linux-kernel - Re: [PATCH v4 6/6] gpio: uniphier: add UniPhier GPIO controller driver

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Message-ID: <CAK7LNARwusK2i2mp7LE4AW28oYs81tWxgXG7pgBa-hu=2ZTW7A@mail.gmail.com>
Date:   Sat, 9 Sep 2017 00:14:45 +0900
From:   Masahiro Yamada <yamada.masahiro@...ionext.com>
To:     Rob Herring <robh+dt@...nel.org>
Cc:     Marc Zyngier <marc.zyngier@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Linus Walleij <linus.walleij@...aro.org>,
        "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
        Jassi Brar <jaswinder.singh@...aro.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        Jason Cooper <jason@...edaemon.net>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        David Daney <david.daney@...ium.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Mark Rutland <mark.rutland@....com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v4 6/6] gpio: uniphier: add UniPhier GPIO controller driver

Hi Rob,


2017-09-08 4:41 GMT+09:00 Rob Herring <robh+dt@...nel.org>:
> On Thu, Sep 7, 2017 at 6:42 AM, Masahiro Yamada
> <yamada.masahiro@...ionext.com> wrote:
>> This GPIO controller device is used on UniPhier SoCs.
>>
>> It also serves as an interrupt controller, but interrupt signals are
>> just delivered to the parent irqchip without any latching or OR'ing.
>> This is implemented by using hierarchy IRQ domain.
>>
>> Implementation note:
>> Unfortunately, the IRQ mapping from this controller to the parent is
>> random. (48, 49, ..., 63, 154, 155, ...)
>> If "interrupts" property is used, IRQ resources may be statically
>> allocated when platform devices are populated from DT.  This can be
>> a problem for the hierarchy IRQ domain because IRQ allocation must
>> happen from the outer-most domain up to the root domain in order to
>> build up the stacked IRQ.  (https://lkml.org/lkml/2017/7/6/758)
>> Solutions to work around it could be to hard-code parent hwirqs or
>> to invent a driver-specific DT property.
>>
>> Here, the new API irq_domain_push_irq() was merged by v4.14-rc1.
>> It allows to add irq_data to the existing hierarchy.  It will help
>> to make this driver work whether the parent has already initialized
>> the hierarchy or not.
>>
>> Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>
>> ---
>>
>> Changes in v4:
>>   - Add COMPILE_TEST and select IRQ_DOMAIN_HIERARCHY
>>   - Reimplement irqchip part by using irq_domain_push_irq()
>>
>> Changes in v3:
>>   - Add .irq_set_affinity() hook
>>   - Use irq_domain_create_hierarchy() instead of legacy
>>     irq_domain_add_hierarchy()
>>
>> Changes in v2:
>>   - Remove +32 offset for parent interrupts to follow the GIC
>>     binding convention
>>   - Let uniphier_gpio_irq_alloc() fail if nr_irqs != 1
>>   - Allocate gpio_chip statically because just one instance is
>>     supported
>>   - Fix suspend and resume hooks
>>
>>  .../devicetree/bindings/gpio/gpio-uniphier.txt     |  43 ++
>
> What happened to my ack? One line here more that before, but I'm not
> going to diff your patches for you.

I changed the binding for this version.
It includes a new one you have not acked yet.

Maybe I was too worried about it.


> BTW, it is preferred to split bindings to a separate patch.

I will do so next time.



-- 
Best Regards
Masahiro Yamada