Message-ID: <9aa75234-c391-c61d-d1b6-1d377459b0fe@arm.com>
Date:   Mon, 5 Jun 2017 09:05:24 +0100
From:   Marc Zyngier <marc.zyngier@....com>
To:     Icenowy Zheng <icenowy@...c.io>,
        linux-arm-kernel@...ts.infradead.org, Chen-Yu Tsai <wens@...e.org>
Cc:     devicetree <devicetree@...r.kernel.org>,
        Jason Cooper <jason@...edaemon.net>,
        Mark Brown <broonie@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-sunxi <linux-sunxi@...glegroups.com>,
        Rob Herring <robh+dt@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Lee Jones <lee.jones@...aro.org>,
        Maxime Ripard <maxime.ripard@...e-electrons.com>
Subject: Re: [linux-sunxi] Re: [PATCH v6 2/9] irqchip/sunxi-nmi: add support
 for the NMI in A64 R_INTC

On 05/06/17 08:56, Icenowy Zheng wrote:
> 
> 
> 于 2017年6月5日 GMT+08:00 下午3:53:50, Marc Zyngier <marc.zyngier@....com> 写到:
>> On 05/06/17 06:57, Chen-Yu Tsai wrote:
>>> Hi Marc,
>>>
>>> On Mon, May 22, 2017 at 10:25 PM, Chen-Yu Tsai <wens@...e.org> wrote:
>>>> On Mon, May 22, 2017 at 5:41 PM, Icenowy Zheng <icenowy@...c.io>
>> wrote:
>>>>>
>>>>>
>>>>> 于 2017年5月22日 GMT+08:00 下午5:39:22, Marc Zyngier
>> <marc.zyngier@....com> 写到:
>>>>>> On 18/05/17 08:16, Icenowy Zheng wrote:
>>>>>>> Add support for the newly imported compatible for the A64 R_INTC
>> in
>>>>>>> irq-sunxi-nmi driver.
>>>>>>>
>>>>>>> Signed-off-by: Icenowy Zheng <icenowy@...c.io>
>>>>>>> ---
>>>>>>> Changes in v5:
>>>>>>> - Fix A64 R_INTC compatible.
>>>>>>>
>>>>>>>  drivers/irqchip/irq-sunxi-nmi.c | 13 +++++++++++++
>>>>>>>  1 file changed, 13 insertions(+)
>>>>>>>
>>>>>>> diff --git a/drivers/irqchip/irq-sunxi-nmi.c
>>>>>> b/drivers/irqchip/irq-sunxi-nmi.c
>>>>>>> index 668730c5cb66..5559c1d593bf 100644
>>>>>>> --- a/drivers/irqchip/irq-sunxi-nmi.c
>>>>>>> +++ b/drivers/irqchip/irq-sunxi-nmi.c
>>>>>>> @@ -56,6 +56,12 @@ static struct sunxi_sc_nmi_reg_offs
>> sun9i_reg_offs
>>>>>> = {
>>>>>>>      .enable = 0x04,
>>>>>>>  };
>>>>>>>
>>>>>>> +static struct sunxi_sc_nmi_reg_offs sun50i_reg_offs = {
>>>>>>> +    .ctrl   = 0x0c,
>>>>>>> +    .pend   = 0x10,
>>>>>>> +    .enable = 0x40,
>>>>>>> +};
>>>>>>> +
>>>>>>
>>>>>> Magic values? Even if no #define is provided, a pointer to the
>>>>>> corresponding documentation would be appreciated (assuming
>>>>>> documentation
>>>>>> exists).
>>>>>
>>>>> No documents is available for A64 R_INTC.
>>>>
>>>> No code either. In Allwinner's BSP, the interrupts for the PMICs go
>>>> through the (closed source) OpenRISC firmware, so there's no driver
>>>> for it in the kernel.
>>>>
>>>> The registers line up with the old interrupt controller from the
>> A10,
>>>> but it seems only the NMI interrupt is wired up.
>>>
>>> Is this OK? Or do you want Icenowy to respin a version with defines?
>>
>> Ideally, I'd like to see some #defines, but given that the rest of the
>> file is already littered with hard-coded constants, you might as well
>> do
>> the whole thing in a subsequent patch that I would merge with these two
>> patches.
> 
> Personally I think the values are self-explained (the variable
> name) and used only once in this structure.
> 
> Making defines doesn't make the code more clear.

That's where you're severely misguided. There is plenty of places in the
kernel where constants are used exactly once, and yet they have a
#define. And the reason for this is consistency. We don't deal with raw
values, we deal with named constants.

For you, this code is probably "write-only". Once it works, you'll never
go back to it. On the other hand, I get to maintain it and apply tree
wide changes as necessary. So if the code looks better *to me*, then
that's the way.

Thanks,

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

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