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

[Adriana Reus]

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@xxxxxxxxxx> 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@xxxxxxxxx>
> > 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.

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).
> > > +- upisemi,glass-coef: glass attenuation factor
> > > +- upisemi,dark-ths: array of thresholds (adc counts) corresponding to every scale
>
> What is the size of the array and valid range of values?
>
> Be specific this is 16-bit property.
Ok, I'll add this info in a following patch set.
> > > +- upisemi,upper-dark-gain: tuning factor(4 int and 4 fractional bits - Q4.4) applied when light > threshold
> > > +- upisemi,lower-dark-gain: tuning factor(4 int and 4 fractional bits - Q4.4) applied when light < threshold
>
> Be specific this is an 8-bit property.
ok
> > > +
> > > +Example:
> > > +
> > > +    usd5182@39 {
> > > +                compatible = "upisemi,usd5182";
> > > +                reg = <0x39>;
> > > +                upisemi,glass-coef = < 1000 >;
> > > +                upisemi,dark-ths = /bits/ 16 <170 200 512 512 800 2000 4000 8000>;
> > > +                upisemi,upper-dark-gain = /bits/ 8 <0x00>;
> > > +                upisemi,lower-dark-gain = /bits/ 8 <0x16>;
> > > +    };
> > > +
> > > diff --git a/Documentation/devicetree/bindings/vendor-prefixes.txt b/Documentation/devicetree/bindings/vendor-prefixes.txt
> > > index d444757..5b40bab 100644
> > > --- a/Documentation/devicetree/bindings/vendor-prefixes.txt
> > > +++ b/Documentation/devicetree/bindings/vendor-prefixes.txt
> > > @@ -211,6 +211,7 @@ toshiba   Toshiba Corporation
> > >   toumaz       Toumaz
> > >   tplink       TP-LINK Technologies Co., Ltd.
> > >   truly        Truly Semiconductors Limited
> > > +upisemi      uPI Semiconductor Corp.
> > >   usi  Universal Scientific Industrial Co., Ltd.
> > >   v3   V3 Semiconductor
> > >   variscite    Variscite Ltd.
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