From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Machek Subject: Re: Should 9aafabc7fece be reverted? Date: Fri, 20 May 2016 11:29:27 +0200 Message-ID: <20160520092927.GB4580@amd> References: <573C9F45.5090109@ti.com> <201605191806.50809@pali> <573DE5A2.7070900@ti.com> <201605191818.20237@pali> <573DEDFF.8060305@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:53929 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751971AbcETJ3a (ORCPT ); Fri, 20 May 2016 05:29:30 -0400 Content-Disposition: inline In-Reply-To: <573DEDFF.8060305@ti.com> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: "Andrew F. Davis" Cc: Pali =?iso-8859-1?Q?Roh=E1r?= , Ivaylo Dimitrov , Sebastian Reichel , Dmitry Eremin-Solenikov , David Woodhouse , linux-pm@vger.kernel.org Hi! > >>>>> No, it is not driver name, but device name. That is different. > >>>> > >>>> My bad, that's what I meant, device names should be dynamic, > >>>> right? Relying on them being static in software would then be > >>>> buggy (like relying on eth0 being the right NIC everytime)? > >>>> > >>>> I'm not familiar with the N900 software, but IDR can give out > >>>> different numbers and may not always give the first battery #0 (it > >>>> does now but is that a guarantee in IDR?) and if not then what is > >>>> the userspace response to this changing? > >>> > >>> In case N900 would have more bq27xxx batteries, then yes. But N900 > >>> has exactly *one* bq27200 battery, so there is no IDR problem. > >> > >> Right, but if IDR returns 42 instead of 0 would this then break its > >> userspace software? > > > > I think it is insane to starts generating random numbers for IDR... Hard > > to decide what happen if such situation occur... > > > > That's kind of what I'm looking for though, if the userspace break is > caused by software relying on the battery to be named "bq27200-0", then > nothing short of hard-coding this exact name will 100% safely fix the > N900 userspace software. And so using IDR and hoping it gives 0 is just > a hacky work-around way of just naming the device "bq27200-0". N900 userspace is not intended to be portable. (And actually current kernel support does not allow writing portable userspace for a phone. It presents _3_ power supplies to userspace. How is userspace expected to deal with that?) And if you ever name the single battery bq27200-42 or bq27200-1337, you'll have a flock of angry penguins at your doorstep. Best regards, Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html