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=-4.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 4F6C1C433DF for ; Mon, 27 Jul 2020 14:51:21 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 1C4A220775 for ; Mon, 27 Jul 2020 14:51:21 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="AptJMwZH" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1C4A220775 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=bootlin.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=MLFZiXSwcUXO/iv/fl3mEoDveIJlLpBomGAlhI79jfU=; b=AptJMwZHY+zu4hXfpl6xIZTXF ZtX8ER4VsX+2sexow7yns7x9NwrS8yZoAtshsXkteYT80h+DTYYa3OzZiC+5WBDHQeSpgBQfU7ZfW MDXd5pTjAE9Ro1oIAbPYy9Ig9wYdrv9YzmBYVS01MZtbjCjmrOCpLDi/U8wgAoZ1DIqXTbXtw8TOC +t4bELg94dw2HGyK0Si5fB5wmjVQ8lqkKvwnvDiUALozeh58Q63z6wXYb0JGS3g8H7e5oKbj4zZH0 1PZdN/lflSwh8LEWltOBFTP5DUR9kBW6lf1Y22C4hz492nCfRZd1aR7AzY2kDI/Q92oNznvb2Wjua l8x3F512w==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1k04Rm-0003Z7-BK; Mon, 27 Jul 2020 14:49:46 +0000 Received: from relay4-d.mail.gandi.net ([217.70.183.196]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1k04Rk-0003Ya-8l for linux-arm-kernel@lists.infradead.org; Mon, 27 Jul 2020 14:49:45 +0000 X-Originating-IP: 90.66.108.79 Received: from localhost (lfbn-lyo-1-1932-79.w90-66.abo.wanadoo.fr [90.66.108.79]) (Authenticated sender: alexandre.belloni@bootlin.com) by relay4-d.mail.gandi.net (Postfix) with ESMTPSA id 50C81E0019; Mon, 27 Jul 2020 14:49:38 +0000 (UTC) Date: Mon, 27 Jul 2020 16:49:38 +0200 From: Alexandre Belloni To: Russell King - ARM Linux admin Subject: Re: [PATCH v2 1/3] dt-bindings: rtc: pcf8523: add DSM pm option for battery switch-over Message-ID: <20200727144938.GC239143@piout.net> References: <20200719145028.3370-3-miguelborgesdefreitas@gmail.com> <20200720112401.4620-1-miguelborgesdefreitas@gmail.com> <20200720112401.4620-2-miguelborgesdefreitas@gmail.com> <20200723174905.GA596242@bogus> <20200723195755.GV3428@piout.net> <20200727094553.GH1551@shell.armlinux.org.uk> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200727094553.GH1551@shell.armlinux.org.uk> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200727_104944_417477_260EBE63 X-CRM114-Status: GOOD ( 18.62 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Rob Herring , baruch@tkos.co.il, kernel@pengutronix.de, a.zummo@towertech.it, festevam@gmail.com, s.hauer@pengutronix.de, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, linux-imx@nxp.com, miguelborgesdefreitas@gmail.com, shawnguo@kernel.org, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 27/07/2020 10:45:53+0100, Russell King - ARM Linux admin wrote: > > This is but this shouldn't be a DT property as it has to be changed > > dynamically. I'm working on an ioctl interface to change this > > configuration. > > Why does it need to be changed dynamically? If the hardware components > are not fitted to allow the RTC to be safely used without DSM, then > why should userspace be able to disable DSM? For RTCs with a standby mode, you want to be able to return to standby mode. That would happen for example after factory flashing in that common use case: - the board is manufactured - Vbackup is installed, the RTC switches to standby mode - the board is then booted to flash a system, Vprimary is now present, the RTC switches to DSM. At this point, if the board is simply shut down, the RTC will start draining Vbackup before leaving the factory. Instead, we want to be able to return to standby mode until the final user switches the product on for the first time. -- Alexandre Belloni, Bootlin Embedded Linux and Kernel engineering https://bootlin.com _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel