Message-ID: <54648C95.6020704@arm.com>
Date: Thu, 13 Nov 2014 10:48:53 +0000
From: Marc Zyngier <marc.zyngier@arm.com>
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To: Jiang Liu <jiang.liu@linux.intel.com>,
        Yingjoe Chen <yingjoe.chen@mediatek.com>
CC: Thomas Gleixner <tglx@linutronix.de>, LKML <linux-kernel@vger.kernel.org>,
        Bjorn Helgaas <bhelgaas@google.com>,
        "grant.likely@linaro.org" <grant.likely@linaro.org>,
        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> <1415872649.17958.37.camel@mtksdaap41> <54648138.2070900@linux.intel.com>
In-Reply-To: <54648138.2070900@linux.intel.com>
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Sender: linux-kernel-owner@vger.kernel.org

On 13/11/14 10:00, Jiang Liu wrote:
> On 2014/11/13 17:57, Yingjoe Chen wrote:
>> On Wed, 2014-11-12 at 13:43 +0000, Thomas Gleixner wrote:
>>> Index: tip/kernel/irq/irqdomain.c
>>> ===================================================================
>>> --- tip.orig/kernel/irq/irqdomain.c
>>> +++ tip/kernel/irq/irqdomain.c
>>> @@ -882,6 +882,16 @@ int irq_domain_set_hwirq_and_chip(struct
>>>  	return 0;
>>>  }
>>>  
>>> +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);
>>> +}
>>> +
>>
>> Hi,
>>
>> While trying to use this function, I'm not sure about its interface.
>> This function have 8 parameters but only save 3 function calls. After
>> checking uses in Jiang's original patch, I think this make code harder
>> to understand.
> Hi Joe,
> 	It's true, but we also want to reduce duplicated code:(

I'm in two minds about this one.

Yes, it looks horrible (to be fair, I hate anything that has more than 3
or 4 parameters, because I can never remember what they're for).

On the other hand, it gives you a nice check-point in your code, with
all the bits you need to set, or at least consider. Because it depends
on so many things that you may have to construct/obtain, you quickly
realize that there is not that many locations in your stack that fits
these requirements. Yes, this a twisted reasoning.

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...

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