linux-kernel - Re: [Patch Part2 v4 01/31] irqdomain: Introduce new interfaces to support hierarchy irqdomains

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Message-ID: <545B1093.1050403@linux.intel.com>
Date:	Thu, 06 Nov 2014 14:09:23 +0800
From:	Jiang Liu <jiang.liu@...ux.intel.com>
To:	Thomas Gleixner <tglx@...utronix.de>
CC:	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Randy Dunlap <rdunlap@...radead.org>,
	Yinghai Lu <yinghai@...nel.org>,
	Borislav Petkov <bp@...en8.de>,
	Grant Likely <grant.likely@...aro.org>,
	Marc Zyngier <marc.zyngier@....com>,
	Yingjoe Chen <yingjoe.chen@...iatek.com>,
	Jonathan Corbet <corbet@....net>,
	Matthias Brugger <matthias.bgg@...il.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Tony Luck <tony.luck@...el.com>,
	Joerg Roedel <joro@...tes.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	x86@...nel.org, linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org, linux-acpi@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-doc@...r.kernel.org
Subject: Re: [Patch Part2 v4 01/31] irqdomain: Introduce new interfaces to
 support hierarchy irqdomains



On 2014/11/6 7:48, Thomas Gleixner wrote:
> On Tue, 4 Nov 2014, Jiang Liu wrote:
>>  /* Number of irqs reserved for a legacy isa controller */
>>  #define NUM_ISA_INTERRUPTS	16
>> @@ -64,6 +66,16 @@ struct irq_domain_ops {
>>  	int (*xlate)(struct irq_domain *d, struct device_node *node,
>>  		     const u32 *intspec, unsigned int intsize,
>>  		     unsigned long *out_hwirq, unsigned int *out_type);
>> +
>> +#ifdef	CONFIG_IRQ_DOMAIN_HIERARCHY
>> +	/* extended V2 interfaces to support hierarchy irq_domains */
>> +	int (*alloc)(struct irq_domain *d, unsigned int virq,
>> +		     unsigned int nr_irqs, void *arg);
>> +	void (*free)(struct irq_domain *d, unsigned int virq,
>> +		     unsigned int nr_irqs);
>> +	int (*activate)(struct irq_domain *d, struct irq_data *irq_data);
>> +	int (*deactivate)(struct irq_domain *d, struct irq_data *irq_data);
> 
> Why do we have a return value here? Especially the deactivate one
> makes no sense at all.
> 
>> +extern int irq_domain_activate_irq(struct irq_data *irq_data);
>> +extern int irq_domain_deactivate_irq(struct irq_data *irq_data);
> 
> And here.
> 
>> @@ -178,6 +179,7 @@ int irq_startup(struct irq_desc *desc, bool resend)
>>  	irq_state_clr_disabled(desc);
>>  	desc->depth = 0;
>>  
>> +	irq_domain_activate_irq(&desc->irq_data);
> 
> We do not check it and we cannot do here AFAICT.
> 
>>  	if (desc->irq_data.chip->irq_startup) {
>>  		ret = desc->irq_data.chip->irq_startup(&desc->irq_data);
>>  		irq_state_clr_masked(desc);
>> @@ -199,6 +201,7 @@ void irq_shutdown(struct irq_desc *desc)
>>  		desc->irq_data.chip->irq_disable(&desc->irq_data);
>>  	else
>>  		desc->irq_data.chip->irq_mask(&desc->irq_data);
>> +	irq_domain_deactivate_irq(&desc->irq_data);
> 
> Ditto.
> 
> So the return value for irq_domain_deactivate_irq() is silly to begin
> with, but also the return value for irq_domain_activate_irq() does not
> really make sense. We've allocated the resources for the interrupt
> already down the hierarchy chain. So there is no reason why the actual
> activation should fail.
Hi Thomas,
	Fair enough, I have changed them to return void, which also
simplify the implementation. But add one or two BUG_ON()s:)
Regards!
Gerry
> 
> Thanks,
> 
> 	tglx
> 
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