offloads & ENETC_F_QBU)
 			tx_pause = false;
-	} else { /* DUPLEX_HALF */
-		if (tx_pause || rx_pause)
-			hd_fc = true;
-
-		/* As per 802.3 annex 31B, PAUSE frames are only supported
-		 * when the link is configured for full duplex operation.
-		 */
-		tx_pause = false;
-		rx_pause = false;
 	}
 
-	enetc4_set_hd_flow_control(pf, hd_fc);
 	enetc4_set_tx_pause(pf, priv->num_rx_rings, tx_pause);
 	enetc4_set_rx_pause(pf, rx_pause);
 	enetc4_mac_tx_enable(pf);
-- 
2.34.1