From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexandre Belloni Subject: Re: [PATCH v1 1/5] dt-binding: rtci-pcf8523: add quartz_load property Date: Wed, 26 Sep 2018 20:51:21 +0200 Message-ID: <20180926185121.GF16644@piout.net> References: <20180822183555.GA24084@ravnborg.org> <20180907193508.24974-2-sam@ravnborg.org> <20180913190516.GG14988@piout.net> <20180926154708.GA3264@bogus> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20180926154708.GA3264@bogus> Sender: linux-kernel-owner@vger.kernel.org To: Rob Herring Cc: Sam Ravnborg , Alessandro Zummo , Andrew Jeffery , Fabio Estevam , Joel Stanley , Mark Rutland , Russell King , Sascha Hauer , Shawn Guo , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-rtc@vger.kernel.org, =?iso-8859-1?Q?S=F8ren?= Andersen List-Id: devicetree@vger.kernel.org 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 > here? > 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 https://bootlin.com