linux-kernel - Re: [PATCH v6 2/2] devicetree: Add documentation for UPISEMI us5182d ALS and Proximity sensor

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Date:	Tue, 8 Sep 2015 20:05:41 -0500
From:	Rob Herring <robherring2@...il.com>
To:	Adriana Reus <adriana.reus@...el.com>,
	Jonathan Cameron <jic23@...nel.org>
Cc:	Peter Meerwald <pmeerw@...erw.net>, daniel.baluta@...el.com,
	"linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>
Subject: Re: [PATCH v6 2/2] devicetree: Add documentation for UPISEMI us5182d
 ALS and Proximity sensor

On 09/07/2015 08:59 AM, Adriana Reus wrote:
> Thanks for your feedback, some comments inline.
> 
> On 31.08.2015 18:38, Rob Herring wrote:
>> On Thu, Aug 27, 2015 at 3:23 PM, Jonathan Cameron <jic23@...nel.org>
>> wrote:
>>> On 20/08/15 11:12, Adriana Reus wrote:
>>>> Added entries in i2c/vendor-prefixes for the us5182d als and
>>>> proximity sensor.
>>>> Also added a documentation file for this sensor's properties.
>>>>
>>>> Signed-off-by: Adriana Reus <adriana.reus@...el.com>
>>> This isn't that trivial so I'd like some device tree maintainer
>>> input if possible.
>>
>> It seems fairly reasonable to me. Would other ALS or proximity sensors
>> need similar properties?
> The "glass-coef" is intended to compensate for the material (glass) that
> may be covering the sensor if it's integrated in a phone, tablet etc. I
> chose 1000 as resolution for this scaling factor (i'll add a more
> detailed description). So possibly similar properties could be used for
> other als sensors as well.

Seems like amstaos,cover-comp-gain would be doing the same thing. But it
is defined as an integer, so I'm not sure how that would work.

> 
> The last 3 tuning parameters are specific to this particular sensor.
>>
>>> For now I've backed out the driver from my tree (given timing we have
>>> loads of time to sort this out!)
>>>
>>> Anyhow, anyone device tree related able to take a look at this.
>>>
>>> Adriana, btw these should be cc'd to the device tree maintainers in
>>> the first place (now added).
>>>
>>> Jonathan
>>>> ---
>>>>   .../devicetree/bindings/iio/light/us5182d.txt      | 23
>>>> ++++++++++++++++++++++
>>>>   .../devicetree/bindings/vendor-prefixes.txt        |  1 +
>>>>   2 files changed, 24 insertions(+)
>>>>   create mode 100644
>>>> Documentation/devicetree/bindings/iio/light/us5182d.txt
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/iio/light/us5182d.txt
>>>> b/Documentation/devicetree/bindings/iio/light/us5182d.txt
>>>> new file mode 100644
>>>> index 0000000..7785c56
>>>> --- /dev/null
>>>> +++ b/Documentation/devicetree/bindings/iio/light/us5182d.txt
>>>> @@ -0,0 +1,23 @@
>>>> +* UPISEMI us5182d I2C ALS and Proximity sensor
>>>> +
>>>> +Required properties:
>>>> +- compatible: must be "upisemi,usd5182"
>>>> +- reg: the I2C address of the device
>>>> +
>>>> +Optional properties:
>>
>> Do you expect certain defaults if not present? Some description of how
>> all these values are determined would be useful.
> Yes, if not present they will fall back to default values - the values
> in the example.
> - the glass-coef one is 1000 by default - so no glass compensation by
> default (lux = lux * 1000/1000)
> - the others were determined experimentally - by fine tuning starting
> from the default values in those registers).

So the default if the properties are not present is a default register
value or a default in the driver?

Rob
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