Re: [PATCH] genirq: Clarify that irq wake state is orthogonal to enable/disable

[Lina Iyer]

On Wed, Feb 05 2020 at 05:27 -0700, Thomas Gleixner wrote:
> Stephen Boyd <swboyd@xxxxxxxxxxxx> writes:
> > There's some confusion around if an irq that's disabled with
> > disable_irq() can still wake the system from sleep states such as
> > "suspend to RAM". Let's clarify this in the kernel documentation for
> > irq_set_irq_wake() so that it's clear that an irq can be disabled and
> > still wake the system if it has been marked for wakeup.
> >
> > Cc: Marc Zyngier <maz@xxxxxxxxxx>
> > Cc: Douglas Anderson <dianders@xxxxxxxxxxxx>
> > Cc: Lina Iyer <ilina@xxxxxxxxxxxxxx>
> > Cc: Maulik Shah <mkshah@xxxxxxxxxxxxxx>
> > Signed-off-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>
> > ---
> >  kernel/irq/manage.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
> > index 818b2802d3e7..fa8db98c8699 100644
> > --- a/kernel/irq/manage.c
> > +++ b/kernel/irq/manage.c
> > @@ -731,6 +731,11 @@ static int set_irq_wake_real(unsigned int irq, unsigned int on)
> >   *
> >   *	Wakeup mode lets this IRQ wake the system from sleep
> >   *	states like "suspend to RAM".
> > + *
> > + *	Note: irq enable/disable state is completely orthogonal
> > + *	to the enable/disable state of irq wake. An irq can be
> > + *	disabled with disable_irq() and still wake the system as
> > + *	long as the irq has wake enabled.
>
> It clearly should say that this is really depending on the hardware
> implementation of the particual interrupt chip whether disabled + wake
> mode is supported.
Could an irqchip flag be used to warn users that we may not wakeup from
suspend/resume if the interrupt if the hardware does not support wakeup
when disabled ?

--Lina