linux-kernel - Re: [PATCH v3 1/3] iio: add struct declarations for iio types

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Date:   Mon, 28 Nov 2022 14:48:48 +0100
From:   Michael Riesch <michael.riesch@...fvision.net>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Gerald Loacker <gerald.loacker@...fvision.net>
Cc:     linux-iio@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, Jonathan Cameron <jic23@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Jakob Hauser <jahau@...ketmail.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Nikita Yushchenko <nikita.yoush@...entembedded.com>
Subject: Re: [PATCH v3 1/3] iio: add struct declarations for iio types

Hi Gerald, Andy,

On 11/28/22 14:27, Andy Shevchenko wrote:
> On Mon, Nov 28, 2022 at 01:18:04PM +0100, Gerald Loacker wrote:
>> Am 25.11.2022 um 12:01 schrieb Andy Shevchenko:
>>> On Fri, Nov 25, 2022 at 12:45:06PM +0200, Andy Shevchenko wrote:
>>>> On Fri, Nov 25, 2022 at 09:35:24AM +0100, Gerald Loacker wrote:
> 
> ...
> 
>>>>> +struct iio_val_int_plus_micro {
>>>>> +	int val_int;
>>>>> +	int val_micro;
>>>>> +};
>>>
>>> Thinking more about naming, why not drop val_ completely?
>>>
>>> 	int integer;
>>> 	int micro;
>>>
>>> ?
>>
>> Yes, this sounds good to me. I think of adding only
>>
>> 	typedef struct {
>> 		int integer;
>> 		int micro;
>> 	} iio_val_int_plus_micro;

I think we actually want

struct iio_val_int_plus_micro {
	int integer;
	int micro;
};

here, right?

>> for now, and one can add similar structures when needed, like
>>
>> 	typedef struct {
>> 		int integer;
>> 		int nano;
>> 	} iio_val_int_plus_nano;

+1 for introducing things when they are actually used.

> It's a rule to use _t for typedef:s in the kernel. That's why
> I suggested to leave struct definition and only typedef the same structures
> (existing) to new names (if needed).

Andy, excuse our ignorance but we are not sure how this typedef approach
is supposed to look like...

>> or
> 
>> 	typedef iio_val_int_plus_micro iio_val_int_plus_micro_db;

... because

#include <stdio.h>

struct iio_val_int_plus_micro {
	int integer;
	int micro;
};

typedef iio_val_int_plus_micro iio_val_int_plus_micro_db;

int main()
{
  struct iio_val_int_plus_micro a = { .integer = 100, .micro = 10, };
  struct iio_val_int_plus_micro_db b = { .integer = 20, .micro = 10, };
  return 0;
}

won't compile.

> This is better as explained above.
> 
>> If you think it's better to add them all, I can do that, of course.

Anyway, seeing that only struct iio_val_int_plus_micro is used at the
moment, I believe the best path forward is to introduce only this struct
and move on.

Best regards,
Michael

>>>>> +struct iio_val_int_plus_nano {
>>>>> +	int val_int;
>>>>> +	int val_nano;
>>>>> +};
>>>>> +
>>>>> +struct iio_val_int_plus_micro_db {
>>>>> +	int val_int;
>>>>
>>>> 	int val_int_db; ?
>>>>
>>>>> +	int val_micro_db;
>>>>> +};
>>>>
>>>> Actually why can't we simply do
>>>>
>>>> typedef iio_val_int_plus_micro_db iio_val_int_plus_micro;
>>>>
>>>> ?
>