linux-kernel - [PATCH stable 5.4 2/2] net: bcmgenet: keep MAC in reset until PHY is up

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Message-Id: <20240516211153.140679-3-opendmb@gmail.com>
Date: Thu, 16 May 2024 14:11:53 -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 2/2] net: bcmgenet: keep MAC in reset until PHY is up

[ Upstream commit 88f6c8bf1aaed5039923fb4c701cab4d42176275 ]

As noted in commit 28c2d1a7a0bf ("net: bcmgenet: enable loopback
during UniMAC sw_reset") the UniMAC must be clocked at least 5
cycles while the sw_reset is asserted to ensure a clean reset.

That commit enabled local loopback to provide an Rx clock from the
GENET sourced Tx clk. However, when connected in MII mode the Tx
clk is sourced by the PHY so if an EPHY is not supplying clocks
(e.g. when the link is down) the UniMAC does not receive the
necessary clocks.

This commit extends the sw_reset window until the PHY reports that
the link is up thereby ensuring that the clocks are being provided
to the MAC to produce a clean reset.

One consequence is that if the system attempts to enter a Wake on
LAN suspend state when the PHY link has not been active the MAC
may not have had a chance to initialize cleanly. In this case, we
remove the sw_reset and enable the WoL reception path as normal
with the hope that the PHY will provide the necessary clocks to
drive the WoL blocks if the link becomes active after the system
has entered suspend.

Fixes: 1c1008c793fa ("net: bcmgenet: add main driver file")
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>
---
 drivers/net/ethernet/broadcom/genet/bcmgenet.c     | 10 ++++------
 drivers/net/ethernet/broadcom/genet/bcmgenet_wol.c |  6 +++++-
 drivers/net/ethernet/broadcom/genet/bcmmii.c       |  6 ++++++
 3 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/genet/bcmgenet.c b/drivers/net/ethernet/broadcom/genet/bcmgenet.c
index 2afd056056fb..bf52bd643846 100644
--- a/drivers/net/ethernet/broadcom/genet/bcmgenet.c
+++ b/drivers/net/ethernet/broadcom/genet/bcmgenet.c
@@ -1991,6 +1991,8 @@ static void umac_enable_set(struct bcmgenet_priv *priv, u32 mask, bool enable)
 	u32 reg;
 
 	reg = bcmgenet_umac_readl(priv, UMAC_CMD);
+	if (reg & CMD_SW_RESET)
+		return;
 	if (enable)
 		reg |= mask;
 	else
@@ -2010,13 +2012,9 @@ static void reset_umac(struct bcmgenet_priv *priv)
 	bcmgenet_rbuf_ctrl_set(priv, 0);
 	udelay(10);
 
-	/* disable MAC while updating its registers */
-	bcmgenet_umac_writel(priv, 0, UMAC_CMD);
-
-	/* 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);
+	/* issue soft reset and disable MAC while updating its registers */
+	bcmgenet_umac_writel(priv, CMD_SW_RESET, 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/bcmgenet_wol.c b/drivers/net/ethernet/broadcom/genet/bcmgenet_wol.c
index a2da09da4907..8ebca6bf300e 100644
--- a/drivers/net/ethernet/broadcom/genet/bcmgenet_wol.c
+++ b/drivers/net/ethernet/broadcom/genet/bcmgenet_wol.c
@@ -132,8 +132,12 @@ int bcmgenet_wol_power_down_cfg(struct bcmgenet_priv *priv,
 		return -EINVAL;
 	}
 
-	/* disable RX */
+	/* Can't suspend with WoL if MAC is still in reset */
 	reg = bcmgenet_umac_readl(priv, UMAC_CMD);
+	if (reg & CMD_SW_RESET)
+		reg &= ~CMD_SW_RESET;
+
+	/* disable RX */
 	reg &= ~CMD_RX_EN;
 	bcmgenet_umac_writel(priv, reg, UMAC_CMD);
 	mdelay(10);
diff --git a/drivers/net/ethernet/broadcom/genet/bcmmii.c b/drivers/net/ethernet/broadcom/genet/bcmmii.c
index 213434aaf07f..56fad34461f7 100644
--- a/drivers/net/ethernet/broadcom/genet/bcmmii.c
+++ b/drivers/net/ethernet/broadcom/genet/bcmmii.c
@@ -96,6 +96,12 @@ void bcmgenet_mii_setup(struct net_device *dev)
 			       CMD_HD_EN |
 			       CMD_RX_PAUSE_IGNORE | CMD_TX_PAUSE_IGNORE);
 		reg |= cmd_bits;
+		if (reg & CMD_SW_RESET) {
+			reg &= ~CMD_SW_RESET;
+			bcmgenet_umac_writel(priv, reg, UMAC_CMD);
+			udelay(2);
+			reg |= CMD_TX_EN | CMD_RX_EN;
+		}
 		bcmgenet_umac_writel(priv, reg, UMAC_CMD);
 
 		priv->eee.eee_active = phy_init_eee(phydev, 0) >= 0;
-- 
2.34.1