Subject: [PATCH 47/52] net: phy: avoid clearing PHY interrupts twice in irq handler

From: Heiner Kallweit <[email-masked]>
Date: Sun, 1 Mar 2020 21:36:09 +0100

[ Upstream commit 249bc9744e165abe74ae326f43e9d70bad54c3b7 ]

On all PHY drivers that implement did_interrupt() reading the interrupt
status bits clears them. This means we may loose an interrupt that
is triggered between calling did_interrupt() and phy_clear_interrupt().
As part of the fix make it a requirement that did_interrupt() clears
the interrupt.

The Fixes tag refers to the first commit where the patch applies
cleanly.

Fixes: 49644e68f472 ("net: phy: add callback for custom interrupt handler to struct phy_driver")
Reported-by: Michael Walle <[email-masked]>
Signed-off-by: Heiner Kallweit <[email-masked]>
Signed-off-by: David S. Miller <[email-masked]>
---
 drivers/net/phy/phy.c | 3 ++-
 include/linux/phy.h   | 1 +
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
index 105d389b58e7..ea890d802ffe 100644
--- a/drivers/net/phy/phy.c
+++ b/drivers/net/phy/phy.c
@@ -761,7 +761,8 @@ static irqreturn_t phy_interrupt(int irq, void *phy_dat)
 		phy_trigger_machine(phydev);
 	}
 
-	if (phy_clear_interrupt(phydev))
+	/* did_interrupt() may have cleared the interrupt already */
+	if (!phydev->drv->did_interrupt && phy_clear_interrupt(phydev))
 		goto phy_err;
 	return IRQ_HANDLED;
 
diff --git a/include/linux/phy.h b/include/linux/phy.h
index 3d5d53313e6c..bf87c59a98bb 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -524,6 +524,7 @@ struct phy_driver {
 	/*
 	 * Checks if the PHY generated an interrupt.
 	 * For multi-PHY devices with shared PHY interrupt pin
+	 * Set interrupt bits have to be cleared.
 	 */
 	int (*did_interrupt)(struct phy_device *phydev);
 
-- 
2.20.1