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

From: Giulio Benetti
Date: Wed May 09 2018 - 14:34:05 EST

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.

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.


Giulio Benetti

Sede: Via A. Niedda 3 - 35010 Vigonza (PD)
Tel. 049/8931563 - Fax 049/8931346
Cod.Fiscale - P.IVA 02663420285
Capitale Sociale â 26.000 i.v.
Iscritta al Reg. Imprese di Padova N. 02663420285
Numero R.E.A. 258642