[PATCH] genirq: use irq_mask as fallback for irq_disable.

[PATCH] genirq: use irq_mask as fallback for irq_disable.

[Andreas Fenkart]

This is in line with irq_enable that uses the same fallback.
When masked, interrupts are still latched into the status register
so when unmasked there is an interrupt straight away.

Signed-off-by: Andreas Fenkart <andreas.fenkart@streamunlimited.com>
---
 kernel/irq/chip.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index cbd97ce..21f87b7 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -216,10 +216,11 @@ void irq_enable(struct irq_desc *desc)
 void irq_disable(struct irq_desc *desc)
 {
 	irq_state_set_disabled(desc);
-	if (desc->irq_data.chip->irq_disable) {
+	if (desc->irq_data.chip->irq_disable)
 		desc->irq_data.chip->irq_disable(&desc->irq_data);
-		irq_state_set_masked(desc);
-	}
+	else
+		desc->irq_data.chip->irq_mask(&desc->irq_data);
+	irq_state_set_masked(desc);
 }
 
 void irq_percpu_enable(struct irq_desc *desc, unsigned int cpu)
-- 
1.7.10.4

Re: [PATCH] genirq: use irq_mask as fallback for irq_disable.

[Andrew Morton]

On Fri, 19 Apr 2013 15:41:02 +0200 Andreas Fenkart <andreas.fenkart@streamunlimited.com> wrote:

> This is in line with irq_enable that uses the same fallback.
> When masked, interrupts are still latched into the status register
> so when unmasked there is an interrupt straight away.
> 
> ...
>
> --- a/kernel/irq/chip.c
> +++ b/kernel/irq/chip.c
> @@ -216,10 +216,11 @@ void irq_enable(struct irq_desc *desc)
>  void irq_disable(struct irq_desc *desc)
>  {
>  	irq_state_set_disabled(desc);
> -	if (desc->irq_data.chip->irq_disable) {
> +	if (desc->irq_data.chip->irq_disable)
>  		desc->irq_data.chip->irq_disable(&desc->irq_data);
> -		irq_state_set_masked(desc);
> -	}
> +	else
> +		desc->irq_data.chip->irq_mask(&desc->irq_data);
> +	irq_state_set_masked(desc);
>  }
>  
>  void irq_percpu_enable(struct irq_desc *desc, unsigned int cpu)

Well I hope Thomas knows what this patch does, because I sure don't.

Does it fix a bug?  Does it add a bug?  Does it have any
runtime-observable effects at all?  If so, what are they?

Re: [PATCH] genirq: use irq_mask as fallback for irq_disable.

[Thomas Gleixner]

On Mon, 22 Apr 2013, Andrew Morton wrote:

> On Fri, 19 Apr 2013 15:41:02 +0200 Andreas Fenkart <andreas.fenkart@streamunlimited.com> wrote:
> 
> > This is in line with irq_enable that uses the same fallback.
> > When masked, interrupts are still latched into the status register
> > so when unmasked there is an interrupt straight away.
> > 
> > ...
> >
> > --- a/kernel/irq/chip.c
> > +++ b/kernel/irq/chip.c
> > @@ -216,10 +216,11 @@ void irq_enable(struct irq_desc *desc)
> >  void irq_disable(struct irq_desc *desc)
> >  {
> >  	irq_state_set_disabled(desc);
> > -	if (desc->irq_data.chip->irq_disable) {
> > +	if (desc->irq_data.chip->irq_disable)
> >  		desc->irq_data.chip->irq_disable(&desc->irq_data);
> > -		irq_state_set_masked(desc);
> > -	}
> > +	else
> > +		desc->irq_data.chip->irq_mask(&desc->irq_data);
> > +	irq_state_set_masked(desc);
> >  }
> >  
> >  void irq_percpu_enable(struct irq_desc *desc, unsigned int cpu)
> 
> Well I hope Thomas knows what this patch does, because I sure don't.

I know what it does, but the changelog is completely useless.
 
> Does it fix a bug?  Does it add a bug?  Does it have any
> runtime-observable effects at all?  If so, what are they?

It fixes a state inconsistency. Have to think about observable
effects.

Thanks

	tglx