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From: =?iso-8859-1?Q?M=E5ns_Rullg=E5rd?= <mans@mansr.com>
To: Marc Gonzalez <marc_gonzalez@sigmadesigns.com>
Cc: Doug Berger <opendmb@gmail.com>, Thomas Gleixner <tglx@linutronix.de>,
        Marc Zyngier <marc.zyngier@arm.com>,
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        Mason <slash.tmp@free.fr>
Subject: Re: [PATCH v3] irqchip/tango: Don't use incorrect irq_mask_ack callback
References: <20170719190734.18566-1-opendmb@gmail.com>
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        <7a51555f-8191-9ebd-1f30-7c20f6db9d3f@sigmadesigns.com>
        <8d29fec9-35b8-c33b-3091-3e9a51c99ed7@gmail.com>
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        <6f0092f7-692f-4a15-1d95-40f4e59c8585@sigmadesigns.com>
Date: Tue, 25 Jul 2017 14:29:20 +0100
In-Reply-To: <6f0092f7-692f-4a15-1d95-40f4e59c8585@sigmadesigns.com> (Marc
        Gonzalez's message of "Tue, 25 Jul 2017 15:26:40 +0200")
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Marc Gonzalez <marc_gonzalez@sigmadesigns.com> writes:

> On 25/07/2017 15:16, Måns Rullgård wrote:
>
>> What happened to the patch adding the proper combined function?
>
> It appears you're not CCed on v2.
>
> https://patchwork.kernel.org/patch/9859799/
>
> Doug wrote:
>> Yes, you understand correctly.  The irq_mask_ack method is entirely
>> optional and I assume that is why this issue went undetected for so
>> long; however, it is slightly more efficient to combine the functions
>> (even if the ack is unnecessary) which is why I chose to do so for my
>> changes to the irqchip-brcmstb-l2 driver where I first discovered this
>> issue.  How much value the improved efficiency has is certainly
>> debatable, but interrupt handling is one area where people might care
>> about such a small difference.  As the irqchip-tango driver maintainer
>> you are welcome to decide whether or not the irq_mask_ack method makes
>> sense to you.
>
> My preference goes to leaving the irq_mask_ack callback undefined,
> and let the irqchip framework use irq_mask and irq_ack instead.

Why would you prefer the less efficient way?

-- 
Måns Rullgård