linux-kernel - Re: [PATCH] Device tree binding for Avago APDS990X light sensor

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Date:   Wed, 27 Dec 2017 19:50:42 +0100
From:   Filip Matijević <filip.matijevic.pz@...il.com>
To:     Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Pavel Machek <pavel@....cz>
Cc:     robh+dt@...nel.org, mark.rutland@....com,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        pali.rohar@...il.com, sre@...nel.org,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        linux-omap@...r.kernel.org, tony@...mide.com, khilman@...nel.org,
        aaro.koskinen@....fi, ivo.g.dimitrov.75@...il.com,
        patrikbachan@...il.com, serge@...lyn.com, abcloriens@...il.com,
        clayton@...ftyguy.net, martijn@...xit.nl
Subject: Re: [PATCH] Device tree binding for Avago APDS990X light sensor

Hi Sakari,

and thank you for your input - I've added a few comments below.

On 12/27/2017 07:00 PM, Sakari Ailus wrote:
> Hi Pavel,
> 
> Thanks for the patch. Please see my comments below.
> 
> On Wed, Dec 27, 2017 at 10:18:28AM +0100, Pavel Machek wrote:
>> From: Filip Matijević <filip.matijevic.pz@...il.com>
>>
>> This prepares binding for light sensor used in Nokia N9. 
>>
>> Signed-off-by: Filip Matijević <filip.matijevic.pz@...il.com>
>> Signed-off-by: Pavel machek <pavel@....cz>
>>
>> ---
>>
>> Patches to convert APDS990X driver to device tree and to switch to iio
>> are available.
>>
>> diff --git a/Documentation/devicetree/bindings/misc/avago-apds990x.txt b/Documentation/devicetree/bindings/misc/avago-apds990x.txt
>> new file mode 100644
>> index 0000000..e038146
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/misc/avago-apds990x.txt
>> @@ -0,0 +1,39 @@
>> +Avago APDS990X driver
>> +
>> +Required properties:
>> +- compatible: "avago,apds990x"
>> +- reg: address on the I2C bus
>> +- interrupts: external interrupt line number
>> +- Vdd-supply: power supply for VDD
>> +- Vled-supply: power supply for LEDA
> 
> AFAIK the custom is to use lower case letters for regulator supplies.

I've just used the same notation as in current driver. Datasheet calls
those VDD (with DD being in subscript) and LEDA. I see no problem in
changing those to vdd-supply and vled-supply if no one else objects.

> 
>> +- ga: Glass attenuation
>> +- cf1: Clear channel factor 1
>> +- irf1: IR channel factor 1
>> +- cf2: Clear channel factor 2
>> +- irf2: IR channel factor 2
>> +- df: Device factor
>> +- pdrive: IR current, one of APDS_IRLED_CURR_XXXmA values
>> +- ppcount: Proximity pulse count
> 
> Are these device specific? If so, please add the vendor prefix to them.

AFAIK yes - same as before if no one else objects, these will be changed.

> 
> I might not use short abbreviations such as "df" either. I wonder what
> others think.

These are also come from current driver - some of these comes from the
datasheet itself, but not all. For example "ga" and "df" are in there
(so I I would leave those alone), but "irf1" is called "B", "cf2" is
called "C" and "irf2" is called "D" (I guess the missing "cf1" should be
"A", but there is no such thing in the datasheet).
IMHO using some other names might just add to the confusion.

> 
>> +
>> +Example (Nokia N9):
>> +
>> +	als_ps@39 {
>> +		compatible = "avago,apds990x";
>> +		reg = <0x39>;
>> +
>> +		interrupt-parent = <&gpio3>;
>> +		interrupts = <19 10>; /* gpio_83, IRQF_TRIGGER_FALLING | IRQF_TRIGGER_LOW */
>> +
>> +		Vdd-supply = <&vaux1>;
>> +		Vled-supply = <&vbat>;
>> +
>> +		ga	= <168834>;
>> +		cf1	= <4096>;
>> +		irf1	= <7824>;
>> +		cf2	= <877>;
>> +		irf2	= <1575>;
>> +		df	= <52>;
>> +
>> +		pdrive	= <0x2>; /* APDS_IRLED_CURR_25mA */
>> +		ppcount	= <5>;
>> +	};
>>
> 

Best regards,
Filip