Re: [PATCH v1 1/5] dt-binding: rtci-pcf8523: add quartz_load property
From: Alexandre Belloni
Date: Wed Sep 26 2018 - 14:51:36 EST
On 26/09/2018 10:47:08-0500, Rob Herring wrote:
> > > +Optional property:
> > > +- nxp,quartz_load_12.5pF: The capacitive load on the quartz is 12.5 pF,
> > > + which differ from the default value of 7 pF
> > > +
> > The boolean properties usually don't work well for RTCs because people
> > usually want to keep any previous configuration that may have been done
> > at the factory or in the bootloader so I would use:
> > nxp,quartz_load_fF and this would be either 7000 or 12500.
> Use '-' rather than '_'.
> There's already a defined unit suffix of '-picofarads'. If you need
> '-femtofarads', then please add to property-units.txt. Though I'd prefer
> not as wouldn't a value of 12 (or 13) be close enough for the needs
For that particular RTC, yes but the isl1208 has 0.5pF steps and the
x1205 has 0.25pf steps. I'd prefer having a single generic property for
all the RTCs: quartz-load-femtofarads.
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering