Message-ID: <546B4B7E.5090602@linux.intel.com>
Date: Tue, 18 Nov 2014 21:37:02 +0800
From: Jiang Liu <jiang.liu@linux.intel.com>
Organization: Intel
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To: "Yun Wu (Abel)" <wuyun.wu@huawei.com>
CC: Thomas Gleixner <tglx@linutronix.de>, LKML <linux-kernel@vger.kernel.org>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Grant Likely <grant.likely@linaro.org>,
        Marc Zyngier <marc.zyngier@arm.com>,
        Yingjoe Chen <yingjoe.chen@mediatek.com>,
        Yijing Wang <wangyijing@huawei.com>
Subject: Re: [patch 07/16] genirq: Introduce helper irq_domain_set_info()
 to reduce duplicated code
References: <20141112133941.647950773@linutronix.de> <20141112134120.393705922@linutronix.de> <546B10DA.3040504@huawei.com> <alpine.DEB.2.11.1411181102160.3909@nanos> <546B31D7.6030204@huawei.com> <546B3DCD.9090307@linux.intel.com> <546B4994.7080302@huawei.com>
In-Reply-To: <546B4994.7080302@huawei.com>
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Sender: linux-kernel-owner@vger.kernel.org

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@linux.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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