netdev - [PATCH net-next 5/5] net: stmmac: block PHY RXC clock-stop

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Message-Id: <E1tvO6p-008Vjz-Qy@rmk-PC.armlinux.org.uk>
Date: Thu, 20 Mar 2025 22:11:27 +0000
From: "Russell King (Oracle)" <rmk+kernel@...linux.org.uk>
To: Andrew Lunn <andrew@...n.ch>,
	Heiner Kallweit <hkallweit1@...il.com>
Cc: Alexandre Torgue <alexandre.torgue@...s.st.com>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	linux-arm-kernel@...ts.infradead.org,
	linux-stm32@...md-mailman.stormreply.com,
	Maxime Coquelin <mcoquelin.stm32@...il.com>,
	netdev@...r.kernel.org,
	Paolo Abeni <pabeni@...hat.com>
Subject: [PATCH net-next 5/5] net: stmmac: block PHY RXC clock-stop

The DesignWare core requires the receive clock to be running during
certain operations. Ensure that we block PHY RXC clock-stop during
these operations.

This is a best-efforts change - not everywhere can be covered by this
because of net's core locking, which means we can't access the MDIO
bus to configure the PHY to disable RXC clock-stop in certain areas.
These are marked with FIXME comments.

Signed-off-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>
---
 .../net/ethernet/stmicro/stmmac/stmmac_main.c | 27 +++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 860f800cd014..a4f2c98e851a 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -3484,9 +3484,18 @@ static int stmmac_hw_setup(struct net_device *dev, bool ptp_register)
 	if (priv->hw->phylink_pcs)
 		phylink_pcs_pre_init(priv->phylink, priv->hw->phylink_pcs);
 
+	/* Note that clk_rx_i must be running for reset to complete. This
+	 * clock may also be required when setting the MAC address.
+	 *
+	 * Block the receive clock stop for LPI mode at the PHY in case
+	 * the link is established with EEE mode active.
+	 */
+	phylink_rx_clk_stop_block(priv->phylink);
+
 	/* DMA initialization and SW reset */
 	ret = stmmac_init_dma_engine(priv);
 	if (ret < 0) {
+		phylink_rx_clk_stop_unblock(priv->phylink);
 		netdev_err(priv->dev, "%s: DMA engine initialization failed\n",
 			   __func__);
 		return ret;
@@ -3494,6 +3503,7 @@ static int stmmac_hw_setup(struct net_device *dev, bool ptp_register)
 
 	/* Copy the MAC addr into the HW  */
 	stmmac_set_umac_addr(priv, priv->hw, dev->dev_addr, 0);
+	phylink_rx_clk_stop_unblock(priv->phylink);
 
 	/* PS and related bits will be programmed according to the speed */
 	if (priv->hw->pcs) {
@@ -3604,7 +3614,9 @@ static int stmmac_hw_setup(struct net_device *dev, bool ptp_register)
 	/* Start the ball rolling... */
 	stmmac_start_all_dma(priv);
 
+	phylink_rx_clk_stop_block(priv->phylink);
 	stmmac_set_hw_vlan_mode(priv, priv->hw);
+	phylink_rx_clk_stop_unblock(priv->phylink);
 
 	return 0;
 }
@@ -5888,6 +5900,9 @@ static void stmmac_tx_timeout(struct net_device *dev, unsigned int txqueue)
  *  whenever multicast addresses must be enabled/disabled.
  *  Return value:
  *  void.
+ *
+ *  FIXME: This may need RXC to be running, but it may be called with BH
+ *  disabled, which means we can't call phylink_rx_clk_stop*().
  */
 static void stmmac_set_rx_mode(struct net_device *dev)
 {
@@ -6020,7 +6035,9 @@ static int stmmac_set_features(struct net_device *netdev,
 	else
 		priv->hw->hw_vlan_en = false;
 
+	phylink_rx_clk_stop_block(priv->phylink);
 	stmmac_set_hw_vlan_mode(priv, priv->hw);
+	phylink_rx_clk_stop_unblock(priv->phylink);
 
 	return 0;
 }
@@ -6304,7 +6321,9 @@ static int stmmac_set_mac_address(struct net_device *ndev, void *addr)
 	if (ret)
 		goto set_mac_error;
 
+	phylink_rx_clk_stop_block(priv->phylink);
 	stmmac_set_umac_addr(priv, priv->hw, ndev->dev_addr, 0);
+	phylink_rx_clk_stop_unblock(priv->phylink);
 
 set_mac_error:
 	pm_runtime_put(priv->device);
@@ -6660,6 +6679,9 @@ static int stmmac_vlan_update(struct stmmac_priv *priv, bool is_double)
 	return stmmac_update_vlan_hash(priv, priv->hw, hash, pmatch, is_double);
 }
 
+/* FIXME: This may need RXC to be running, but it may be called with BH
+ * disabled, which means we can't call phylink_rx_clk_stop*().
+ */
 static int stmmac_vlan_rx_add_vid(struct net_device *ndev, __be16 proto, u16 vid)
 {
 	struct stmmac_priv *priv = netdev_priv(ndev);
@@ -6691,6 +6713,9 @@ static int stmmac_vlan_rx_add_vid(struct net_device *ndev, __be16 proto, u16 vid
 	return ret;
 }
 
+/* FIXME: This may need RXC to be running, but it may be called with BH
+ * disabled, which means we can't call phylink_rx_clk_stop*().
+ */
 static int stmmac_vlan_rx_kill_vid(struct net_device *ndev, __be16 proto, u16 vid)
 {
 	struct stmmac_priv *priv = netdev_priv(ndev);
@@ -7951,9 +7976,11 @@ int stmmac_resume(struct device *dev)
 
 	stmmac_hw_setup(ndev, false);
 	stmmac_init_coalesce(priv);
+	phylink_rx_clk_stop_block(priv->phylink);
 	stmmac_set_rx_mode(ndev);
 
 	stmmac_restore_hw_vlan_rx_fltr(priv, ndev, priv->hw);
+	phylink_rx_clk_stop_unblock(priv->phylink);
 
 	stmmac_enable_all_queues(priv);
 	stmmac_enable_all_dma_irq(priv);
-- 
2.30.2