Message-ID: <546B4994.7080302@huawei.com>
Date: Tue, 18 Nov 2014 21:28:52 +0800
From: "Yun Wu (Abel)" <wuyun.wu@huawei.com>
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To: Jiang Liu <jiang.liu@linux.intel.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>
In-Reply-To: <546B3DCD.9090307@linux.intel.com>
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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?

Thanks,
	Abel

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