Message-ID: <b635b91e-1dcc-71ba-95d1-1f87a20dbaf2@metafoo.de>
Date:   Thu, 2 Mar 2023 05:20:38 -0800
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Subject: Re: [PATCH v3 2/2] iio: adc: Add TI ADS1100 and ADS1000
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From:   Lars-Peter Clausen <lars@metafoo.de>
To:     Mike Looijmans <mike.looijmans@topic.nl>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc:     devicetree@vger.kernel.org, linux-iio@vger.kernel.org,
        Caleb Connolly <caleb.connolly@linaro.org>,
        ChiYuan Huang <cy_huang@richtek.com>,
        ChiaEn Wu <chiaen_wu@richtek.com>,
        Cosmin Tanislav <demonsingur@gmail.com>,
        Ibrahim Tilki <Ibrahim.Tilki@analog.com>,
        Jonathan Cameron <jic23@kernel.org>,
        Ramona Bolboaca <ramona.bolboaca@analog.com>,
        William Breathitt Gray <william.gray@linaro.org>,
        linux-kernel@vger.kernel.org
References: <20230228063151.17598-1-mike.looijmans@topic.nl>
 <20230228063151.17598-2-mike.looijmans@topic.nl>
 <Y/9vez/fzLD5dRVF@smile.fi.intel.com>
 <1b153bce-a66a-45ee-a5c6-963ea6fb1c82.949ef384-8293-46b8-903f-40a477c056ae.0685d97e-4a28-499e-a9e3-3bafec126832@emailsignatures365.codetwo.com>
 <a2ba706f-888b-0a72-03a5-cbf761dfaf19@topic.nl>
 <87bc192e-45ae-9480-5e84-8fe0adfc12e7@metafoo.de>
In-Reply-To: <87bc192e-45ae-9480-5e84-8fe0adfc12e7@metafoo.de>
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On 3/2/23 05:16, Lars-Peter Clausen wrote:
> On 3/1/23 23:49, Mike Looijmans wrote:
>>
>>
>>> ...
>>> ...
>>>
>>>> +static int ads1100_runtime_suspend(struct device *dev)
>>>> +{
>>>> +    struct iio_dev *indio_dev = 
>>>> i2c_get_clientdata(to_i2c_client(dev));
>>>> +    struct ads1100_data *data = iio_priv(indio_dev);
>>>> +
>>>> +    ads1100_set_config_bits(data, ADS1100_CFG_SC, 
>>>> ADS1100_SINGLESHOT);
>>>> +    regulator_disable(data->reg_vdd);
>>> Wrong devm / non-devm ordering.
>>
>> Don't understand your remark, can you explain further please?
>>
>> devm / non-devm ordering would be related to the "probe" function. As 
>> far as I can tell, I'm not allocating resources after the devm calls. 
>> And the "remove" is empty.
>
> Strictly speaking we need to unregister the IIO device before 
> disabling the regulator, otherwise there is a small window where the 
> IIO device still exists, but doesn't work anymore. This is a very 
> theoretical scenario though.
>
> You are lucky :) There is a new function 
> `devm_regulator_get_enable()`[1], which will manage the 
> regulator_disable() for you. Using that will also reduce the 
> boilerplate in `probe()` a bit
>
> - Lars
>
> [1] https://lwn.net/Articles/904383/
>
Sorry, just saw that Andy's comment was on the suspend() function, not 
remove(). In that case there is of course no need for any devm things. 
But still a good idea to use `devm_regulator_get_enable()` in probe for 
the boiler plate.