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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D43B4C433EF for ; Thu, 2 Jun 2022 09:16:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232875AbiFBJQa (ORCPT ); Thu, 2 Jun 2022 05:16:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48940 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232836AbiFBJQ3 (ORCPT ); Thu, 2 Jun 2022 05:16:29 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 0B18912612; Thu, 2 Jun 2022 02:16:27 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id A39781063; Thu, 2 Jun 2022 02:16:27 -0700 (PDT) Received: from [10.57.38.114] (unknown [10.57.38.114]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 309D93F766; Thu, 2 Jun 2022 02:16:26 -0700 (PDT) Message-ID: Date: Thu, 2 Jun 2022 10:16:23 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.8.1 Subject: Re: [PATCH 3/3] thermal/sysfs: Remove cooling device sysfs statistics Content-Language: en-US To: Daniel Lezcano Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, rafael@kernel.org, quic_manafm@quicinc.com, Amit Kucheria , Zhang Rui , Todd Kjos References: <20220601151441.9128-1-daniel.lezcano@linaro.org> <20220601151441.9128-3-daniel.lezcano@linaro.org> From: Lukasz Luba In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 6/2/22 09:37, Daniel Lezcano wrote: > > Hi Lukasz, > > [Adding Todd] > > On 01/06/2022 17:33, Lukasz Luba wrote: >> Hi Daniel, >> >> >> On 6/1/22 16:14, Daniel Lezcano wrote: >>> The statistics are for debugging purpose and belong to debugfs rather >>> than sysfs. As the previous changes introduced the same statistics in >>> debugfs, those in sysfs are no longer needed and can be removed. >> >> I just want to let you know that in current Android kernels we cannot >> even compile the kernel with CONFIG_DEBUG_FS. > > Right, it makes sense. Precisely, with the sysfs stats they are always > compiled in for the Android kernel and is a problem for low memory > systems. While debugfs can fulfill its purpose in the developement and > will be removed in production systems. True. > >> I have this pain with >> Energy Model there... Some vendors might see useful info via this >> sysfs interface in bring-up of the SoC. > > Well alternatively, information can be extracted from procfs in the > device-tree description. > > What prevents to add energy information in sysfs now that the energy > model is per device ? Probably nothing, but we need strong need. I have proposed this a few times internally, but this must have a requirement. If a user-space tool would ask for it, then I could send a patch exposing the sysfs. So far we have only one user-space tool, which suffers the missing debugfs EM dir: LISA (but we are working on a workaround for it). If you have a tool or plan to have such, which uses EM, please let me know. I'm gathering the requirements. > >> I don't know if there are user-space tools tracking this >> information via sysfs. We probably should check that. >> >> I agree that these statistics look more like debug info, rather than >> something useful for control. >> >> Furthermore, we have trace events for the cooling state changes, which >> should be good enough for bring-up and experiments. >> >> I don't have strong preferences here. I tend to agree to remove this >> interface if there are no user-space tools using it. > > I agree userspace can also get information about the transition but the > goal of the debugfs is also add information about thermal internals like > average temperature at mitigation time, min and max, timings, etc ... > > I see, it makes sense. Let's see if Todd and Android folks don't use this thermal sysfs stats, so we could remove them.