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=-10.0 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 33ABFC433E3 for ; Mon, 27 Jul 2020 14:53:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 097D2207BB for ; Mon, 27 Jul 2020 14:53:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=solid-run-com.20150623.gappssmtp.com header.i=@solid-run-com.20150623.gappssmtp.com header.b="pq5TkMXO" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730340AbgG0Oxh (ORCPT ); Mon, 27 Jul 2020 10:53:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42222 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728743AbgG0Oxg (ORCPT ); Mon, 27 Jul 2020 10:53:36 -0400 Received: from mail-ej1-x643.google.com (mail-ej1-x643.google.com [IPv6:2a00:1450:4864:20::643]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 61FDFC061794 for ; Mon, 27 Jul 2020 07:53:36 -0700 (PDT) Received: by mail-ej1-x643.google.com with SMTP id f14so1514082ejb.2 for ; Mon, 27 Jul 2020 07:53:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=solid-run-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=jCQp04gaUj6KkSnmOynTN5DWIdoTsVqJqWxUkHbzffI=; b=pq5TkMXOQlAMMfmLjbyxYb5ODxbZOaUIvr98CgMAX+JRzkZXMXVCqNbI0PnrVM/8Ii +YPP+5B9ghuK0TO845Bv6JhjHvj2rM3UMlRbrF36R4ql2z6nDxX9CJV8Ufa1ALYIGdWG czoOmvTHFSjFGN5lnQ2hZv8t8wJ6jKhoE/ZmogrWKtHRH9/LxX2tChA0K4dKKDFARJ8K ysM36eVGT7/R94eoeeDlcDOKtyYNlY9YC/sEOd5uJLXWwmqzu1qmRIMfAPiECZ4DZHVH KUIPzPwaKL38NQWH1VYkUlwNxotUxis5blXXICAWS04m7R1ecgEwHSzM7QGidgXpmQAx onKg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=jCQp04gaUj6KkSnmOynTN5DWIdoTsVqJqWxUkHbzffI=; b=RPXkj3yOh/DVqbin4nS7DJrt4CPJ/YLlkMNhGFsvwC6cnCmPxH11hYABQvaZsHWKAe Vysn9FMe87Y/Z/Hm1HzWnMisxgxKb4ykG8s5CuG+vAiapuVERlfwGbQaQ8AdOvF3/oFm yIdGKT5InLw7+xPMGttkNb12Z7N3tMM+d68DoLe0RQCxrWRCIg0iCR2L9K73Z8i4TUhA 4K6DRr/jAV3OGKReN2DJbaF2zHziDaMtU7Gpr55uNQ8Yiwq60SqbRb0ck/188RHlfuVg HXzWycPY4UUb9zH56mJwd++7xQ33JJT0rwpk9E77OMe5jCsM0ASNjrP4mZSwkmUrxVsE G14g== X-Gm-Message-State: AOAM530ykQaDPUXrRF3xPGfNrGKs6cnPNR4F/cz7DsGGizIuByqPMuTi qc+gdkQPnA1X7cc2wWxNtVthrG5K24DHbarPqzWWzg== X-Google-Smtp-Source: ABdhPJy7XLns5nLG05OdBbUylSemksWFr2TLHaYF566wq5VWjAAx+FLLYE2WnV0UslxIVf7mRgpoCwhY5w/gyXEARqQ= X-Received: by 2002:a17:906:600f:: with SMTP id o15mr6513709ejj.41.1595861615025; Mon, 27 Jul 2020 07:53:35 -0700 (PDT) MIME-Version: 1.0 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> <20200727141729.GJ1551@shell.armlinux.org.uk> In-Reply-To: <20200727141729.GJ1551@shell.armlinux.org.uk> From: Jon Nettleton Date: Mon, 27 Jul 2020 16:52:58 +0200 Message-ID: Subject: Re: [PATCH v2 1/3] dt-bindings: rtc: pcf8523: add DSM pm option for battery switch-over To: Russell King - ARM Linux admin 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 Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 27, 2020 at 4:17 PM Russell King - ARM Linux admin wrote: > > 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. > Agreed. Do we need a modes supported device-tree property? That would actually describe the hardware as device-tree is supposed to do. 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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=jCQp04gaUj6KkSnmOynTN5DWIdoTsVqJqWxUkHbzffI=; b=BZMDmHLyofzVUxZ/AOs5HnnATtQ1Pj+8RCdrUAuefsQoQlB9XnivBtd2th/hG0VTuv NNrdM2jnTlyJM0I/gzDzTfhs5wYAXLxXTU1lTUUri1JXQgGbRTof68BiY+NQ9nYlVc/l z/t68ia+HWMJlL+Ni0ikeLt82s5Ruyr/5R1XXXIMcaNic94+a408HF750IccldzHla4j wouGCQVawyTI437yfudH7vy82CguD0r1UmzFm1r6ACJ09ijcaIUz5YpWTXM1D9/W3aIL 3dmv/qvrSBErPbyFTvSbHQiDt9QO3rFwr2DDB/hlRCYPZqpwAGPVwy+4zcLJmSHDmVst sO+w== X-Gm-Message-State: AOAM533Yo/Lyb2B1bK+VXTzopFCTZ/dUKO6lMBtf8GHaIg5G5bhkYMuf nYlDPuTrYA3hsSdluZTDATY9y/rKClCITwmYkAeM9g== X-Google-Smtp-Source: ABdhPJy7XLns5nLG05OdBbUylSemksWFr2TLHaYF566wq5VWjAAx+FLLYE2WnV0UslxIVf7mRgpoCwhY5w/gyXEARqQ= X-Received: by 2002:a17:906:600f:: with SMTP id o15mr6513709ejj.41.1595861615025; Mon, 27 Jul 2020 07:53:35 -0700 (PDT) MIME-Version: 1.0 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> <20200727141729.GJ1551@shell.armlinux.org.uk> In-Reply-To: <20200727141729.GJ1551@shell.armlinux.org.uk> From: Jon Nettleton Date: Mon, 27 Jul 2020 16:52:58 +0200 Message-ID: Subject: Re: [PATCH v2 1/3] dt-bindings: rtc: pcf8523: add DSM pm option for battery switch-over To: Russell King - ARM Linux admin X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200727_105337_947611_D9A2A2B0 X-CRM114-Status: GOOD ( 38.56 ) 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 , Alexandre Belloni , Miguel Borges de Freitas , a.zummo@towertech.it, Shawn Guo , Sascha Hauer , Baruch Siach , Linux Kernel Mailing List , devicetree , NXP Linux Team , Sascha Hauer , Fabio Estevam , linux-arm-kernel 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 Mon, Jul 27, 2020 at 4:17 PM Russell King - ARM Linux admin wrote: > > 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. > Agreed. Do we need a modes supported device-tree property? That would actually describe the hardware as device-tree is supposed to do. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel