Date:	Tue, 18 Aug 2015 18:36:23 +0100
From:	Jonathan Cameron <jic23@...23.retrosnub.co.uk>
To:	Adriana Reus <adriana.reus@...el.com>,
	Jonathan Cameron <jic23@...nel.org>, pmeerw@...erw.net,
	daniel.baluta@...el.com
CC:	linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
	devicetree@...r.kernel.org
Subject: Re: [PATCH v3 2/2] devicetree: Add documentation for UPISEMI us5182d ALS and Proximity sensor



On 18 August 2015 16:13:02 BST, Adriana Reus <adriana.reus@...el.com> wrote:
>
>Thank you Jonathan, I'll add a new patch set soon, added some comments 
>inline also.
>
>Adriana
>On 15.08.2015 17:31, Jonathan Cameron wrote:
>> On 14/08/15 10:29, Adriana Reus wrote:
>>> Added entries in trivial-devices and 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>
>> It's not a trivial device if it has it's own docs.  So don't add it
>to that list
>> (the point is to not have separate docs for devices that don't really
>have
>> any device tree data other than where they are.
>right, I'll add a new path set soon.
>>
>> Few more bits inline.
>>> ---
>>>    No changes - resending because I forgot to cc devicetree.
>>>   .../devicetree/bindings/i2c/trivial-devices.txt    |  1 +
>>>   .../devicetree/bindings/iio/light/us5182d.txt      | 24
>++++++++++++++++++++++
>>>   .../devicetree/bindings/vendor-prefixes.txt        |  1 +
>>>   3 files changed, 26 insertions(+)
>>>   create mode 100644
>Documentation/devicetree/bindings/iio/light/us5182d.txt
>>>
>>> diff --git
>a/Documentation/devicetree/bindings/i2c/trivial-devices.txt
>b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
>>> index 00f8652..96d3b9c 100644
>>> --- a/Documentation/devicetree/bindings/i2c/trivial-devices.txt
>>> +++ b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
>>> @@ -99,4 +99,5 @@ ti,tsc2003		I2C Touch-Screen Controller
>>>   ti,tmp102		Low Power Digital Temperature Sensor with SMBUS/Two
>Wire Serial Interface
>>>   ti,tmp103		Low Power Digital Temperature Sensor with SMBUS/Two
>Wire Serial Interface
>>>   ti,tmp275		Digital Temperature Sensor
>>> +upisemi,usd5182		Als and Proximity Sensor
>>>   winbond,wpct301		i2c trusted platform module (TPM)
>>> diff --git a/Documentation/devicetree/bindings/iio/light/us5182d.txt
>b/Documentation/devicetree/bindings/iio/light/us5182d.txt
>>> new file mode 100644
>>> index 0000000..9ac3336
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/iio/light/us5182d.txt
>>> @@ -0,0 +1,24 @@
>>> +* UPISEMI us5182d I2C ALS and Proximity sensor
>>> +
>>> +Required properties:
>>> +- compatible: must be "upisemi,usd5182"
>>> +- reg: the I2C address of the device
>>> +
>>> +Optional properties:
>>> +- upisemi,glass-coef: glass attenuation factor
>>> +- upisemi,dark-ths: array of thresholds corresponding to every
>scale
>> That needs more detail. I've read the driver and I am not sure what
>exactly
>> you mean!  Why should a scale have a threshold?
>I'll try to be more specific. These are values representing adc counts,
>
>that's why there are different values corresponding to every scale.
>>> +- upisemi,upper-dark-gain: tuning factor applied when light > th
>>> +- upisemi,lower-dark-gain: tuning factor applied when light < th
>>> +
>>> +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>;
>> Not sure why these are in hex.. Or why we care if they are 8 bits. 
>If there is a limit
>> on the possible values, perhaps mention it in the docs above.
>I should have been (much) more specific here: that represents a float 
>number with 4 integer bits and 4 fractional bits (Q4.4), so I find hex 
>more intuitive since it's split in half, let me know if you think 
>otherwise. 
One for the device tree guys to answer rather than me.  My gut feeling would be
a representation that made this obvious but I have no idea what normal choice would be.
>I'll add a more complete description. As for the "/bits/ x" 
>it's because currently in the driver I use the read_property_u8 or
>*_u16 
>functions, these require that the dts entry be as I wrote it in the 
>example, and since it's an example it should be functional, so I feel 
>that is ok as it is.
>>
>>
>>> +    };
>>> +
>> One blank line at the end is neough.
>>> +
>>> 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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