From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Machek Subject: Re: [PATCH v4 3/6] Documentation: DT: Document twl4030-madc-battery bindings Date: Tue, 31 Mar 2015 09:26:43 +0200 Message-ID: <20150331072643.GB30788@amd> References: <1426022847-30912-1-git-send-email-marek@goldelico.com> <1426022847-30912-4-git-send-email-marek@goldelico.com> <20150311152414.GX5264@atomide.com> <844740CD-C95B-4411-A2C8-4906F58DBEE8@goldelico.com> <20150311164442.GA5264@atomide.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Content-Disposition: inline In-Reply-To: <20150311164442.GA5264-4v6yS6AI5VpBDgjK7y7TUQ@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Tony Lindgren Cc: "Dr. H. Nikolaus Schaller" , Marek Belisko , Benoit Cousson , Sebastian Reichel , Dmitry Eremin-Solenikov , David Woodhouse , Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, LKML , linux-omap-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel , linux-pm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: devicetree@vger.kernel.org Hi! > > >> + io-channels =3D <&twl_madc 1>, > > >> + <&twl_madc 10>, > > >> + <&twl_madc 12>; > > >> + io-channel-names =3D "temp", > > >> + "ichg", > > >> + "vbat"; > > >> + }; > > >=20 > > > Rather than just making platform_data into device tree properties= =2E. > > >=20 > > > Can't you hide the these custom properties behind the compatible = flag? > > >=20 > > > You can initialize that data in the driver based on the compatibl= e > > > flag and the match data. > > >=20 > > > This makes sense if you can group things to similar configuration= s. > >=20 > > Maybe I have not completely understood your proposal. > >=20 > > Do you mean to go back to have big parameter tables for each device= /battery > > combination in the driver code and the compatible flag (e.g. compat= ible =3D =E2=80=9Cboard17=E2=80=9D) > > chooses the right data set for the charging map and channels? >=20 > If you can somehow group them, then yes. Not for every board if there > are many of them naturally. > =20 > > I thought this is what the DT was introduced for - to have the same= driver=20 > > code but adapt to different boards depending on hardware variations= =2E >=20 > Yeah but you also need to consider the issues related to introducing > new device tree properties. The device tree properties introduced > should be generic where possible. >=20 > > And batteries have very different characteristics and vary between = devices=E2=80=A6 >=20 > Right. Maybe that has been already agreed on to use capacity-uah for > batteries in general? In that case I have not problem with that as > it's a generic property :) > =20 > > The charging maps are depending on the battery type connected to th= e twl4030 > > and which madc channel is which value is also a little hardware dep= endent > > (although the twl4030 doesn=E2=80=99t give much choice). >=20 > Just to consider alternatives before introducing driver specific > property for the maps.. Maybe here you could have few different type > of maps and select something safe by default? Of course it could be t= his > is higly board specific, I think some devices may be able to run belo= w > 3.3V for example.. As I explained in some other mail, those tables should not be neccessary at all. They can be computed from li-ion characteristics and internal resistance, and assumed current during charge and discharge. Running below 3.3V.. not really. At that point, the battery is really _empty_, and voltage is going down really really fast. Plus, you are damaging the battery at that point. Pavel --=20 (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses= /blog.html -- To unsubscribe from this list: send the line "unsubscribe devicetree" i= n the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html