From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932454AbeCFMcP (ORCPT ); Tue, 6 Mar 2018 07:32:15 -0500 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:37550 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750897AbeCFMcN (ORCPT ); Tue, 6 Mar 2018 07:32:13 -0500 Cc: Amit Kucheria , devicetree@vger.kernel.org, Sudeep Holla , ilina@codeaurora.org, Zhang Rui , Eduardo Valentin , Rob Herring , Mark Rutland , linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] thermal: of: Allow selection of thermal governor in DT To: Ram Chandrasekar References: <3b80853abb45a9e067cf7a16754b07bb67712457.1520274879.git.amit.kucheria@linaro.org> From: Sudeep Holla Organization: ARM Message-ID: <6d5aeab8-aafe-fa3b-585e-953a34864e7d@arm.com> Date: Tue, 6 Mar 2018 12:32:08 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: <3b80853abb45a9e067cf7a16754b07bb67712457.1520274879.git.amit.kucheria@linaro.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/03/18 18:36, Amit Kucheria wrote: > From: Ram Chandrasekar > > There is currently no way for the governor to be selected for each thermal > zone in devicetree. How is that any different from cpufreq, cpuidle or devfreq subsystems ? > This results in the default governor being used for all > thermal zones even though no such restriction exists in the core code. > What restrictions ? > Add support for specifying the thermal governor to be used for a thermal > zone in the devicetree. Then what prevents us from doing the same for other subsystems with so called /inefficient default/ governors ? > The devicetree config should specify the governor > name as a string that matches any available governors. If not specified, we > maintain the current behaviour of using the default governor. If one is specified, can the user change it from sysfs ? If yes, then why do we need this binding at all ? If no, we are basically restricting, then what would happen if the DT was shipped with wrong governor specified because the firmware author didn't know about any other governor ? IMO, having this in DT is bad idea as it may cause more issues than gain. We already have sysfs support like other PM subsystems and userspace can deal with it. -- Regards, Sudeep