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=-11.3 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 96C3DC433E5 for ; Mon, 27 Jul 2020 14:17:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 755B32070A for ; Mon, 27 Jul 2020 14:17:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b="scf1g10G" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731106AbgG0ORp (ORCPT ); Mon, 27 Jul 2020 10:17:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36278 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731101AbgG0ORm (ORCPT ); Mon, 27 Jul 2020 10:17:42 -0400 Received: from pandora.armlinux.org.uk (pandora.armlinux.org.uk [IPv6:2001:4d48:ad52:32c8:5054:ff:fe00:142]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4D622C061794; Mon, 27 Jul 2020 07:17:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2019; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=bjl5+gq9U2Z2bSaiJfRP1zE+wAOWJevhrAxgUgYzigo=; b=scf1g10GNIN9R7N3bdXIm5T3X V8f6RnSM/4Xa9NqtWNHxFbujD3DawFPmJEdB5C+0xf/QAPOHOsbAVsy0lJnPB1QBEd633qDI+ASX1 U2BvCGMKw5OL+Bn8VyhCXqKOjnxsoOl9q16TV9mYn+uTAStQNaJHeOrSRu9KoC/RmVTnlrnFHl3+3 76hmuHXIOSDej96ZKbi0/+GxDswQdm4PLsUcFMOO0imklYud/ud8/7J9zrPKGJ4Z6nuMos5KuT8Gi EdoJyBJA/6npMLkE57eHlhGosxv68mTqP/rgd1RON+dMfXYJeqj0K0LLyowzgJ4hJlAVwyqjXylAI IWXbxI4xQ==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:44830) by pandora.armlinux.org.uk with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1k03wa-0002xY-0h; Mon, 27 Jul 2020 15:17:32 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.92) (envelope-from ) id 1k03wX-0003ir-Gd; Mon, 27 Jul 2020 15:17:29 +0100 Date: Mon, 27 Jul 2020 15:17:29 +0100 From: Russell King - ARM Linux admin To: Jon Nettleton Cc: Rob Herring , Alexandre Belloni , Sascha Hauer , a.zummo@towertech.it, Fabio Estevam , Sascha Hauer , Baruch Siach , Linux Kernel Mailing List , devicetree , NXP Linux Team , Miguel Borges de Freitas , Shawn Guo , linux-arm-kernel Subject: Re: [PATCH v2 1/3] dt-bindings: rtc: pcf8523: add DSM pm option for battery switch-over Message-ID: <20200727141729.GJ1551@shell.armlinux.org.uk> 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-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Mon, Jul 27, 2020 at 03:33:17PM +0200, Jon Nettleton wrote: > On Mon, Jul 27, 2020 at 11:46 AM Russell King - ARM Linux admin > wrote: > > > > On Thu, Jul 23, 2020 at 09:57:55PM +0200, Alexandre Belloni wrote: > > > On 23/07/2020 11:49:05-0600, Rob Herring wrote: > > > > On Mon, Jul 20, 2020 at 12:23:59PM +0100, miguelborgesdefreitas@gmail.com wrote: > > > > > From: Miguel Borges de Freitas > > > > > > > > > > This adds direct-switching mode as a configurable DT flag for > > > > > RTC modules supporting it (e.g. nxp pcf8523). > > > > > DSM switches the power source to the battery supply whenever the > > > > > VDD drops below VBAT. The option is recommended for hw designs > > > > > where VDD is always expected to be higher than VBAT. > > > > > > > > > > Signed-off-by: Miguel Borges de Freitas > > > > > --- > > > > > Changes in v2: > > > > > - Added extended commit message for git history > > > > > - Separate dt bindings documentation into a single patch > > > > > > > > > > Documentation/devicetree/bindings/rtc/nxp,pcf8523.txt | 7 ++++++- > > > > > Documentation/devicetree/bindings/rtc/rtc.yaml | 7 +++++++ > > > > > 2 files changed, 13 insertions(+), 1 deletion(-) > > > > > > > > > > diff --git a/Documentation/devicetree/bindings/rtc/nxp,pcf8523.txt b/Documentation/devicetree/bindings/rtc/nxp,pcf8523.txt > > > > > index 0b1080c..f715a8f 100644 > > > > > --- a/Documentation/devicetree/bindings/rtc/nxp,pcf8523.txt > > > > > +++ b/Documentation/devicetree/bindings/rtc/nxp,pcf8523.txt > > > > > @@ -4,10 +4,14 @@ Required properties: > > > > > - compatible: Should contain "nxp,pcf8523". > > > > > - reg: I2C address for chip. > > > > > > > > > > -Optional property: > > > > > +Optional properties: > > > > > - quartz-load-femtofarads: The capacitive load of the quartz(x-tal), > > > > > expressed in femto Farad (fF). Valid values are 7000 and 12500. > > > > > Default value (if no value is specified) is 12500fF. > > > > > +- pm-enable-dsm: battery switch-over function is enabled in direct > > > > > + switching mode. The power failure condition happens when VDD < VBAT, > > > > > + without requiring VDD to drop below Vth(sw)bat. > > > > > + Default value (if not provided) is the standard mode. > > > > > > > > > > Example: > > > > > > > > > > @@ -15,4 +19,5 @@ pcf8523: rtc@68 { > > > > > compatible = "nxp,pcf8523"; > > > > > reg = <0x68>; > > > > > quartz-load-femtofarads = <7000>; > > > > > + pm-enable-dsm; > > > > > }; > > > > > diff --git a/Documentation/devicetree/bindings/rtc/rtc.yaml b/Documentation/devicetree/bindings/rtc/rtc.yaml > > > > > index ee237b2..a0048f4 100644 > > > > > --- a/Documentation/devicetree/bindings/rtc/rtc.yaml > > > > > +++ b/Documentation/devicetree/bindings/rtc/rtc.yaml > > > > > @@ -47,4 +47,11 @@ properties: > > > > > description: > > > > > Enables wake up of host system on alarm. > > > > > > > > > > + pm-enable-dsm: > > > > > + $ref: /schemas/types.yaml#/definitions/flag > > > > > + description: > > > > > + Enables the battery switch-over function in direct switching > > > > > + mode. Should be set in systems where VDD is higher than VBAT > > > > > + at all times. > > > > > > > > I'm all for common properties, but is this common across vendors? > > > > > > > > > > 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? > > > > My presumption would be if you had a system that ran at different > system voltages depending if it is plugged in to mains or running on a > battery. Yes, but we're not talking about that case with the Cubox-i. Should a platform like the Cubox-i allow the user to disable DSM? There needs to be a way to block the ability to dynamically change this mode if the hardware is not up to operating without DSM. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!