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

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Message-ID: <546B4B7E.5090602@linux.intel.com>
Date:	Tue, 18 Nov 2014 21:37:02 +0800
From:	Jiang Liu <jiang.liu@...ux.intel.com>
To:	"Yun Wu (Abel)" <wuyun.wu@...wei.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 21:28, Yun Wu (Abel) wrote:
> 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?
Hi Yun,
	There are different interfaces for different purposes.
irq_domain_set_hwirq_and_chip() sets hwirq, irq_chip and irq_chip_data.
irq_domain_set_info() sets handler and handler_data in addition to
irq_domain_set_hwirq_and_chip().
	Which irqdomain to call irq_domain_set_info() to set irq_handler
is determined by the interrupt hierarchy. And at least on irqdomain in
the hierarchy must set flow handler for the irq.
Thanks!
Gerry

> 
> Thanks,
> 	Abel
> 
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