FAILED: patch "[PATCH] net: dsa: mv88e6xxx: fix lockup on warm boot" failed to apply to 4.19-stable tree

The patch below does not apply to the 4.19-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 0395823b8d9a4d87bd1bf74359123461c2ae801b Mon Sep 17 00:00:00 2001
From: Russell King <[email protected]>
Date: Fri, 28 Feb 2020 19:39:41 +0000
Subject: [PATCH] net: dsa: mv88e6xxx: fix lockup on warm boot

If the switch is not hardware reset on a warm boot, interrupts can be left enabled, and possibly pending. This will cause us to enter an infinite loop trying to service an interrupt we are unable to handle, thereby preventing the kernel from booting.

Ensure that the global 2 interrupt sources are disabled before we claim the parent interrupt.

Observed on the ZII development revision B and C platforms with reworked serdes support, and using reboot -f to reboot the platform.

index 01503014b1ee..8fd483020c5b 100644
@@ -1099,6 +1099,13 @@ int mv88e6xxx_g2_irq_setup(struct mv88e6xxx_chip *chip)
 {
 	int err, irq, virq;
 
+	chip->g2_irq.masked = ~0;
+	mv88e6xxx_reg_lock(chip);
+	err = mv88e6xxx_g2_int_mask(chip, ~chip->g2_irq.masked);
+	mv88e6xxx_reg_unlock(chip);
+	if (err)
+		return err;
+
 	chip->g2_irq.domain = irq_domain_add_simple(
 		chip->dev->of_node, 16, 0, &mv88e6xxx_g2_irq_domain_ops, chip);
 	if (!chip->g2_irq.domain)

@@ -1108,7 +1115,6 @@ int mv88e6xxx_g2_irq_setup(struct mv88e6xxx_chip *chip)
 		irq_create_mapping(chip->g2_irq.domain, irq);
 
 	chip->g2_irq.chip = mv88e6xxx_g2_irq_chip;
-	chip->g2_irq.masked = ~0;
 
 	chip->device_irq = irq_find_mapping(chip->g1_irq.domain,
 					    MV88E6XXX_G1_STS_IRQ_DEVICE);