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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 C3E96C6778C for ; Tue, 3 Jul 2018 17:13:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 78CF920C0B for ; Tue, 3 Jul 2018 17:13:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="lvwITouF" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 78CF920C0B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=chromium.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 S934242AbeGCRNd (ORCPT ); Tue, 3 Jul 2018 13:13:33 -0400 Received: from mail-pg0-f67.google.com ([74.125.83.67]:43355 "EHLO mail-pg0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933960AbeGCRN1 (ORCPT ); Tue, 3 Jul 2018 13:13:27 -0400 Received: by mail-pg0-f67.google.com with SMTP id v13-v6so1262130pgr.10 for ; Tue, 03 Jul 2018 10:13:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=V+Hu1q0PLFbR/vIYabfV+u580j8aAvB27Y6v/AzHNHU=; b=lvwITouFaNX0cgjEVO/Sq4L56HZr1FkXtgZYSRaWrxpHL1t7tY8ms5sBuWIMx8TNqf 3ubcO11G2DBwS6n+alwAA7ZSobf5UTmlmSCHsVAyRZKnO3LMITSRuTFaWe6aAnCVmMop v72vvN+j1zs/yA5j4Xk7cxitijHLcByucVG6U= 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:in-reply-to:user-agent; bh=V+Hu1q0PLFbR/vIYabfV+u580j8aAvB27Y6v/AzHNHU=; b=B9T+AkZuLpdp0D4eR9lj6vzgdRLOxX/fC5Z4oI7hOlUWQUsOb063SjL/KNN6ZjNfQp AqdzbJ+BPDxDG3ixUet3XsphhXy8jDNqXu8sqnpnsV/MZZEwIOoL/E3bq88UNTH2HrgE kjvBD3yGwKB7JGsbfs+iSawnbC4xisxZtnbVXxZ+gtagOP5uPa+Vf8qgTsydioISHmMA 2xU6u3Q1a0O8vEWLDoL4eVeIDhKNpEiyZJHYAdvHBbR4adZuLdX7fcBi/iUPy6lC6Vza Ounh4nh9wPsjL7Ud8maGLGvY12ZlgH6zli4ljCP6gM1pQ3thVeNDRAZdJ5vzX9/Xn9HR JDiQ== X-Gm-Message-State: APt69E3hBzYz4kpJWyhJ4LTBLInJkcEPX+be/vpPl5tNXolP4vME6Jbf srcx7FmXQ/C/bdDf36adHydPYQ== X-Google-Smtp-Source: ADUXVKJY86ndCuOZofPisED2lbouqmD2NgyjLqQcXwSdQ/EQJS9DnuTDPG0LhLMGhJqcTvPVtrAIIA== X-Received: by 2002:a65:4a92:: with SMTP id b18-v6mr25960927pgu.107.1530638006631; Tue, 03 Jul 2018 10:13:26 -0700 (PDT) Received: from localhost ([2620:0:1000:1501:8e2d:4727:1211:622]) by smtp.gmail.com with ESMTPSA id r4-v6sm5771799pfj.53.2018.07.03.10.13.25 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 03 Jul 2018 10:13:25 -0700 (PDT) Date: Tue, 3 Jul 2018 10:13:25 -0700 From: Matthias Kaehlcke To: Enric Balletbo i Serra Cc: rui.zhang@intel.com, rjw@rjwysocki.net, groeck@chromium.org, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, snanda@chromium.org, lenb@kernel.org, Eduardo Valentin , linux-pm@vger.kernel.org Subject: Re: [RESEND PATCH v3 2/2] thermal: core: introduce thermal zone device mode control Message-ID: <20180703171325.GC129942@google.com> References: <20180226144118.24693-1-enric.balletbo@collabora.com> <20180226144118.24693-2-enric.balletbo@collabora.com> <20180629003302.GT129942@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20180629003302.GT129942@google.com> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 28, 2018 at 05:33:02PM -0700, Matthias Kaehlcke wrote: > Hi, > > I stumbled across this patch since I'm currently poking around with > early thermal bringup on a platform and this patch has been integrated > in our development tree. > > I'm seeing some unexpected behaviors, which could entirely due to > wrong expectation from my side. I only have some basic working > knowledge of the thermal framework, just want to double check and > perhaps learn a thing or two. > > On Mon, Feb 26, 2018 at 03:41:18PM +0100, Enric Balletbo i Serra wrote: > > From: Zhang Rui > > > > Thermal "mode" sysfs attribute is introduced to enable/disable a thermal > > zone, and .get_mode()/.set_mode() callback is introduced for platform > > thermal driver to enable/disable the hardware thermal control logic. And > > thermal core takes no action upon thermal zone enable/disable. > > > > Actually, this is not quite right because thermal core still pokes those > > disabled thermal zones occasionally, e.g. upon system resume. > > > > To fix this, a new flag 'mode' is introduced in struct thermal_zone_device > > to represent the thermal zone mode, and several decisions have been made > > based on this flag, including > > 1. check the thermal zone mode right after it's registered. > > 2. skip updating thermal zone if the zone is disabled > > 3. stop the polling timer when the thermal zone is disabled > > > > Note: basically, this patch doesn't affect the existing always-enabled > > thermal zones much, with just one exception - > > thermal zone .get_mode() must be well prepared to reflect the real thermal > > zone status upon the thermal zone registration. > > From my perspective this looks like a pretty significant change. For > the platform I'm working on I added a thermal zone to the device tree, > with the expectation that it would be enabled. Judging from the code > without this patch this expectation seems to be naive, since > of-thermal.c sets tz->mode to THERMAL_DEVICE_DISABLED, so apparently > either userspace or some driver should call _set_mode(tz, > THERMAL_DEVICE_ENABLED). However even without this the thermal zone > appears to be active (I didn't really test end-to-end yet, but at > least thermal_zone_device_update() is called and calls > handle_thermal_trip()). Not sure why this is the case with > THERMAL_DEVICE_DISABLED, but before I learned about the existence of > the flag my expectation was that the zone would be enabled. > > With this patch thermal_zone_device_update() is skipped if the zone > hasn't been explictly enabled, which may be consistent with the state > of 'tz->mode', but effectively changes the previous/current behavior. > > Not sure if I'm just dumbly overlooking something obvious or if there > is an actual problem with of_thermal (and maybe others). The problem is that there are now two 'mode' fields, tzd->mode and the other typically tzd->devdata->mode, and tzd->mode is never set to enabled. > thermal zone .get_mode() must be well prepared to reflect the real thermal > zone status upon the thermal zone registration. For of_thermal tzd->mode is initialized with the result of .get_mode() when the zone is registered. At this time no sensor has been added to the zone, hence the zone is disabled. When a sensor is added later tzd->devdata->mode is set to enabled, however tzd->mode remains disabled: tzd->mode = DISABLED tzd->devdata->mode = DISABLED of_parse_thermal_zones thermal_zone_device_register tzd->mode = tzd->get_mode() // => DISABLED _probe thermal_zone_of_sensor_register tzd->set_mode(THERMAL_DEVICE_ENABLED) tzd->devdata->mode = ENABLED One way to fix this for of_thermal could be to setting tzd->mode in .set_mode() in addition to setting tzd->devdata->mode. However this feels like a workaround/hack. Personally I find it confusing to have two mode fields for a thermal zone device. Maybe tzd->mode should replace tzd->devdata->mode?