linux-kernel - Re: [PATCH] i2c: core: helper function to detect slave mode

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Message-ID: <7fdf5d3c-d0ea-ec45-6b18-4573fff6dd11@synopsys.com>
Date:   Mon, 16 Jan 2017 10:32:36 +0000
From:   Luis Oliveira <Luis.Oliveira@...opsys.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Vladimir Zapolskiy <vz@...ia.com>,
        Andy Shevchenko <andy.shevchenko@...il.com>
CC:     Luis Oliveira <Luis.Oliveira@...opsys.com>,
        Wolfram Sang <wsa@...-dreams.de>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Jarkko Nikula <jarkko.nikula@...ux.intel.com>,
        "Mika Westerberg" <mika.westerberg@...ux.intel.com>,
        <linux-i2c@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        <Ramiro.Oliveira@...opsys.com>,
        Joao Pinto <Joao.Pinto@...opsys.com>,
        <CARLOS.PALMINHA@...opsys.com>
Subject: Re: [PATCH] i2c: core: helper function to detect slave mode

On 12-Jan-17 17:01, Andy Shevchenko wrote:
> On Sat, 2017-01-07 at 03:24 +0200, Vladimir Zapolskiy wrote:
>> On 01/07/2017 02:19 AM, Andy Shevchenko wrote:
>>> On Sat, Jan 7, 2017 at 1:43 AM, Vladimir Zapolskiy <vz@...ia.com>
>>> wrote:
>>>> On 01/07/2017 12:45 AM, Andy Shevchenko wrote:
> 
>>>>> +             }
>>>>>>> +     } else if (IS_BUILTIN(CONFIG_ACPI) &&
>>>>>>> ACPI_HANDLE(dev)) {
>>>>>>> +             dev_dbg(dev, "ACPI slave is not supported
>>>>>>> yet\n");
>>>>>>> +     }
>>>>>>
>>>>>> If so, then it might be better to drop else-if stub for now.
>>>>>
>>>>> Please, don't.
>>>>>
>>>>
>>>> Why do you ask for this stub to be added?
>>>
>>> 1. Exactly the reason you asked above. Here is the code which has
>>> built differently on different platforms. x86 usually is not using
>>> CONFIG_OF, ARM doesn't ACPI (versus ARM64). Check GPIO library for
>>> existing examples.
>>
>> From the context by the stub I mean dev_dbg() in
>> i2c_slave_mode_detect()
>> function, I don't see a connection to GPIO library, please clarify.
> 
> I agree that is not good proof for using IS_ENABLED/IS_BUILTIN macro.

I can prepare a V3 and remove it if that's the decision.

> 
>>> 2. We might add that support later, but here is again, just no-op.
>>>
>>> So, what is your strong argument here against that?
>>
>> When the support is ready for ACPI case, you'll remove the added
>> dev_dbg(), and I don't see a good point by adding it temporarily.
> 
> It would remind me to look at it at some point.
> 
>> What is wrong with the approach of adding the ACPI case handling
>> branch when it is ready and remove any kind of stubs right now?
> 
> I will not object. Here is maintainer, let him speak.
> 
>> On ACPI platforms the function returns 'false' always, will the
>> function work correctly (= corresponding to its description) as is?
> 
> Yes.
>