linux-kernel - Re: [patch 07/16] genirq: Introduce helper irq_domain_set

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Date:	Tue, 18 Nov 2014 21:28:52 +0800
From:	"Yun Wu (Abel)" <wuyun.wu@...wei.com>
To:	Jiang Liu <jiang.liu@...ux.intel.com>
CC:	Thomas Gleixner <tglx@...utronix.de>,
	LKML <linux-kernel@...r.kernel.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Grant Likely <grant.likely@...aro.org>,
	Marc Zyngier <marc.zyngier@....com>,
	Yingjoe Chen <yingjoe.chen@...iatek.com>,
	Yijing Wang <wangyijing@...wei.com>
Subject: Re: [patch 07/16] genirq: Introduce helper irq_domain_set_info()
 to reduce duplicated code

On 2014/11/18 20:38, Jiang Liu wrote:

> On 2014/11/18 19:47, Yun Wu (Abel) wrote:
>> On 2014/11/18 18:03, Thomas Gleixner wrote:
>>
>>> On Tue, 18 Nov 2014, Yun Wu (Abel) wrote:
>>>
>>>> Hi Thomas, Jiang,
>>>> On 2014/11/12 21:43, Thomas Gleixner wrote:
>>>>
>>>>> From: Jiang Liu <jiang.liu@...ux.intel.com>
>>>> [...]
>>>>> +void irq_domain_set_info(struct irq_domain *domain, unsigned int virq,
>>>>> +			 irq_hw_number_t hwirq, struct irq_chip *chip,
>>>>> +			 void *chip_data, irq_flow_handler_t handler,
>>>>> +			 void *handler_data, const char *handler_name)
>>>>> +{
>>>>> +	irq_domain_set_hwirq_and_chip(domain, virq, hwirq, chip, chip_data);
>>>>> +	__irq_set_handler(virq, handler, 0, handler_name);
>>>>> +	irq_set_handler_data(virq, handler_data);
>>>>> +}
>>>>
>>>> When stacked domain enabled, there will be a semantic shift to the linux interrupt
>>>> identifiers. The @virq now delivers much more than before.
>>>> More specifically, now we need both @virq and @domain, rather than only @irq, to
>>>> determine which irq_data we want to configure. And once we configure @irq without
>>>> providing the exact domain, it means we are configuring all the domains related to
>>>> that @irq. So I think this routine just messed all things up.
>>>
>>> You can mess up anything by using an interface in the wrong way. Open
>>> coding will not make that harder.
>>>
>>
>> But what's the correct way to use this interface?
>
> 	It's to be used by interrupt controller drivers to implement
> hierarchy irqdomains.
> 

Each time an interrupt domain calls this, the previous (@handler, @handler_name,
@handler_data) will be overrode. It's because the routines __irq_set_handler()
and irq_set_handler_data() only configure top level (without Marc's fix which is
not ideal). Is this what we really want to see?

Thanks,
	Abel

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