linux-kernel - Re: [PATCH 2/5] Documentation: devicetree: Add property for controlling power saving mode for the us5182 als sensor

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Message-ID: <20151125000130.GA21418@rob-hp-laptop>
Date:	Tue, 24 Nov 2015 18:01:30 -0600
From:	Rob Herring <robh@...nel.org>
To:	Adriana Reus <adriana.reus@...el.com>
Cc:	jic23@...nel.org, linux-iio@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-pm@...r.kernel.org, ijc+devicetree@...lion.org.uk,
	galak@...eaurora.org, pawel.moll@....com, pmeerw@...erw.net,
	lars@...afoo.de
Subject: Re: [PATCH 2/5] Documentation: devicetree: Add property for
 controlling power saving mode for the us5182 als sensor

On Tue, Nov 24, 2015 at 12:59:49PM +0200, Adriana Reus wrote:
> Add a property to allow changing the default power-saving mode.
> By default, at read raw the chip will activate and provide
> one measurent, then it will shut itself down. However, the
> chip can also work in "continuous" mode which may be more reliable
> but is also more power consuming.
> 
> Signed-off-by: Adriana Reus <adriana.reus@...el.com>
> ---
>  Documentation/devicetree/bindings/iio/light/us5182d.txt | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/iio/light/us5182d.txt b/Documentation/devicetree/bindings/iio/light/us5182d.txt
> index 6f0a530..a619799 100644
> --- a/Documentation/devicetree/bindings/iio/light/us5182d.txt
> +++ b/Documentation/devicetree/bindings/iio/light/us5182d.txt
> @@ -7,13 +7,24 @@ Required properties:
>  Optional properties:
>  - upisemi,glass-coef: glass attenuation factor - compensation factor of
>                        resolution 1000 for material transmittance.
> +
>  - upisemi,dark-ths: array of 8 elements containing 16-bit thresholds (adc
>                      counts) corresponding to every scale.
> +
>  - upisemi,upper-dark-gain: 8-bit dark gain compensation factor(4 int and 4
>                             fractional bits - Q4.4) applied when light > threshold
> +
>  - upisemi,lower-dark-gain: 8-bit dark gain compensation factor(4 int and 4
>                             fractional bits - Q4.4) applied when light < threshold
>  
> +- upisemi,continuous: This chip has two power modes: one-shot (chip takes one
> +                      measurement and then shuts itself down) and continuous (
> +                      chip takes continuous measurements). The one-shot mode is
> +                      more power-friendly but the continuous mode may be more
> +                      reliable. If this property is specified the continuous
> +                      mode will be used instead of the default one-shot one for
> +                      raw reads.

I could imagine an OS may want to decide this on its own or use a 
mixture of the modes.

Rob
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