Subject: Re: [PATCH] gpio: thunderx: select IRQ_DOMAIN_HIERARCHY instead of
 depends on
To: Masahiro Yamada <yamada.masahiro@socionext.com>,
        David Daney <ddaney@caviumnetworks.com>
Cc: linux-gpio@vger.kernel.org, David Daney <david.daney@cavium.com>,
        Linus Walleij <linus.walleij@linaro.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
References: <1504662052-12478-1-git-send-email-yamada.masahiro@socionext.com>
 <32679e9c-7ad7-a632-4842-6e8e8b820d26@caviumnetworks.com>
 <CAK7LNAQeRZZTrX-aOkJ3u+69ZG3+Tgsm=TbKyNb-aqp9=F3Csw@mail.gmail.com>
From: David Daney <ddaney@caviumnetworks.com>
Message-ID: <8cfd9a26-39d9-6c1d-3414-e0f5f3123ced@caviumnetworks.com>
Date: Wed, 6 Sep 2017 10:36:06 -0700
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On 09/05/2017 09:20 PM, Masahiro Yamada wrote:
> Hi David,
> 
> 
> 2017-09-06 11:09 GMT+09:00 David Daney <ddaney@caviumnetworks.com>:
>> On 09/05/2017 06:40 PM, Masahiro Yamada wrote:
>>>
>>> IRQ_DOMAIN_HIERARCHY is not user-configurable, but supposed to be
>>> selected by drivers that need IRQ domain hierarchy support.
>>>
>>> GPIO_THUNDERX is the only user of "depends on IRQ_DOMAIN_HIERARCHY".
>>> This means, we can not enable GPIO_THUNDERX unless other drivers
>>> select IRQ_DOMAIN_HIERARCHY elsewhere.  This is odd.  Flip the logic.
>>>
>>> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
>>
>>
>> IRQ_DOMAIN_HIERARCHY is set as a result of ARCH_THUNDER (this SoC hardware),
>> so it actually works as-is.
> 
> 
> Right, ARCH_THUNDER does not select it directly,
> but does it indirectly.  (this is not so clear...)
> 
> ARCH_THUNDER  -> ARM64 -> ARM_GIC -> IRQ_DOMAIN_HIERARCHY
> 
> 
> 
>>   That said, this looks like a reasonable
>> improvement, and will allow the COMPILE_TEST to enable it, so...
>>
>> Acked-by: David Daney <david.daney@cavium.com>
> 
> 
> BTW, I could not understand your intention of
> (64BIT && COMPILE_TEST)
> 

The driver uses readq()/writeq(), which are not available in some 32BIT 
kernels.  So to ensure that it can build without error we depend on 
64BIT as a proxy for the availability of readq()/writeq()


David