linux-kernel - Re: [PATCH v2 1/5] iio: adc: ad7192: use devm_regulator_get_enable_read

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Date: Mon, 17 Jun 2024 17:10:23 +0300
From: Alisa-Dariana Roman <alisadariana@...il.com>
To: David Lechner <dlechner@...libre.com>
Cc: Jonathan Cameron <jic23@...nel.org>,
 Marcelo Schmitt <marcelo.schmitt1@...il.com>, Nuno Sá
 <nuno.sa@...log.com>, Michael Hennerich <Michael.Hennerich@...log.com>,
 Mark Brown <broonie@...nel.org>, Liam Girdwood <lgirdwood@...il.com>,
 linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/5] iio: adc: ad7192: use
 devm_regulator_get_enable_read_voltage

On 17.06.2024 16:48, David Lechner wrote:
> On 6/17/24 8:38 AM, Alisa-Dariana Roman wrote:
>> On 17.06.2024 16:22, David Lechner wrote:
>>> On Mon, Jun 17, 2024 at 4:35 AM Alisa-Dariana Roman
>>> <alisadariana@...il.com> wrote:
>>>>
>>>> On 15.06.2024 15:08, Jonathan Cameron wrote:
>>>>> On Wed, 12 Jun 2024 16:03:05 -0500
>>>>> David Lechner <dlechner@...libre.com> wrote:
>>>>>
>>>>>> This makes use of the new devm_regulator_get_enable_read_voltage()
>>>>>> function to reduce boilerplate code.
>>>>>>
>>>>>> Error messages have changed slightly since there are now fewer places
>>>>>> where we print an error. The rest of the logic of selecting which
>>>>>> supply to use as the reference voltage remains the same.
>>>>>>
>>>>>> Also 1000 is replaced by MILLI in a few places for consistency.
>>>>>>
>>>>>> Signed-off-by: David Lechner <dlechner@...libre.com>
>>>>>
>>>>> Complicated bit of code, but seems correct.
>>>>> However, it crossed with Alisa-Dariana switching adding a
>>>>> struct device *dev = &spi->dev to probe() that I picked up earlier
>>>>> today.
>>>>>
>>>>> I could unwind that but given Alisa-Dariana has a number of
>>>>> other patches on this driver in flight, I'd like the two of you
>>>>> to work out the best resolution between you.  Maybe easiest option
>>>>> is that Alisa-Dariana sends this a first patch of the next
>>>>> series I should pick up.
>>>>>
>>>>> Thanks,
>>>>>
>>>>> Jonathan
>>>> I will add this patch to my series and send it shortly.
>>>>
>>>> Kind regards,
>>>> Alisa-Dariana Roman.
>>>
>>> Great, thanks!
>>
>> Just one quick question:
>>
>> I am getting two such warnings when running the checkpatch script:
>>
>> WARNING: else is not generally useful after a break or return
>> #1335: FILE: ./drivers/iio/adc/ad7192.c:1335:
>> +        return dev_err_probe(dev, ret, "Failed to get AVDD voltage\n");
>> +    } else {
>>
>> Should I switch the last two branches to get rid of the warnings or just ignore them?
>>
> 
> In the other patches, I was able to reorder things to avoid this
> warning, but since this one was more complicated, I just ignored
> this warning.
> 
> We can't just remove the else in this case because the return
> is inside of an `else if`.

	/* AVDD can optionally be used as reference voltage */
	ret = devm_regulator_get_enable_read_voltage(dev, "avdd");
	if (ret == -ENODEV || ret == -EINVAL) {
		/*
		 * We get -EINVAL if avdd is a supply with unknown voltage. We
		 * still need to enable it since it is also a power supply.
		 */
		ret = devm_regulator_get_enable(dev, "avdd");
		if (ret)
			return dev_err_probe(dev, ret,
					     "Failed to enable AVDD supply\n");

		avdd_mv = 0;
	} else if (ret >= 0) {
		avdd_mv = ret / MILLI;
	} else {
		return dev_err_probe(dev, ret, "Failed to get AVDD voltage\n");
	}

Would switching the last two branches, in order to get rid of the 
warnings, make the code harder to understand?