Re: [RFC PATCH] genirq: Avoid unnecessary low level irq function calls

[jeffy]

Hi Thomas,

thanx for your comments.

On 06/26/2017 04:20 PM, Thomas Gleixner wrote:
> Jeffy,
>
> On Mon, 26 Jun 2017, Jeffy Chen wrote:
> >   void irq_enable(struct irq_desc *desc)
> >   {
> > -	irq_state_clr_disabled(desc);
> > -	if (desc->irq_data.chip->irq_enable)
> > -		desc->irq_data.chip->irq_enable(&desc->irq_data);
> > -	else
> > -		desc->irq_data.chip->irq_unmask(&desc->irq_data);
> > -	irq_state_clr_masked(desc);
> > +	if (irqd_is_started(&desc->irq_data) &&
> > +	    !irqd_irq_disabled(&desc->irq_data)) {
> > +		unmask_irq(desc);
>
> I'm having a hard time to understand the logic here.
>
>      if (started && !disabled)
>      	unmask()
>
> That does not make any sense. If you need that to work around a state
> inconsistency then it needs to be addressed there and not worked around
> here.
right, we already set disabled state in desc_set_defaults, so the 
disabled state should be consistency here. so just
if(!disabled)
  unmask()
else
  enable()
?

and i saw we didn't set masked state in desc_set_defaults, i'll send a 
patch for that, and remove unmask_irq's started check too.
> > +	} else {
> > +		irq_state_clr_disabled(desc);
> > +		if (desc->irq_data.chip->irq_enable) {
> > +			desc->irq_data.chip->irq_enable(&desc->irq_data);
> > +			irq_state_clr_masked(desc);
> > +		} else {
> > +			unmask_irq(desc);
> > +		}
> > +	}
> >   }
> >
> >   static void __irq_disable(struct irq_desc *desc, bool mask)
> >   {
> > -	irq_state_set_disabled(desc);
> > -	if (desc->irq_data.chip->irq_disable) {
> > -		desc->irq_data.chip->irq_disable(&desc->irq_data);
> > -		irq_state_set_masked(desc);
> > -	} else if (mask) {
> > -		mask_irq(desc);
> > +	if (irqd_irq_disabled(&desc->irq_data)) {
> > +		if (mask)
> > +			mask_irq(desc);
> > +	} else {
> > +		irq_state_set_disabled(desc);
> > +		if (desc->irq_data.chip->irq_disable) {
> > +			desc->irq_data.chip->irq_disable(&desc->irq_data);
> > +			irq_state_set_masked(desc);
> > +		} else if (mask) {
> > +			mask_irq(desc);
> > +		}
> >   	}
> >   }
> >
> > @@ -311,18 +322,21 @@ void irq_percpu_disable(struct irq_desc *desc, unsigned int cpu)
> >
> >   static inline void mask_ack_irq(struct irq_desc *desc)
> >   {
> > -	if (desc->irq_data.chip->irq_mask_ack)
> > +	if (desc->irq_data.chip->irq_mask_ack) {
> >   		desc->irq_data.chip->irq_mask_ack(&desc->irq_data);
> > -	else {
> > -		desc->irq_data.chip->irq_mask(&desc->irq_data);
> > +		irq_state_set_masked(desc);
> > +	} else {
> > +		mask_irq(desc);
> >   		if (desc->irq_data.chip->irq_ack)
> >   			desc->irq_data.chip->irq_ack(&desc->irq_data);
> >   	}
> > -	irq_state_set_masked(desc);
> >   }
> >
> >   void mask_irq(struct irq_desc *desc)
> >   {
> > +	if (irqd_irq_masked(&desc->irq_data))
> > +		return;
> > +
> >   	if (desc->irq_data.chip->irq_mask) {
> >   		desc->irq_data.chip->irq_mask(&desc->irq_data);
> >   		irq_state_set_masked(desc);
> > @@ -331,6 +345,10 @@ void mask_irq(struct irq_desc *desc)
> >
> >   void unmask_irq(struct irq_desc *desc)
> >   {
> > +	if (irqd_is_started(&desc->irq_data) &&
> > +	    !irqd_irq_masked(&desc->irq_data))
> > +		return;
>
> Ditto.
>
> Thanks,
>
> 	tglx