netdev - [PATCH RFC net-next 2/3] net: phylink: add functions to block/unblock rx clock stop

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Message-Id: <E1tpPtu-005Soa-Ac@rmk-PC.armlinux.org.uk>
Date: Tue, 04 Mar 2025 10:53:26 +0000
From: "Russell King (Oracle)" <rmk+kernel@...linux.org.uk>
To: Jon Hunter <jonathanh@...dia.com>,
	 Thierry Reding <treding@...dia.com>,
	 "Lad,
	 Prabhakar" <prabhakar.csengg@...il.com>
Cc: Alexandre Torgue <alexandre.torgue@...s.st.com>,
	Andrew Lunn <andrew@...n.ch>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Heiner Kallweit <hkallweit1@...il.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 RFC net-next 2/3] net: phylink: add functions to block/unblock
 rx clock stop

Some MACs require the PHY receive clock to be running to complete setup
actions. This may fail if the PHY has negotiated EEE, the MAC supports
receive clock stop, and the link has entered LPI state. Provide a pair
of APIs that MAC drivers can use to temporarily block the PHY disabling
the receive clock.

Signed-off-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>
---
 drivers/net/phy/phylink.c | 62 +++++++++++++++++++++++++++++++--------
 include/linux/phylink.h   |  3 ++
 2 files changed, 53 insertions(+), 12 deletions(-)

diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index 0aae0bb2a254..9a62808cf935 100644
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -88,6 +88,7 @@ struct phylink {
 	bool mac_enable_tx_lpi;
 	bool mac_tx_clk_stop;
 	u32 mac_tx_lpi_timer;
+	u8 mac_rx_clk_stop_blocked;
 
 	struct sfp_bus *sfp_bus;
 	bool sfp_may_have_phy;
@@ -2592,6 +2593,55 @@ void phylink_stop(struct phylink *pl)
 }
 EXPORT_SYMBOL_GPL(phylink_stop);
 
+
+void phylink_rx_clk_stop_block(struct phylink *pl)
+{
+	ASSERT_RTNL();
+
+	if (pl->mac_rx_clk_stop_blocked == U8_MAX) {
+		phylink_warn(pl, "%s called too many times - ignoring\n",
+			     __func__);
+		dump_stack();
+		return;
+	}
+
+	/* Disable PHY receive clock stop if this is the first time this
+	 * function has been called and clock-stop was previously enabled.
+	 */
+	if (pl->mac_rx_clk_stop_blocked++ == 0 &&
+	    pl->mac_supports_eee_ops && pl->phydev)
+	    pl->config->eee_rx_clk_stop_enable)
+		phy_eee_rx_clock_stop(pl->phydev, false);
+}
+
+/**
+ * phylink_rx_clk_stop_unblock() - unblock PHY ability to stop receive clock
+ * @pl: a pointer to a &struct phylink returned from phylink_create()
+ *
+ * All calls to phylink_rx_clk_stop_block() must be balanced with a
+ * corresponding call to phylink_rx_clk_stop_unblock() to restore the PHYs
+ * clock stop ability.
+ */
+void phylink_rx_clk_stop_unblock(struct phylink *pl)
+{
+	ASSERT_RTNL();
+
+	if (pl->mac_rx_clk_stop_blocked == 0) {
+		phylink_warn(pl, "%s called too many times - ignoring\n",
+			     __func__);
+		dump_stack();
+		return;
+	}
+
+	/* Re-enable PHY receive clock stop if the number of unblocks matches
+	 * the number of calls to the block function above.
+	 */
+	if (--pl->mac_rx_clk_stop_blocked == 0 &&
+	    pl->mac_supports_eee_ops && pl->phydev &&
+	    pl->config->eee_rx_clk_stop_enable)
+		phy_eee_rx_clock_stop(pl->phydev, true);
+}
+
 /**
  * phylink_suspend() - handle a network device suspend event
  * @pl: a pointer to a &struct phylink returned from phylink_create()
@@ -2649,18 +2699,6 @@ void phylink_resume(struct phylink *pl)
 
 	ASSERT_RTNL();
 
-	if (pl->mac_supports_eee_ops && pl->phydev) {
-		/* Explicitly configure whether the PHY is allowed to stop its
-		 * receive clock on resume to ensure that it is correctly
-		 * configured.
-		 */
-		ret = phy_eee_rx_clock_stop(pl->phydev,
-					    pl->config->eee_rx_clk_stop_enable);
-		if (ret == -EOPNOTSUPP)
-			phylink_warn(pl, "failed to set rx clock stop: %pe\n",
-				     ERR_PTR(ret));
-	}
-
 	if (test_bit(PHYLINK_DISABLE_MAC_WOL, &pl->phylink_disable_state)) {
 		/* Wake-on-Lan enabled, MAC handling */
 
diff --git a/include/linux/phylink.h b/include/linux/phylink.h
index 08df65f6867a..249c437d6b7b 100644
--- a/include/linux/phylink.h
+++ b/include/linux/phylink.h
@@ -698,6 +698,9 @@ int phylink_pcs_pre_init(struct phylink *pl, struct phylink_pcs *pcs);
 void phylink_start(struct phylink *);
 void phylink_stop(struct phylink *);
 
+void phylink_rx_clk_stop_block(struct phylink *);
+void phylink_rx_clk_stop_unblock(struct phylink *);
+
 void phylink_suspend(struct phylink *pl, bool mac_wol);
 void phylink_resume(struct phylink *pl);
 
-- 
2.30.2