linux-kernel - Re: [PATCH v1 2/5] dt-binding: rtc-pcf85063: add quartz load property

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Date:   Thu, 13 Sep 2018 21:11:50 +0200
From:   Alexandre Belloni <alexandre.belloni@...tlin.com>
To:     Sam Ravnborg <sam@...nborg.org>
Cc:     Alessandro Zummo <a.zummo@...ertech.it>,
        Andrew Jeffery <andrew@...id.au>,
        Fabio Estevam <fabio.estevam@....com>,
        Joel Stanley <joel@....id.au>,
        Mark Rutland <mark.rutland@....com>,
        Rob Herring <robh+dt@...nel.org>,
        Russell King <linux@...linux.org.uk>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Shawn Guo <shawnguo@...nel.org>, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-rtc@...r.kernel.org,
        Søren Andersen <san@...v.dk>
Subject: Re: [PATCH v1 2/5] dt-binding: rtc-pcf85063: add quartz load property

Hi,

You can remove 'rtc-' from the part name in the subject.

On 07/09/2018 21:35:05+0200, Sam Ravnborg wrote:
> From: Søren Andersen <san@...v.dk>
> 
> The NXP pcf85063 support two different quartz loads.
> - 7 pF (default)
> - 12.5 pF (minimum power consumption)
> 
> The pcf85063 needs to know the size of the external capacitor,
> otherwise the RTC will have a bad precision (hours/week).
> 
> The power-on default is 7 pF
> Add a property that tells if the external capacitor is 12.5 pF
> 
> Signed-off-by: Søren Andersen <san@...v.dk>
> Signed-off-by: Sam Ravnborg <sam@...nborg.org>
> Cc: Alessandro Zummo <a.zummo@...ertech.it>
> Cc: Alexandre Belloni <alexandre.belloni@...tlin.com>
> Cc: Rob Herring <robh+dt@...nel.org>
> Cc: Mark Rutland <mark.rutland@....com>
> ---
>  .../devicetree/bindings/rtc/nxp,pcf85063.txt          | 19 +++++++++++++++++++
>  Documentation/devicetree/bindings/trivial-devices.txt |  1 -
>  2 files changed, 19 insertions(+), 1 deletion(-)
>  create mode 100644 Documentation/devicetree/bindings/rtc/nxp,pcf85063.txt
> 
> diff --git a/Documentation/devicetree/bindings/rtc/nxp,pcf85063.txt b/Documentation/devicetree/bindings/rtc/nxp,pcf85063.txt
> new file mode 100644
> index 000000000000..22ebb2ce52c1
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/rtc/nxp,pcf85063.txt
> @@ -0,0 +1,19 @@
> +* NXP PCF85063 Real Time Clock
> +
> +NXP PCF85063 Real Time Clock
> +
> +Required properties:
> +- compatible: Should contain "nxp,pcf85063".
> +- reg: I2C address for chip.
> +
> +Optional property:
> +- nxp,quartz_load_12.5pF: The capacitive load on the quartz is 12.5 pF,
> +  which differ from the default value of 7 pF
> +
> +Example:
> +
> +pcf85063: pcf85063@51 {
> +	compatible = "nxp,pcf85063";
> +	reg = <0x51>;
> +	nxp,quartz_load_12.5pF;

Same comment as the previous patch, a value in fF is more useful. It
could also probably be made a generic rtc property.


-- 
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com