[v2] pcf85363: support for quartz-load-femtofarads

[PATCH v2 0/2] pcf85363: support for quartz-load-femtofarads

Posted by Javier Carrasco 2 years, 6 months ago

These patches add support for the quartz-load-femtofarads property in
the pcf85363 device driver and new bindings for the pcf85263 and
pcf85363 Real Time Clocks.

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):
  dt-bindings: rtc: nxp,pcf8563: move pcf85263/pcf85363 to a dedicated
    binding
  rtc: pcf85363: add support for the quartz-load-femtofarads property

 .../devicetree/bindings/rtc/nxp,pcf85363.yaml | 60 +++++++++++++++++++
 .../devicetree/bindings/rtc/nxp,pcf8563.yaml  |  2 -
 drivers/rtc/rtc-pcf85363.c                    | 37 +++++++++++-
 3 files changed, 96 insertions(+), 3 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/rtc/nxp,pcf85363.yaml

-- 
2.37.2

Re: [PATCH v2 0/2] pcf85363: support for quartz-load-femtofarads

Posted by Alexandre Belloni 2 years, 6 months ago

On Wed, 15 Feb 2023 09:18:13 +0100, Javier Carrasco wrote:
> These patches add support for the quartz-load-femtofarads property in
> the pcf85363 device driver and new bindings for the pcf85263 and
> pcf85363 Real Time Clocks.
> 
> 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).
> 
> [...]

Applied, thanks!

[1/2] dt-bindings: rtc: nxp,pcf8563: move pcf85263/pcf85363 to a dedicated binding
      commit: 1b2f85a8bac67b9909f2ee4be1bc11548a7aeaf3
[2/2] rtc: pcf85363: add support for the quartz-load-femtofarads property
      commit: fd9a6a13949af81062f4cd04f2c1b28ca5311e71

Best regards,

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