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=-5.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_MUTT autolearn=ham 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 F0DCAC43387 for ; Fri, 21 Dec 2018 08:40:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B5FE1218FD for ; Fri, 21 Dec 2018 08:40:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linaro.org header.i=@linaro.org header.b="Ce3g6XgA" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388138AbeLUIkP (ORCPT ); Fri, 21 Dec 2018 03:40:15 -0500 Received: from mail-wm1-f67.google.com ([209.85.128.67]:55246 "EHLO mail-wm1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388072AbeLUIkP (ORCPT ); Fri, 21 Dec 2018 03:40:15 -0500 Received: by mail-wm1-f67.google.com with SMTP id a62so4480620wmh.4 for ; Fri, 21 Dec 2018 00:40:13 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to :user-agent; bh=tf1B/0sMesJfH+HmA4iAP0Sn3AZ4Gs7mp4+bQjMC6yQ=; b=Ce3g6XgAGR/pchMGQ49V8Snubp160RXDplkt9ta1jK2kH2sO+WZcC3B8EN0dCI4WHL sJK6r2sbKOs7a4xwnfWv+Gn8tHe5iHbdl2xT4JjUQ0C3Nd7KfjVi5Lh6WjfteGRturVK Y2QtwKsM22jiPp80nTFNc5Jo1HoQLteL1Uzck= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to:user-agent; bh=tf1B/0sMesJfH+HmA4iAP0Sn3AZ4Gs7mp4+bQjMC6yQ=; b=LDBb9hOmJtBDocGKgF0Qfw1zzHFd39N724mHx0VHwBmDUq2wx8dfiGgIWQkjcBm/c9 92UvMRmUMw0mQRYgdA1jHhxx2a0RVpW5AVy5a1MyBLbT3i7A3+maePFhKixbWJV7PxdI q0cY9DK2fmQlDEXRuiPrcsbjJHFOzoi9rQc5qI1T1Wy61onngXicH7xzfb5WLfrO+5Fn SXfixPr6+YR/QgOlWxS+lMtgqOtoGTHHDRYHnmP6fjCstrMTWVdjRS2H6ObucuGjuBZF a+iRQGKLYco6j/zVL4tTsnEG+h3qsjuEC5H8xyfRGS6PiYdd3b2GSCrawFJ4FBZBuCAf DICQ== X-Gm-Message-State: AJcUukcqkqyzNgc0izqEuH8YHNOkaapdsq+CbJ7zrer9//uoZS3USmJQ 4mHwr6IeCEaUjLe/BhrBsxjz5Q== X-Google-Smtp-Source: AFSGD/U8Jzgwv+Bcm/0I+KzdmlOpTvdbyXBiYapL5R7RxmdAi+gsNj7Q/b2HnmtfHaGIMmmt60IPgg== X-Received: by 2002:a1c:7f0c:: with SMTP id a12mr1790293wmd.89.1545381613189; Fri, 21 Dec 2018 00:40:13 -0800 (PST) Received: from dell ([95.149.164.119]) by smtp.gmail.com with ESMTPSA id x186sm8881966wmg.41.2018.12.21.00.40.12 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Fri, 21 Dec 2018 00:40:12 -0800 (PST) Date: Fri, 21 Dec 2018 08:40:10 +0000 From: Lee Jones To: Priit Laes Cc: Rob Herring , Mark Rutland , Chen-Yu Tsai , Maxime Ripard , Liam Girdwood , Mark Brown , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Olliver Schinagl , linux-sunxi Subject: Re: [PATCH v2 5/8] dt-bindings: mfd: axp20x: Add software based soft_start for AXP209 LDO3 Message-ID: <20181221084010.GR4497@dell> References: <25e67fe9b5397aa5f11bdd7026e4ae6be51dd18b.1544512919.git-series.plaes@plaes.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <25e67fe9b5397aa5f11bdd7026e4ae6be51dd18b.1544512919.git-series.plaes@plaes.org> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 11 Dec 2018, Priit Laes wrote: > From: Olliver Schinagl > > In the past, there have been words on various lists that if LDO3 is > disabled in u-boot, but enabled in the DTS, the axp209 driver would > fail to continue/hang. Several enable/disable patches have been > issues to devicetree's in both the kernel and u-boot to address > this issue. > > What really happened however, was that the AXP209 shuts down without > a notice and without setting an interrupt. This is caused when LDO3 > gets overloaded, for example with large capacitors on the LDO3 output. > > Normally, we would expect that AXP209 would source 200 mA as per > datasheet and set and trigger an interrupt when being overloaded. > For some reason however, this does not happen. > > As a work-around, implement software-based 'regulator-soft-start' > property for AXP209 LDO3 regulator, which is used to first bring up > the LDO3 to the lowest possible voltage and then enable the LDO. > > After that, we can set the requested voltage as usual. > > Combining this setting with the regulator-ramp-delay allows LDO3 to > come up slowly and staggered, potentially reducing overall inrush current. > > Signed-off-by: Olliver Schinagl > Signed-off-by: Priit Laes > --- > Documentation/devicetree/bindings/mfd/axp20x.txt | 3 +++ > 1 file changed, 3 insertions(+) For my own reference: Acked-for-MFD-by: Lee Jones -- Lee Jones [李琼斯] Linaro Services Technical Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog