linux-kernel - Re: [PATCH v2 1/2] IIO: st_accel_i2c.c: Simplify access to driver data

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Date:   Wed, 4 Jul 2018 08:56:59 +0200 (CEST)
From:   Nikolaus Voss <nikolaus.voss@...wensteinmedical.de>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
cc:     Jonathan Cameron <jic23@...nel.org>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Lorenzo Bianconi <lorenzo.bianconi83@...il.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Xiongfeng Wang <xiongfeng.wang@...aro.org>,
        linux-iio@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/2] IIO: st_accel_i2c.c: Simplify access to driver
 data

On Wed, 4 Jul 2018, Andy Shevchenko wrote:
> On Tue, Jul 3, 2018 at 8:41 AM, Nikolaus Voss
> <nikolaus.voss@...wensteinmedical.de> wrote:
>> Use device_get_match_data API to simplify access to driver data.
>
> ..._data()
>
> But. You actually don't use it below.

It is used, see below.

>
>> Let acpi_device_id table entries point to the same driver data as
>> of_device_id table entries and uniquify access to driver data by using
>> device_get_match_data API.
>
>>  #include <linux/acpi.h>
>>  #include <linux/i2c.h>
>>  #include <linux/iio/iio.h>
>
>> +#include <linux/of_device.h>
>
> (linux/property.h)
>
>> +       match = of_device_get_match_data(&client->dev);
>> +       if (!match)
>> +               match = acpi_device_get_match_data(&client->dev);
>
> What I meant is to simply call
>
> match = device_get_match_data(...);

Ok, this works, thank you. I will prepare a new patch version.

This is where the match data is used:

>
>> +       if (match)
>> +               strlcpy(client->name, match, sizeof(client->name));
>
>

In this driver, match data is used to map DT compatible strings/ ACPI CIDs 
to the key strings (.._ACCEL_DEV_NAME) which are used to identify the 
actual device (and are also used in i2c_device_id table).

Niko