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=-0.6 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID 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 03443C5CFE7 for ; Tue, 10 Jul 2018 18:25:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B102C20883 for ; Tue, 10 Jul 2018 18:25:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="iqDjD1ku"; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="NZz6CHM7" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B102C20883 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732520AbeGJSZW (ORCPT ); Tue, 10 Jul 2018 14:25:22 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:42858 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732245AbeGJSZW (ORCPT ); Tue, 10 Jul 2018 14:25:22 -0400 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id 9828160B18; Tue, 10 Jul 2018 17:45:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1531244759; bh=jYPfHnneS3EXHeZYjnIRzT3dEqMxfmcNXd6Df4giv4w=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=iqDjD1kupvT1eC4k9IWVseo/n+x/fDdWIjpFWsSX2eKKlC/Fr2VcJSr4F3Jlan7An T8SpL183WXrg+poPEufx6pKjzTwUnB/AwGNDXTDEiQMwOxkzPN6UqOfWZgE3smzd72 oXLVdYq4MZWKqFUIXzg4NZQrBk/S2FESut66FdtE= Received: from [10.46.160.165] (i-global254.qualcomm.com [199.106.103.254]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: collinsd@smtp.codeaurora.org) by smtp.codeaurora.org (Postfix) with ESMTPSA id 627C760B14; Tue, 10 Jul 2018 17:45:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1531244758; bh=jYPfHnneS3EXHeZYjnIRzT3dEqMxfmcNXd6Df4giv4w=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=NZz6CHM7r2oUJQf2cv/NF3S6K0minrJlvxN+o1RBoB7ihIqitOKZvQwUrbIJvWmtZ N5ZJvJ5DfoqQojbr0Pl0QKmQd/FRazxrUWWHA4B5WaGcBW53qncpj+3q486pyvWekI hyafdus4pesMBWt1bOf4OQRC8PDGezqX/uU+L1io= DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 627C760B14 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=collinsd@codeaurora.org Subject: Re: [PATCH 3/3] arm64: dts: qcom: pm8998: Add thermal zone To: Matthias Kaehlcke Cc: Doug Anderson , Andy Gross , David Brown , Rob Herring , Mark Rutland , Catalin Marinas , Will Deacon , "open list:ARM/QUALCOMM SUPPORT" , linux-arm-msm , Linux ARM , LKML , Stephen Boyd References: <20180628210915.160893-1-mka@chromium.org> <20180628210915.160893-3-mka@chromium.org> <20180629185102.GV129942@google.com> <3b5054bb-76e4-a06f-54bb-e6ea7bbbcc69@codeaurora.org> <20180629235417.GY129942@google.com> From: David Collins Message-ID: <8144dd3c-6138-7f16-ec17-d75e84fcfb34@codeaurora.org> Date: Tue, 10 Jul 2018 10:45:57 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.1.1 MIME-Version: 1.0 In-Reply-To: <20180629235417.GY129942@google.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Matthias, On 06/29/2018 04:54 PM, Matthias Kaehlcke wrote: > On Fri, Jun 29, 2018 at 02:29:55PM -0700, David Collins wrote: ... >> The PMIC TEMP_ALARM hardware peripheral will perform an automatic partial >> PMIC shutdown upon hitting over-temperature stage 2 (125 C). This turns >> off peripherals within the PMIC that are expected to draw significant >> current. The set of peripherals included varies between PMICs. This >> partial shutdown will occur simultaneously with the triggering of an >> interrupt to the APPS processor that informs the qcom-spmi-temp-alarm >> driver that an over-temperature threshold has been crossed. >> >> The TEMP_ALARM peripheral will perform an automatic full PMIC shutdown >> upon hitting over-temperature stage 3 (145 C). Software won't receive an >> interrupt in this case because all power is cut. > > This information is very useful, thanks David! > > The (partial) hardware shutdown seems like a good measure of last > resort, however I suppose we prefer Linux to initiate a shutdown > before losing part of the peripherals (drivers might not be happy > about this and probably not revover even when the temperature goes > down again) or reach a full PMIC shutdown. > > Please let me know if there are reasons to prefer to go the hardware > limits, it's also an option for device makers to overwrite these > settings if they want different behavior. Disabling stage 3 automatic full PMIC shutdown at 145 C is definitely a bad idea. This exists as a last resort in order to save the hardware and ensure end user safety in case of excessive temperature even if software is locked up. Disabling stage 2 automatic partial PMIC shutdown at 125 C is not recommended as the PMIC is already outside of reasonable operating conditions and needs to take corrective action quickly. However, doing so may be acceptable if software is taking action to shut down the system immediately upon receiving the stage 2 over-temperature interrupt. Take care, David -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project