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From: Rob Herring <robh@kernel.org>
Date: Sun, 20 Sep 2015 20:51:32 -0500
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Subject: Re: Please suggest proper format for DT properties.
To: Constantine Shulyupin <const@makelinux.com>
Cc: open list <linux-kernel@vger.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
	<devicetree@vger.kernel.org>,
        lm-sensors@lm-sensors.org, Jean Delvare <jdelvare@suse.com>,
        Guenter Roeck <linux@roeck-us.net>, Rob Herring <robh+dt@kernel.org>,
        Pawel Moll <pawel.moll@arm.com>, Mark Rutland <mark.rutland@arm.com>,
        Ian Campbell <ijc+devicetree@hellion.org.uk>,
        Kumar Gala <galak@codeaurora.org>
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On Fri, Sep 18, 2015 at 5:36 PM, Constantine Shulyupin
<const@makelinux.com> wrote:
> Hi,
>
> I am designing DT support for a hwmon chip.
> It has some sensors, each of them can be:
>  - "disabled"
>  - "thermal diode"
>  - "thermistor"
>  - "voltage"
>
> Four possible options for DT properties format.
>
> Option 1: Separated property for each sensor.
>
> Example nct7802 node:
>
> nct7802 {
>         compatible = "nuvoton,nct7802";
>         reg = <0x2a>;
>         nuvoton,sensor1-type = "thermistor";
>         nuvoton,sensor2-type = "disabled";
>         nuvoton,sensor3-type = "voltage";
> };
>
> Option 2: Array of strings for all sensors.
>
> nct7802 {
>         compatible = "nuvoton,nct7802";
>         reg = <0x2a>;
>         nuvoton,sensors-types = "thermistor", "disabled", "voltage";
> };

It seems you are just listing out all possible modes. Why do you need
this in the DT at all? This can be inferred by the compatible string.

>
> Option 3: Sets of 4 cells.
>
>   Borrowed from marvell,reg-init and broadcom,c45-reg-init.
>
>   The first cell is the page address,
>   the second a register address within the page,
>   the third cell contains a mask to be ANDed with the existing register
>   value, and the fourth cell is ORed with the result to yield the
>   new register value. If the third cell has a value of zero,
>   no read of the existing value is performed.

I don't see how this relates to the first 2 options. The register you
write selects the mode? In general, we don't want bindings of just
random register writes.

Rob