linux-kernel - Re: [RFC PATCH 1/6] DRIVERS: IRQCHIP: IRQ-GIC: Add support for routable irqs

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Message-ID: <5268F4B1.30203@ti.com>
Date:	Thu, 24 Oct 2013 15:51:37 +0530
From:	Sricharan R <r.sricharan@...com>
To:	Thomas Gleixner <tglx@...utronix.de>
CC:	<linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>,
	<linux-doc@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-omap@...r.kernel.org>, <linus.walleij@...aro.org>,
	<santosh.shilimkar@...com>, <linux@....linux.org.uk>,
	<tony@...mide.com>, <rnayak@...com>, <marc.zyngier@....com>,
	<grant.likely@...aro.org>, <rob.herring@...xeda.com>,
	<mark.rutland@....com>
Subject: Re: [RFC PATCH 1/6] DRIVERS: IRQCHIP: IRQ-GIC: Add support for routable
 irqs

Hi Thomas,

Thanks a lot for reviewing this.

On Thursday 24 October 2013 02:42 PM, Thomas Gleixner wrote:
> On Mon, 30 Sep 2013, Sricharan R wrote:
>> diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c
>> index 1760ceb..c5778ab 100644
>> --- a/drivers/irqchip/irq-gic.c
>> +++ b/drivers/irqchip/irq-gic.c
>> @@ -72,6 +72,8 @@ struct gic_chip_data {
>>  
>>  static DEFINE_RAW_SPINLOCK(irq_controller_lock);
>>  
>> +const struct irq_domain_ops *gic_routable_irq_domain_ops;
>> +
>>  /*
>>   * The GIC mapping of CPU interfaces does not necessarily match
>>   * the logical CPU numbering.  Let's use a mapping as returned
>> @@ -675,11 +677,26 @@ static int gic_irq_domain_map(struct irq_domain *d, unsigned int irq,
>>  		irq_set_chip_and_handler(irq, &gic_chip,
>>  					 handle_fasteoi_irq);
>>  		set_irq_flags(irq, IRQF_VALID | IRQF_PROBE);
>> +
>> +		if (gic_routable_irq_domain_ops &&
>> +		    gic_routable_irq_domain_ops->map)
>> +			gic_routable_irq_domain_ops->map(d, irq, hw);
> Shudder. Why are you sprinkling these if (ops && ops->fun)
> conditionals all over the place instead of having a default ops
> implementation which handles the non crossbar case by proper empty
> functions. That code is not on a hot path so it does not matter at
> all.
>
 Ok, Understand. Will add default ops to avoid these checks.
>>  	}
>>  	irq_set_chip_data(irq, d->host_data);
>>  	return 0;
>>  }
>>  
>> +static void gic_irq_domain_unmap(struct irq_domain *d, unsigned int irq)
>> +{
>> +	irq_hw_number_t hw = irq_get_irq_data(irq)->hwirq;
>> +
>> +	if (hw > 32) {
> Groan. This wants to be in the ops->unmap function. It's not related
> to the GIC core code.
 Ok, will move this to unmap ops of the crossbar.
>> +		if (gic_routable_irq_domain_ops &&
>> +		    gic_routable_irq_domain_ops->unmap)
>> +			gic_routable_irq_domain_ops->unmap(d, irq);
>> +	}
>> +}
>> +
>>  static int gic_irq_domain_xlate(struct irq_domain *d,
>>  				struct device_node *controller,
>>  				const u32 *intspec, unsigned int intsize,
>> @@ -694,8 +711,15 @@ static int gic_irq_domain_xlate(struct irq_domain *d,
>>  	*out_hwirq = intspec[1] + 16;
>>  
>>  	/* For SPIs, we need to add 16 more to get the GIC irq ID number */
>> -	if (!intspec[0])
>> -		*out_hwirq += 16;
>> +	if (!intspec[0]) {
>> +		if (gic_routable_irq_domain_ops &&
>> +		    gic_routable_irq_domain_ops->xlate)
>> +			*out_hwirq = gic_routable_irq_domain_ops->xlate(d,
>> +						controller, intspec, intsize,
>> +						out_hwirq, out_type);
>> +		else
>> +			*out_hwirq += 16;
>> +	}
> So if you have a default xlate ops implementation then this boils down to
>
>       if (!intspec[0])
> 		*out_hwirq = routing_ops->xlate()
>
> And the default (non crossbar) implementation would be:
>
>     	return *out_hwirq + 16;
>     
 Ok. This is better. Will change here.


Regards,
 Sricharan
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