Subject: Patch "genirq: Respect IRQCHIP_SKIP_SET_WAKE in irq_chip_set_wake_parent()" has been added to the 5.0-stable tree

From: <[email-masked]>
Date: Mon, 15 Apr 2019 14:14:53 +0200

This is a note to let you know that I've just added the patch titled

    genirq: Respect IRQCHIP_SKIP_SET_WAKE in irq_chip_set_wake_parent()

to the 5.0-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     genirq-respect-irqchip_skip_set_wake-in-irq_chip_set_wake_parent.patch
and it can be found in the queue-5.0 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <[email-masked]> know about it.

>From 325aa19598e410672175ed50982f902d4e3f31c5 Mon Sep 17 00:00:00 2001
From: Stephen Boyd <[email-masked]>
Date: Mon, 25 Mar 2019 11:10:26 -0700
Subject: genirq: Respect IRQCHIP_SKIP_SET_WAKE in irq_chip_set_wake_parent()

From: Stephen Boyd <[email-masked]>

commit 325aa19598e410672175ed50982f902d4e3f31c5 upstream.

If a child irqchip calls irq_chip_set_wake_parent() but its parent irqchip
has the IRQCHIP_SKIP_SET_WAKE flag set an error is returned.

This is inconsistent behaviour vs. set_irq_wake_real() which returns 0 when
the irqchip has the IRQCHIP_SKIP_SET_WAKE flag set. It doesn't attempt to
walk the chain of parents and set irq wake on any chips that don't have the
flag set either. If the intent is to call the .irq_set_wake() callback of
the parent irqchip, then we expect irqchip implementations to omit the
IRQCHIP_SKIP_SET_WAKE flag and implement an .irq_set_wake() function that
calls irq_chip_set_wake_parent().

The problem has been observed on a Qualcomm sdm845 device where set wake
fails on any GPIO interrupts after applying work in progress wakeup irq
patches to the GPIO driver. The chain of chips looks like this:

     QCOM GPIO -> QCOM PDC (SKIP) -> ARM GIC (SKIP)

The GPIO controllers parent is the QCOM PDC irqchip which in turn has ARM
GIC as parent.  The QCOM PDC irqchip has the IRQCHIP_SKIP_SET_WAKE flag
set, and so does the grandparent ARM GIC.

The GPIO driver doesn't know if the parent needs to set wake or not, so it
unconditionally calls irq_chip_set_wake_parent() causing this function to
return a failure because the parent irqchip (PDC) doesn't have the
.irq_set_wake() callback set. Returning 0 instead makes everything work and
irqs from the GPIO controller can be configured for wakeup.

Make it consistent by returning 0 (success) from irq_chip_set_wake_parent()
when a parent chip has IRQCHIP_SKIP_SET_WAKE set.

[ tglx: Massaged changelog ]

Fixes: 08b55e2a9208e ("genirq: Add irqchip_set_wake_parent")
Signed-off-by: Stephen Boyd <[email-masked]>
Signed-off-by: Thomas Gleixner <[email-masked]>
Acked-by: Marc Zyngier <[email-masked]>
Cc: [email-masked]
Cc: [email-masked]
Cc: Lina Iyer <[email-masked]>
Cc: [email-masked]
Link: https://lkml.kernel.org/r/[email-masked]
Signed-off-by: Greg Kroah-Hartman <[email-masked]>

---
 kernel/irq/chip.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -1384,6 +1384,10 @@ int irq_chip_set_vcpu_affinity_parent(st
 int irq_chip_set_wake_parent(struct irq_data *data, unsigned int on)
 {
 	data = data->parent_data;
+
+	if (data->chip->flags & IRQCHIP_SKIP_SET_WAKE)
+		return 0;
+
 	if (data->chip->irq_set_wake)
 		return data->chip->irq_set_wake(data, on);

Patches currently in stable-queue which might be from [email-masked] are

queue-5.0/genirq-respect-irqchip_skip_set_wake-in-irq_chip_set_wake_parent.patch

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