Re: [PATCH 3/4] rtc: ds1307: add calibration of_ for mt41txx chips.

From: Rob Herring
Date: Tue May 08 2018 - 13:40:53 EST


On Tue, May 8, 2018 at 9:56 AM, Giulio Benetti
<giulio.benetti@xxxxxxxxxxxxxxxx> wrote:
> m41txx chips can hold a calibration value to get really near to real
> tick value.

Typo in the subject.

> Add calibration property(ranging between (-31) and 31), so on every probe
> calibration value will be written to rtc.
> This is because ic could loose supply due to low battery.
>
> Signed-off-by: Giulio Benetti <giulio.benetti@xxxxxxxxxxxxxxxx>
> ---
> .../devicetree/bindings/rtc/rtc-ds1307.txt | 2 ++

Put all the binding changes in separate patch (or maybe 2: new
compatible and new properties).

> drivers/rtc/rtc-ds1307.c | 33 +++++++++++++++++++
> 2 files changed, 35 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/rtc/rtc-ds1307.txt b/Documentation/devicetree/bindings/rtc/rtc-ds1307.txt
> index ce6469c1a516..d3d70a5495c5 100644
> --- a/Documentation/devicetree/bindings/rtc/rtc-ds1307.txt
> +++ b/Documentation/devicetree/bindings/rtc/rtc-ds1307.txt
> @@ -34,6 +34,8 @@ Optional properties:
> - trickle-diode-disable : ds1339, ds1340 and ds 1388 only
> Do not use internal trickle charger diode
> Should be given if internal trickle charger diode should be disabled
> +- calibration: m41t0, m41t00, m41t11 only

Needs a vendor prefix.

Calibration of what and what are the units?

> + Set calibration value to correct external bias, ranging between (-31) and 31.
>
> Example:
> rtc1: ds1339@68 {