linux-kernel - Re: [PATCH 2/2] i2c: add support for Socionext SynQuacer I2C controller

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Date:   Wed, 21 Feb 2018 20:54:16 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Ard Biesheuvel <ard.biesheuvel@...aro.org>
Cc:     Wolfram Sang <wsa@...-dreams.de>, Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        linux-i2c <linux-i2c@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arm Mailing List <linux-arm-kernel@...ts.infradead.org>,
        Jassi Brar <jassisinghbrar@...il.com>
Subject: Re: [PATCH 2/2] i2c: add support for Socionext SynQuacer I2C controller

On Wed, Feb 21, 2018 at 8:20 PM, Ard Biesheuvel
<ard.biesheuvel@...aro.org> wrote:
> On 20 February 2018 at 19:39, Andy Shevchenko <andy.shevchenko@...il.com> wrote:
>> On Tue, Feb 20, 2018 at 8:04 PM, Ard Biesheuvel
>> <ard.biesheuvel@...aro.org> wrote:
>>> On 20 February 2018 at 14:02, Andy Shevchenko <andy.shevchenko@...il.com> wrote:

>>>>> +               ret = device_property_read_u32(&pdev->dev,
>>>>> +                                              "socionext,pclk-rate",
>>>>> +                                              &i2c->clkrate);
>>>>
>>>> I suppose for ACPI we just register a fixed rate clock and use it in
>>>> the driver in the same way as in OF case.
>>>> I guess at some point we even can provide a generic clock provider for
>>>> ACPI based on rate property.
>>
>>> Is there a question here? Do you want me to change anything?
>>
>> Is it opener for discussion. At least in the drivers we have done for
>> x86 we do the way I described.
>>
>> See, for example, drivers/mfd/intel-lpss.c

> OK, I see what you mean now. But for this driver, creating a fixed
> rate clock with no controls whatsoever, only to interrogate it for its
> rate (which we retrieved from the ACPI device node in the first place)
> seems rather pointless to me. Am I missing something here?

Somehow you are right. That's why I'm thinking that we need to provide
a generic clock provider for such cases.
It's really not a driver business to know the details of resource provider.

-- 
With Best Regards,
Andy Shevchenko