From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexandre Belloni Subject: Re: [PATCH 2/2] rtc: pcf2127: add battery-low INTn generation Date: Wed, 3 Apr 2019 18:15:29 +0200 Message-ID: <20190403161529.GS22216@piout.net> References: <1554303165-24813-1-git-send-email-f.suligoi@asem.it> <1554303165-24813-2-git-send-email-f.suligoi@asem.it> <20190403150824.GO22216@piout.net> <452a4cf1410a41c8b6f767ac6258482e@asem.it> <20190403153143.GQ22216@piout.net> <20190403155654.GR22216@piout.net> <8367f68a023d468f8235810b0cf583bc@asem.it> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <8367f68a023d468f8235810b0cf583bc@asem.it> Sender: linux-kernel-owner@vger.kernel.org To: Flavio Suligoi Cc: Alessandro Zummo , Rob Herring , Mark Rutland , "linux-rtc@vger.kernel.org" , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" List-Id: devicetree@vger.kernel.org On 03/04/2019 16:09:14+0000, Flavio Suligoi wrote: > Hi, > > > On 03/04/2019 15:49:03+0000, Flavio Suligoi wrote: > > > > Then, you should probably not enable BLIE because this will cause > > issues > > > > with the alarm functionnality.. It is certainly enough to use > > > > RTC_VL_READ periodically. > > > > > > We use the nINT signaling solution because of this pin, in addition > > > to be used by the CPU, can be also connected to an external connector, > > > available for the final user. > > > Anyway, even if the BLIE is set, the sw low voltage alarm works, > > > with the message (displayed about every 12 minutes): > > > > > > > I agree the DT property makes sense when the nINT pin is not connected > > to the CPU. But if it is, then you have an issue that nINT will be > > pulled low until the user changes the battery, meaning that you will > > not get any alarm interrupt anymore, possibly leading to a system that > > is not waking up anymore. > > Ah, ok, thanks for the info. > I know this, but in our specific case, this is not a problem, > since we don't use the nINT for other purposes, but only for > a battery low indicator. On the contrary, in our case, it's better > that the alarm signal remains low until the battery is changed. > > Anyway, I can specify this collateral effect in a specific file for the > Pcf2127 in the DT bindings Documentation. What do you think? > This is fine as-is, I'll handle that in my series adding alarm support because there will be no issues until then. -- Alexandre Belloni, Bootlin Embedded Linux and Kernel engineering https://bootlin.com