linux-kernel - Re: [PATCH v2 1/1] iio: humidity: hdc100x: add manufacturer and device ID cehck

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Date:   Wed, 27 Jul 2022 18:40:37 +0800
From:   Potin Lai <potin.lai.pt@...il.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Jonathan Cameron <jic23@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Patrick Williams <patrick@...cx.xyz>,
        Potin Lai <potin.lai@...ntatw.com>,
        linux-iio <linux-iio@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/1] iio: humidity: hdc100x: add manufacturer and
 device ID cehck


On 7/27/22 18:00, Andy Shevchenko wrote:
> On Wed, Jul 27, 2022 at 8:46 AM Potin Lai <potin.lai.pt@...il.com> wrote:
>> Add manufacturer and device ID checking during probe, and skip the
>> checking if chip model not supported.
>>
>> Supported:
>> - HDC1000
>> - HDC1010
>> - HDC1050
>> - HDC1080
>>
>> Not supported:
>> - HDC1008
> Thanks for an update, my comments below.
>
> ...
>
>> +       const struct of_device_id *match;
> Don't you have a compiler warning? Always compile your code with `make W=1`
>
> ...

You are correct, I will remove this unused variable.

>> +       data = device_get_match_data(&client->dev);
>> +       if (data) {
> This check is redundant. Too much protective programming. Just oblige
> that matched ID has to always have an associated data.
Is it guaranteed that device_get_match_data will not return NULL? I find some examples in other drivers, all of them have a check on returned data.

Will it be more appropriate if I move device_get_match_data to probe function, and return EINVAL when we get a NULL pointer from device_get_match_data?

>> +               if (!data->support_mfr_check)
>> +                       return true;
>> +       }
> ...
>
>> -       .probe = hdc100x_probe,
>> +       .probe_new = hdc100x_probe,
> Make this a separate patch before the presented one.
>
got it, will move this into a separate patch in next version.

thanks,
Potin