linux-kernel - Re: [PATCH] genirq: Skip chained interrupt trigger configuration if type is IRQ_TYPE

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Date:   Mon, 19 Sep 2016 11:30:24 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Marc Zyngier <marc.zyngier@....com>
cc:     linux-kernel@...r.kernel.org,
        Geert Uytterhoeven <geert@...ux-m68k.org>
Subject: Re: [PATCH] genirq: Skip chained interrupt trigger configuration if
 type is IRQ_TYPE_NONE

On Mon, 19 Sep 2016, Thomas Gleixner wrote:
> On Mon, 19 Sep 2016, Marc Zyngier wrote:
> > On 19/09/16 10:12, Thomas Gleixner wrote:
> > > On Mon, 19 Sep 2016, Marc Zyngier wrote:
> > >>  	if (handle != handle_bad_irq && is_chained) {
> > >> +		unsigned int type = irqd_get_trigger_type(&desc->irq_data);
> > >> +
> > >>  		/*
> > >>  		 * We're about to start this interrupt immediately,
> > >>  		 * hence the need to set the trigger configuration.
> > >> @@ -828,8 +830,10 @@ __irq_do_set_handler(struct irq_desc *desc, irq_flow_handler_t handle,
> > >>  		 * chained interrupt. Reset it immediately because we
> > >>  		 * do know better.
> > >>  		 */
> > >> -		__irq_set_trigger(desc, irqd_get_trigger_type(&desc->irq_data));
> > >> -		desc->handle_irq = handle;
> > >> +		if (type != IRQ_TYPE_NONE) {
> > >> +			__irq_set_trigger(desc, type);
> > >> +			desc->handle_irq = handle;
> > > 
> > > Are you really sure that the handler should only be set when the trigger
> > > type is != NONE? I seriously doubt that this is correct.
> > 
> > The handler has already been set outside of if() statement (at line
> > 819). Here, we only set it again if we've actually called
> > __irq_set_trigger() which could have changed it to something that takes
> > the type into account (handle_level_irq or handle_edge_irq, for example).
> 
> Ah. I'll add a comment...

Bah. There is one already. Reading patches before being awake seems not to
be a brilliant idea.