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Subject: Re: [PATCH v2 3/4] iio: vcnl4000: Export near level property for
 proximity sensor
To:     =?UTF-8?Q?Guido_G=c3=bcnther?= <agx@sigxcpu.org>
Cc:     Tomas Novotny <tomas@novotny.cz>,
        Jonathan Cameron <jic23@kernel.org>,
        Hartmut Knaack <knaack.h@gmx.de>,
        Peter Meerwald-Stadler <pmeerw@pmeerw.net>,
        "Angus Ainslie (Purism)" <angus@akkea.ca>,
        Marco Felsch <m.felsch@pengutronix.de>,
        Thomas Gleixner <tglx@linutronix.de>,
        linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org,
        devicetree@vger.kernel.org
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 <20200317120535.GA16807@bogon.m.sigxcpu.org>
From:   Lars-Peter Clausen <lars@metafoo.de>
Message-ID: <ab8f970b-f95f-b34b-7e4d-c2cc64d94886@metafoo.de>
Date:   Tue, 17 Mar 2020 14:11:36 +0100
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On 3/17/20 1:05 PM, Guido Günther wrote:
> Hi,
> On Mon, Mar 16, 2020 at 07:23:01PM +0100, Lars-Peter Clausen wrote:
>> On 3/16/20 6:46 PM, Guido Günther wrote:
>>> [...]
>>> +static ssize_t vcnl4000_read_near_level(struct iio_dev *indio_dev,
>>> +					uintptr_t priv,
>>> +					const struct iio_chan_spec *chan,
>>> +					char *buf)
>>> +{
>>> +	struct vcnl4000_data *data = iio_priv(indio_dev);
>>> +
>>> +	return sprintf(buf, "%u\n", data->near_level);
>>> +}
>>> +
>>> +static const struct iio_chan_spec_ext_info vcnl4000_ext_info[] = {
>>> +	{
>>> +		.name = "near_level",
>> Generally having properties with a underscore in them breaks generic parsing
>> of the property name by userspace applications. This is because we use
>> underscores to separate different components (type, modifier, etc.) of the
>> attribute from each other.
>>
>> Do you think calling this "nearlevel" would work?
> That works as well. I'll change that for v3.
>
> For my education: Is the type, modifier policy written down somewhere
> (similar to
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/leds/leds-class.rst#n44
> )?

Good point, this is quite badly documented at the moment.

The only thing I could find is this presentation by Daniel 
https://events.static.linuxfound.org/sites/events/files/slides/lceu15_baluta.pdf#page=9

- Lars