linux-kernel - Re: [PATCH v3 3/4] irqchip: GIC: Convert to EOImode == 1

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Date:	Tue, 25 Aug 2015 18:18:51 +0100
From:	Marc Zyngier <marc.zyngier@....com>
To:	Thomas Gleixner <tglx@...utronix.de>
CC:	Jason Cooper <jason@...edaemon.net>,
	Christoffer Dall <christoffer.dall@...aro.org>,
	Jiang Liu <jiang.liu@...ux.intel.com>,
	Eric Auger <eric.auger@...aro.org>,
	linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
	kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 3/4] irqchip: GIC: Convert to EOImode == 1

Hi Thomas,

On 25/08/15 16:46, Thomas Gleixner wrote:
> On Tue, 25 Aug 2015, Marc Zyngier wrote:
>> +static struct static_key supports_deactivate = STATIC_KEY_INIT_TRUE;
>> +
>>  #ifndef MAX_GIC_NR
>>  #define MAX_GIC_NR	1
>>  #endif
>> @@ -137,6 +140,14 @@ static inline unsigned int gic_irq(struct irq_data *d)
>>  	return d->hwirq;
>>  }
>>  
>> +static inline bool primary_gic_irq(struct irq_data *d)
>> +{
>> +	if (MAX_GIC_NR > 1)
>> +		return irq_data_get_irq_chip_data(d) == &gic_data[0];
>> +
>> +	return true;
>> +}
>> +
>>  /*
>>   * Routines to acknowledge, disable and enable interrupts
>>   */
>> @@ -164,7 +175,14 @@ static void gic_unmask_irq(struct irq_data *d)
>>  
>>  static void gic_eoi_irq(struct irq_data *d)
>>  {
>> -	writel_relaxed(gic_irq(d), gic_cpu_base(d) + GIC_CPU_EOI);
>> +	u32 deact_offset = GIC_CPU_EOI;
>> +
>> +	if (static_key_true(&supports_deactivate)) {
>> +		if (primary_gic_irq(d))
>> +			deact_offset = GIC_CPU_DEACTIVATE;
> 
> I really wonder for the whole series whether you really want all that
> static key dance and extra conditionals in the callbacks instead of
> just using seperate irq chips for the different interrupts.

Hmmm. We definitely could have different irqchips between primary and
secondary controllers indeed. We'd still need a static key for the
gic_handle_irq path though, but that's not too bad.

Let me hack something, and I'll come back to you ;-).

	M.
-- 
Jazz is not dead. It just smells funny...
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