linux-kernel - Re: [PATCH v2 4/7] thermal: exynos: simplify regulator (de)initialization

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Date:   Fri, 29 Sep 2023 13:45:07 +0200
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Marek Szyprowski <m.szyprowski@...sung.com>,
        m.majewski2@...sung.com,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "linux-samsung-soc@...r.kernel.org" 
        <linux-samsung-soc@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Cc:     Bartlomiej Zolnierkiewicz <bzolnier@...il.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Amit Kucheria <amitk@...nel.org>,
        Zhang Rui <rui.zhang@...el.com>,
        ALIM AKHTAR <alim.akhtar@...sung.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>
Subject: Re: [PATCH v2 4/7] thermal: exynos: simplify regulator
 (de)initialization

On 29/09/2023 13:03, Marek Szyprowski wrote:
> On 29.09.2023 12:46, Daniel Lezcano wrote:
>> On 26/09/2023 13:02, Mateusz Majewski wrote:
>>> Hi,
>>>
>>>> This is not equivalent. If regulator is provided and enable fails, the
>>>> old code is nicely returning error. Now, it will print misleading
>>>> message - failed to get regulator - and continue.
>>>>
>>>> While this simplifies the code, it ignores important running
>>>> condition -
>>>> having regulator enabled.
>>>
>>> Would doing this be correct?
>>>
>>> ret = devm_regulator_get_enable_optional(&pdev->dev, "vtmu");
>>> switch (ret) {
>>> case 0:
>>> case -ENODEV:
>>
>> Not sure to understand why -NODEV is not an error
> 
> 
> Because this what devm_regulator_get_enable_optional() returns if no
> regulator is defined. I also got confused by this a few times.

The code before this change calls devm_regulator_get_optional() which 
returns -ENODEV too, right ? But there is no special case for this error.

So this change uses devm_regulator_get_enable_optional() and handle the 
ENODEV as a non-error, so there is a change in the behavior.


>>>      break;
>>> case -EPROBE_DEFER:
>>>      return -EPROBE_DEFER;
>>> default:
>>>      dev_err(&pdev->dev, "Failed to get enabled regulator: %d\n",
>>>          ret);
>>>      return ret;
>>> }
>>
>> ret = devm_regulator_get_enable_optional(&pdev->dev, "vtmu");
>> if (ret < 0) {
>>      if (ret != EPROBE_DEFER)
>>          dev_err(&pdev->dev, "Failed to get enabled regulator: %d\n",
>> ret);
>>      return ret;
>> }
>>
>> ??
>>
> Best regards

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