linux-kernel - [PATCH stable 5.4 1/2] Revert "net: bcmgenet: use RGMII loopback for MAC reset"

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Message-Id: <20240516211153.140679-2-opendmb@gmail.com>
Date: Thu, 16 May 2024 14:11:52 -0700
From: Doug Berger <opendmb@...il.com>
To: stable@...r.kernel.org
Cc: Doug Berger <opendmb@...il.com>,
	Florian Fainelli <f.fainelli@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	bcm-kernel-feedback-list@...adcom.com,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH stable 5.4 1/2] Revert "net: bcmgenet: use RGMII loopback for MAC reset"

[ Upstream commit 612eb1c3b9e504de24136c947ed7c07bc342f3aa ]

This reverts commit 3a55402c93877d291b0a612d25edb03d1b4b93ac.

This is not a good solution when connecting to an external switch
that may not support the isolation of the TXC signal resulting in
output driver contention on the pin.

A different solution is necessary.

Signed-off-by: Doug Berger <opendmb@...il.com>
Acked-by: Florian Fainelli <f.fainelli@...il.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
[Adjusted to accommodate lack of commit 4f8d81b77e66]
Signed-off-by: Doug Berger <opendmb@...il.com>
---
 .../net/ethernet/broadcom/genet/bcmgenet.c    |  2 ++
 drivers/net/ethernet/broadcom/genet/bcmmii.c  | 33 -------------------
 2 files changed, 2 insertions(+), 33 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/genet/bcmgenet.c b/drivers/net/ethernet/broadcom/genet/bcmgenet.c
index 380bf7a328ba..2afd056056fb 100644
--- a/drivers/net/ethernet/broadcom/genet/bcmgenet.c
+++ b/drivers/net/ethernet/broadcom/genet/bcmgenet.c
@@ -2015,6 +2015,8 @@ static void reset_umac(struct bcmgenet_priv *priv)
 
 	/* issue soft reset with (rg)mii loopback to ensure a stable rxclk */
 	bcmgenet_umac_writel(priv, CMD_SW_RESET | CMD_LCL_LOOP_EN, UMAC_CMD);
+	udelay(2);
+	bcmgenet_umac_writel(priv, 0, UMAC_CMD);
 }
 
 static void bcmgenet_intr_disable(struct bcmgenet_priv *priv)
diff --git a/drivers/net/ethernet/broadcom/genet/bcmmii.c b/drivers/net/ethernet/broadcom/genet/bcmmii.c
index 026f00ccaa0c..213434aaf07f 100644
--- a/drivers/net/ethernet/broadcom/genet/bcmmii.c
+++ b/drivers/net/ethernet/broadcom/genet/bcmmii.c
@@ -187,38 +187,8 @@ int bcmgenet_mii_config(struct net_device *dev, bool init)
 	const char *phy_name = NULL;
 	u32 id_mode_dis = 0;
 	u32 port_ctrl;
-	int bmcr = -1;
-	int ret;
 	u32 reg;
 
-	/* MAC clocking workaround during reset of umac state machines */
-	reg = bcmgenet_umac_readl(priv, UMAC_CMD);
-	if (reg & CMD_SW_RESET) {
-		/* An MII PHY must be isolated to prevent TXC contention */
-		if (priv->phy_interface == PHY_INTERFACE_MODE_MII) {
-			ret = phy_read(phydev, MII_BMCR);
-			if (ret >= 0) {
-				bmcr = ret;
-				ret = phy_write(phydev, MII_BMCR,
-						bmcr | BMCR_ISOLATE);
-			}
-			if (ret) {
-				netdev_err(dev, "failed to isolate PHY\n");
-				return ret;
-			}
-		}
-		/* Switch MAC clocking to RGMII generated clock */
-		bcmgenet_sys_writel(priv, PORT_MODE_EXT_GPHY, SYS_PORT_CTRL);
-		/* Ensure 5 clks with Rx disabled
-		 * followed by 5 clks with Reset asserted
-		 */
-		udelay(4);
-		reg &= ~(CMD_SW_RESET | CMD_LCL_LOOP_EN);
-		bcmgenet_umac_writel(priv, reg, UMAC_CMD);
-		/* Ensure 5 more clocks before Rx is enabled */
-		udelay(2);
-	}
-
 	priv->ext_phy = !priv->internal_phy &&
 			(priv->phy_interface != PHY_INTERFACE_MODE_MOCA);
 
@@ -250,9 +220,6 @@ int bcmgenet_mii_config(struct net_device *dev, bool init)
 		phy_set_max_speed(phydev, SPEED_100);
 		bcmgenet_sys_writel(priv,
 				    PORT_MODE_EXT_EPHY, SYS_PORT_CTRL);
-		/* Restore the MII PHY after isolation */
-		if (bmcr >= 0)
-			phy_write(phydev, MII_BMCR, bmcr);
 		break;
 
 	case PHY_INTERFACE_MODE_REVMII:
-- 
2.34.1