[v2] genirq: Respect IRQCHIP_SKIP_SET_WAKE in irq_chip_set_wake_parent()
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Message ID 20190325181026.247796-1-swboyd@chromium.org
State New
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  • [v2] genirq: Respect IRQCHIP_SKIP_SET_WAKE in irq_chip_set_wake_parent()
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Commit Message

Stephen Boyd March 25, 2019, 6:10 p.m. UTC
This function returns an error if a child irqchip calls
irq_chip_set_wake_parent() but its parent irqchip has the
IRQCHIP_SKIP_SET_WAKE flag set. Let's return 0 for success here instead
because there isn't anything to do.

This keeps the behavior consistent with how set_irq_wake_real() is
implemented. That function 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().

This fixes a problem on my Qualcomm sdm845 device where I can't set wake
on any GPIO interrupts after I apply work in progress wakeup irq patches
to the GPIO driver. The chain of chips looks like this:

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

The GPIO controller is a child of the QCOM PDC irqchip which is a child
of the ARM GIC irqchip. 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.

Cc: Lina Iyer <ilina@codeaurora.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
---

Changes from v1:
 - Rewrote commit text
 - Changed to only look at parent flags instead of walking parent chain

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

Comments

Marc Zyngier March 26, 2019, 11:11 a.m. UTC | #1
Hi Stephen,

On 25/03/2019 18:10, Stephen Boyd wrote:
> This function returns an error if a child irqchip calls
> irq_chip_set_wake_parent() but its parent irqchip has the
> IRQCHIP_SKIP_SET_WAKE flag set. Let's return 0 for success here instead
> because there isn't anything to do.
> 
> This keeps the behavior consistent with how set_irq_wake_real() is
> implemented. That function 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().
> 
> This fixes a problem on my Qualcomm sdm845 device where I can't set wake
> on any GPIO interrupts after I apply work in progress wakeup irq patches
> to the GPIO driver. The chain of chips looks like this:
> 
>  ARM GIC (skip) -> QCOM PDC (skip) -> QCOM GPIO

nit: the parenting chain is actually built the other way around (we
don't express the 'child' relationship). This doesn't change anything to
the patch, but would make the reasoning a but easier to understand.

> 
> The GPIO controller is a child of the QCOM PDC irqchip which is a child
> of the ARM GIC irqchip. 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.
> 
> Cc: Lina Iyer <ilina@codeaurora.org>
> Cc: Marc Zyngier <marc.zyngier@arm.com>
> Signed-off-by: Stephen Boyd <swboyd@chromium.org>

Fixes: 08b55e2a9208e ("genirq: Add irqchip_set_wake_parent")
Acked-by: Marc Zyngier <marc.zyngier@arm.com>

Thanks,

	M.
Stephen Boyd March 26, 2019, 4:58 p.m. UTC | #2
Quoting Marc Zyngier (2019-03-26 04:11:56)
> Hi Stephen,
> 
> On 25/03/2019 18:10, Stephen Boyd wrote:
> > This function returns an error if a child irqchip calls
> > irq_chip_set_wake_parent() but its parent irqchip has the
> > IRQCHIP_SKIP_SET_WAKE flag set. Let's return 0 for success here instead
> > because there isn't anything to do.
> > 
> > This keeps the behavior consistent with how set_irq_wake_real() is
> > implemented. That function 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().
> > 
> > This fixes a problem on my Qualcomm sdm845 device where I can't set wake
> > on any GPIO interrupts after I apply work in progress wakeup irq patches
> > to the GPIO driver. The chain of chips looks like this:
> > 
> >  ARM GIC (skip) -> QCOM PDC (skip) -> QCOM GPIO
> 
> nit: the parenting chain is actually built the other way around (we
> don't express the 'child' relationship). This doesn't change anything to
> the patch, but would make the reasoning a but easier to understand.

I take it you want the sentence below to say 'parent' instead of 'child'
then?

> 
> > 
> > The GPIO controller is a child of the QCOM PDC irqchip which is a child
> > of the ARM GIC irqchip. 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.
> > 
> > Cc: Lina Iyer <ilina@codeaurora.org>
> > Cc: Marc Zyngier <marc.zyngier@arm.com>
> > Signed-off-by: Stephen Boyd <swboyd@chromium.org>
> 
> Fixes: 08b55e2a9208e ("genirq: Add irqchip_set_wake_parent")
> Acked-by: Marc Zyngier <marc.zyngier@arm.com>
> 

I'm happy to resend with the commit text clarified more and the above
tags added.

Patch
diff mbox series

diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index 3faef4a77f71..51128bea3846 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -1449,6 +1449,10 @@  int irq_chip_set_vcpu_affinity_parent(struct irq_data *data, void *vcpu_info)
 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);