linux-kernel - [PATCH RFC net-next v2 1/2] net: phy: allow a phy to opt-out of interrupt handling

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Message-Id: <20221228164008.1653348-2-michael@walle.cc>
Date:   Wed, 28 Dec 2022 17:40:07 +0100
From:   Michael Walle <michael@...le.cc>
To:     Xu Liang <lxu@...linear.com>, Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Russell King <linux@...linux.org.uk>,
        "David S . Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Michael Walle <michael@...le.cc>
Subject: [PATCH RFC net-next v2 1/2] net: phy: allow a phy to opt-out of interrupt handling

Until now, it is not possible for a PHY driver to disable interrupts
during runtime. If a driver offers the .config_intr() as well as the
.handle_interrupt() ops, it is eligible for interrupt handling.
Introduce a new flag for the dev_flags property of struct phy_device, which
can be set by PHY driver to skip interrupt setup and fall back to polling
mode.

At the moment, this is used for the MaxLinear PHY which has broken
interrupt handling and there is a need to disable interrupts in some
cases.

Signed-off-by: Michael Walle <michael@...le.cc>
---
 drivers/net/phy/phy_device.c | 7 +++++++
 include/linux/phy.h          | 2 ++
 2 files changed, 9 insertions(+)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 716870a4499c..e4562859ac00 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -1487,6 +1487,13 @@ int phy_attach_direct(struct net_device *dev, struct phy_device *phydev,
 
 	phydev->interrupts = PHY_INTERRUPT_DISABLED;
 
+	/* PHYs can request to use poll mode even though they have an
+	 * associated interrupt line. This could be the case if they
+	 * detect a broken interrupt handling.
+	 */
+	if (phydev->dev_flags & PHY_F_NO_IRQ)
+		phydev->irq = PHY_POLL;
+
 	/* Port is set to PORT_TP by default and the actual PHY driver will set
 	 * it to different value depending on the PHY configuration. If we have
 	 * the generic PHY driver we can't figure it out, thus set the old
diff --git a/include/linux/phy.h b/include/linux/phy.h
index 71eeb4e3b1fd..f1566c7e47a8 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -82,6 +82,8 @@ extern const int phy_10gbit_features_array[1];
 #define PHY_POLL_CABLE_TEST	0x00000004
 #define MDIO_DEVICE_IS_PHY	0x80000000
 
+#define PHY_F_NO_IRQ		0x80000000
+
 /**
  * enum phy_interface_t - Interface Mode definitions
  *
-- 
2.30.2