From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A6116C4360F for ; Wed, 3 Apr 2019 15:31:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6EC5C206DD for ; Wed, 3 Apr 2019 15:31:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726412AbfDCPbs (ORCPT ); Wed, 3 Apr 2019 11:31:48 -0400 Received: from relay5-d.mail.gandi.net ([217.70.183.197]:34327 "EHLO relay5-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725990AbfDCPbr (ORCPT ); Wed, 3 Apr 2019 11:31:47 -0400 X-Originating-IP: 109.213.83.19 Received: from localhost (alyon-652-1-60-19.w109-213.abo.wanadoo.fr [109.213.83.19]) (Authenticated sender: alexandre.belloni@bootlin.com) by relay5-d.mail.gandi.net (Postfix) with ESMTPSA id 368601C0004; Wed, 3 Apr 2019 15:31:44 +0000 (UTC) Date: Wed, 3 Apr 2019 17:31:43 +0200 From: Alexandre Belloni To: Flavio Suligoi Cc: Alessandro Zummo , Rob Herring , Mark Rutland , "linux-rtc@vger.kernel.org" , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH 2/2] rtc: pcf2127: add battery-low INTn generation Message-ID: <20190403153143.GQ22216@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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <452a4cf1410a41c8b6f767ac6258482e@asem.it> User-Agent: Mutt/1.11.3 (2019-02-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/04/2019 15:14:24+0000, Flavio Suligoi wrote: > Hi Alexandre, > > > On 03/04/2019 16:52:45+0200, Flavio Suligoi wrote: > > > The pcf2127 has an automatic battery-low detection function. > > > > > > In case of battery-low event, an interrupt generation through > > > the pin INTn (active low) can be enabled, setting the flag BLIE > > > in the register Control_3. > > > > > > This function is activated by the "battery-low-hw-alarm" DT property. > > > > > > Example of use for an NXP i.MX7D board: > > > > > > &i2c3 { > > > clock-frequency = <100000>; > > > pinctrl-names = "default"; > > > pinctrl-0 = <&pinctrl_i2c3>; > > > status = "okay"; > > > > > > pcf2127@51 { > > > compatible = "nxp,pcf2127"; > > > reg = <0x51>; > > > battery-low-hw-alarm; > > > status = "okay"; > > > }; > > > }; > > > > > > > So I'm curious, how do you then use that signal? I have a (not yet sent) > > series adding alarm support for the pcf2127. The issue having BLIE is > > that then this will prevent the alarm to work properly. > > > > So my guess is that you have nINT connected to an LED or something that > > the user can see? > > > > I'm working on our custom embedded board with an NXP i.MX7D, > developed here, in Asem (www.asem.it). > The nINT pin is connected to a GPIO of the MX7 and then > used by an applicative sw, to generate an alarm for the user. > 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. -- Alexandre Belloni, Bootlin Embedded Linux and Kernel engineering https://bootlin.com