linux-kernel - [PATCH 0/2] pcf85363: support for quartz-load-femtofarads

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Message-ID: <20230213095018.2255225-1-javier.carrasco@wolfvision.net>
Date:   Mon, 13 Feb 2023 10:50:16 +0100
From:   Javier Carrasco <javier.carrasco@...fvision.net>
To:     linux-rtc@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
CC:     Alessandro Zummo <a.zummo@...ertech.it>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Michael Riesch <michael.riesch@...fvision.net>,
        Javier Carrasco <javier.carrasco@...fvision.net>
Subject: [PATCH 0/2] pcf85363: support for quartz-load-femtofarads

These patches add support for the quartz-load-femtofarads property in
the pcf85363 device driver and a description of the property's possible
values. 

The driver has been tested with a PCF85263ATT RTC and a CTS3-32.768-12.5-20
oscillator that needs a 12.5 pF load capacitor. With no property
support the 7 pF default value leads to at least 2 Hz output frequency
deviations, while setting the right value the deviation decreased to
0.15 Hz. These measurements were made with a high precision oscilloscope
(SIGLENT SDS5104X).

This modification does not affect existing designs where the
quartz-load-femtofarads is not defined because in that case the default
value is used.

Javier Carrasco (2):
  rtc: pcf85363: add support for the quartz-load-femtofarads property
  dt-bindings: rtc: nxp,pcf8563: add quartz-load-femtofarads for
    pcf85263 and pcf85363

 .../devicetree/bindings/rtc/nxp,pcf8563.yaml  | 20 ++++++++--
 drivers/rtc/rtc-pcf85363.c                    | 37 ++++++++++++++++++-
 2 files changed, 53 insertions(+), 4 deletions(-)

-- 
2.37.2

Javier Carrasco 
Research and Development

Wolfvision GmbH 
Oberes Ried 14 | 6833 Klaus | Austria 
Tel: +43 5523 52250 <tel:+43552352250> | Mail: javier.carrasco@...fvision.net <mailto:javier.carrasco@...fvision.net>

Website: wolfvision.com <www.wolfvision.com> 
Firmenbuch / Commercial Register: FN283521v Feldkirch/Austria