linux-kernel - Re: [patch 1/2] genirq: Handle NOAUTOEN interrupt setup proper

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Date:   Wed, 31 May 2017 17:18:38 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Marc Zyngier <marc.zyngier@....com>
cc:     LKML <linux-kernel@...r.kernel.org>,
        jeffy <jeffy.chen@...k-chips.com>,
        Brian Norris <briannorris@...omium.org>, dianders@...omium.org,
        tfiga@...omium.org
Subject: Re: [patch 1/2] genirq: Handle NOAUTOEN interrupt setup proper

On Wed, 31 May 2017, Marc Zyngier wrote:
> On 31/05/17 10:58, Thomas Gleixner wrote:
> >  #define __irqd_to_state(d) ACCESS_PRIVATE((d)->common, state_use_accessors)
> > @@ -329,6 +330,11 @@ static inline void irqd_clr_activated(st
> >  	__irqd_to_state(d) &= ~IRQD_ACTIVATED;
> >  }
> >  
> > +static inline bool irqd_is_started_up(struct irq_data *d)
> 
> nit: since we have set/clr_started, consider making this is_started
> (without the up)? Or add the _up to clr/set?

Sure.

> > +{
> > +	return __irqd_to_state(d) & IRQD_IRQ_STARTED_UP;
> > +}
> > +
> >  #undef __irqd_to_state
> >  
> >  static inline irq_hw_number_t irqd_to_hwirq(struct irq_data *d)
> > --- a/kernel/irq/chip.c
> > +++ b/kernel/irq/chip.c
> > @@ -185,37 +185,71 @@ static void irq_state_set_masked(struct
> >  	irqd_set(&desc->irq_data, IRQD_IRQ_MASKED);
> >  }
> >  
> > +static void irq_state_clr_started(struct irq_desc *desc)
> > +{
> > +	irqd_clear(&desc->irq_data, IRQD_IRQ_STARTED_UP);
> > +}
> > +
> > +static void irq_state_set_started(struct irq_desc *desc)
> > +{
> > +	irqd_set(&desc->irq_data, IRQD_IRQ_STARTED_UP);
> > +}
> > +
> >  int irq_startup(struct irq_desc *desc, bool resend)
> >  {
> >  	int ret = 0;
> >  
> > -	irq_state_clr_disabled(desc);
> > +	if (irqd_is_started_up(&desc->irq_data))
> > +		return 0;
> > +
> 
> How about:
> 	if (irqd_is_started_up(&desc->irq_data)) {
> 		irq_enable(desc);
> 		return 0;

Why would we do that? I rather have a WARN_ON() there as this should never
happen.

> > +	/*
> > +	 * This must be called even if the interrupt was never started up,
> > +	 * because the activation can happen before the interrupt is
> > +	 * available for request/startup. It has it's own state tracking so
> > +	 * it's safe to call it unconditonally.
> 
>                                 unconditionally?

Oops.

> >  extern int irq_startup(struct irq_desc *desc, bool resend);
> >  extern void irq_shutdown(struct irq_desc *desc);
> > +extern void irq_enable_or_startup(struct irq_desc *desc);
> >  extern void irq_enable(struct irq_desc *desc);
> >  extern void irq_disable(struct irq_desc *desc);
> >  extern void irq_percpu_enable(struct irq_desc *desc, unsigned int cpu);
> > --- a/kernel/irq/manage.c
> > +++ b/kernel/irq/manage.c
> > @@ -533,7 +533,7 @@ void __enable_irq(struct irq_desc *desc)
> >  			goto err_out;
> >  		/* Prevent probing on this irq: */
> >  		irq_settings_set_noprobe(desc);
> > -		irq_enable(desc);
> > +		irq_enable_or_startup(desc);
> 
> and make this irq_startup(desc, false)?

Ah, now I see where you were heading with that irq_startup()
modification. Makes sense, but let me think about it.

Thanks,

	tglx