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

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Hi Rob,

Il 08/05/2018 19:40, Rob Herring ha scritto:
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 {

This is not a problem anymore since I've used standard rtc sysfs "offset" instead of a dt-property as Alexandre pointed me out.

Thanks.

--
Giulio Benetti
CTO

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