From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753389AbbCaH04 (ORCPT ); Tue, 31 Mar 2015 03:26:56 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:60896 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753276AbbCaH0r (ORCPT ); Tue, 31 Mar 2015 03:26:47 -0400 Date: Tue, 31 Mar 2015 09:26:43 +0200 From: Pavel Machek 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@vger.kernel.org, LKML , linux-omap@vger.kernel.org, linux-arm-kernel , linux-pm@vger.kernel.org Subject: Re: [PATCH v4 3/6] Documentation: DT: Document twl4030-madc-battery bindings 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-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20150311164442.GA5264@atomide.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi! > > >> + io-channels = <&twl_madc 1>, > > >> + <&twl_madc 10>, > > >> + <&twl_madc 12>; > > >> + io-channel-names = "temp", > > >> + "ichg", > > >> + "vbat"; > > >> + }; > > > > > > Rather than just making platform_data into device tree properties.. > > > > > > Can't you hide the these custom properties behind the compatible flag? > > > > > > You can initialize that data in the driver based on the compatible > > > flag and the match data. > > > > > > This makes sense if you can group things to similar configurations. > > > > Maybe I have not completely understood your proposal. > > > > 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. compatible = “board17”) > > chooses the right data set for the charging map and channels? > > If you can somehow group them, then yes. Not for every board if there > are many of them naturally. > > > I thought this is what the DT was introduced for - to have the same driver > > code but adapt to different boards depending on hardware variations. > > 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. > > > And batteries have very different characteristics and vary between devices… > > 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 :) > > > The charging maps are depending on the battery type connected to the twl4030 > > and which madc channel is which value is also a little hardware dependent > > (although the twl4030 doesn’t give much choice). > > 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 this > is higly board specific, I think some devices may be able to run below > 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 -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html