linux-kernel - Re: [PATCH v5 04/14] spmi: pmic-arb: convert to v2 irq interfaces to support hierarchical IRQ chips

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Date:   Fri, 18 Jan 2019 07:27:16 -0500
From:   Brian Masney <masneyb@...tation.org>
To:     Marc Zyngier <marc.zyngier@....com>
Cc:     linus.walleij@...aro.org, sboyd@...nel.org,
        bjorn.andersson@...aro.org, andy.gross@...aro.org,
        shawnguo@...nel.org, dianders@...omium.org,
        linux-gpio@...r.kernel.org, nicolas.dechesne@...aro.org,
        niklas.cassel@...aro.org, david.brown@...aro.org,
        robh+dt@...nel.org, mark.rutland@....com, thierry.reding@...il.com,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH v5 04/14] spmi: pmic-arb: convert to v2 irq interfaces to
 support hierarchical IRQ chips

Hi Marc,

On Thu, Jan 17, 2019 at 11:22:59AM +0000, Marc Zyngier wrote:
> > -static int qpnpint_irq_domain_map(struct irq_domain *d,
> > -				  unsigned int virq,
> > -				  irq_hw_number_t hwirq)
> > -{
> > -	struct spmi_pmic_arb *pmic_arb = d->host_data;
> >  
> > +static void qpnpint_irq_domain_map(struct spmi_pmic_arb *pmic_arb,
> > +				   struct irq_domain *domain, unsigned int virq,
> > +				   irq_hw_number_t hwirq)
> > +{
> >  	dev_dbg(&pmic_arb->spmic->dev, "virq = %u, hwirq = %lu\n", virq, hwirq);
> >  
> > -	irq_set_chip_and_handler(virq, &pmic_arb_irqchip, handle_level_irq);
> > -	irq_set_chip_data(virq, d->host_data);
> > -	irq_set_noprobe(virq);
> > +	irq_domain_set_info(domain, virq, hwirq, &pmic_arb_irqchip, pmic_arb,
> > +			    handle_level_irq, NULL, NULL);
> 
> I understand you haven't changed the existing semantic here by always
> setting the handler to handle_level_irq. But is that guaranteed to
> always be the case? See below.
> 
> > +}
> > +
> > +static int qpnpint_irq_domain_alloc(struct irq_domain *domain,
> > +				    unsigned int virq, unsigned int nr_irqs,
> > +				    void *data)
> > +{
> > +	struct spmi_pmic_arb *pmic_arb = domain->host_data;
> > +	struct irq_fwspec *fwspec = data;
> > +	irq_hw_number_t hwirq;
> > +	unsigned int type;
> > +	int ret, i;
> > +
> > +	ret = qpnpint_irq_domain_translate(domain, fwspec, &hwirq, &type);
> 
> Here, you extract the trigger from DT.
> 
> > +	if (ret)
> > +		return ret;
> > +
> > +	for (i = 0; i < nr_irqs; i++)
> > +		qpnpint_irq_domain_map(pmic_arb, domain, virq + i, hwirq + i);
> 
> Shouldn't you propagate it into the mapping function so that the handler
> can be selected accordingly? Or does the interrupt controller convert
> edge signals to level somehow?

qpnpint_irq_set_type() calls irq_set_handler_locked() to set the hander
to be either handle_edge_irq() or handle_level_irq(). So the handler is
initially setup incorrectly in some cases, but then setup correctly (via
__irq_set_trigger) when __setup_irq() is called by
request_threaded_irq().

It looks like that this will cause problems with shared IRQs to work as
expected.

I can rework this code and get this fixed.

Brian