From 4f060bf5900e8f17fb8cb8508dc08006b2a844b1 Mon Sep 17 00:00:00 2001
From: Phil Elwell <phil@raspberrypi.com>
Date: Tue, 15 Dec 2020 16:38:37 +0000
Subject: [PATCH] net: lan78xx: Ack pending PHY ints when resetting

lan78xx_link_reset explicitly clears the MAC's view of the PHY's IRQ
status. In doing so it potentially leaves the PHY with a pending
interrupt that will never be acknowledged, at which point no further
interrupts will be generated.

Avoid the problem by acknowledging any pending PHY interrupt after
clearing the MAC's status bit.

See: https://github.com/raspberrypi/linux/issues/2937

Signed-off-by: Phil Elwell <phil@raspberrypi.com>
---
 drivers/net/usb/lan78xx.c | 3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/net/usb/lan78xx.c
+++ b/drivers/net/usb/lan78xx.c
@@ -1181,6 +1181,9 @@ static int lan78xx_link_reset(struct lan
 	if (unlikely(ret < 0))
 		return -EIO;
 
+	/* Acknowledge any pending PHY interrupt, lest it be the last */
+	phy_read(phydev, LAN88XX_INT_STS);
+
 	mutex_lock(&phydev->lock);
 	phy_read_status(phydev);
 	link = phydev->link;
