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=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 75CC7C2D0C8 for ; Thu, 12 Dec 2019 07:34:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4BED222527 for ; Thu, 12 Dec 2019 07:34:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576136088; bh=XtgX0cs3LO559cZljj3C1HKQa7WygDdwZ/aXLdtuvzY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=mUsIwrgqWBkkyb8HhPOmpmJxRHAZ1Felv/4txJT58d7AAVvjCfNaog+NiuihgD0i3 6GMkrpMUYiakMe+TMw08yhI8IqSDfWEsi5H2Fy+iRc0IITxPpId33L2LbACHMLL1Q7 ZinW1peyl3HjWkzdnkxIaD4W5UiviJYSDIMgXeLU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728179AbfLLHer (ORCPT ); Thu, 12 Dec 2019 02:34:47 -0500 Received: from mail.kernel.org ([198.145.29.99]:58464 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728096AbfLLHeq (ORCPT ); Thu, 12 Dec 2019 02:34:46 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id AC65122527; Thu, 12 Dec 2019 07:34:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576136085; bh=XtgX0cs3LO559cZljj3C1HKQa7WygDdwZ/aXLdtuvzY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=F4qpun/l7qSb7z6SG45XfI5PKUh/JUO02JDrkrX7C+cpGpUAQB3ylwJbzFBaW7ZZh hkJbfth9xaGQbk1khSVqlDlSYYaNpVnDzS43O4/ePBM4ky50vJirKybedl3zBN8Lk6 2SPXHCDuDfQnF7yZMHI7Vh4Xy1Pexy51XOay15bk= Date: Thu, 12 Dec 2019 08:34:43 +0100 From: Greg Kroah-Hartman To: Wei Wang Cc: Daniel Lezcano , Wei Wang , Zhang Rui , Eduardo Valentin , Amit Kucheria , Linux PM list , LKML , "Rafael J. Wysocki" Subject: Re: [PATCH v3 0/3] thermal: introduce by-name softlink Message-ID: <20191212073443.GC1364286@kroah.com> References: <20191205071953.121511-1-wvw@google.com> <69dd3a7a-c5fe-3ae7-8a4d-c3939870eed8@linaro.org> <0603228e-5f0b-d335-30ce-67cf0626a489@linaro.org> <20191211085400.GB500800@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 11, 2019 at 12:11:53PM -0800, Wei Wang wrote: > On Wed, Dec 11, 2019 at 12:54 AM Greg Kroah-Hartman > wrote: > > > > On Tue, Dec 10, 2019 at 09:54:11PM +0100, Daniel Lezcano wrote: > > > On 10/12/2019 21:01, Wei Wang wrote: > > > > On Tue, Dec 10, 2019 at 6:36 AM Daniel Lezcano > > > > wrote: > > > >> > > > >> On 05/12/2019 08:19, Wei Wang wrote: > > > >>> The paths thermal_zone%d and cooling_device%d are not intuitive and the > > > >>> numbers are subject to change due to device tree change. This usually > > > >>> leads to tree traversal in userspace code. > > > > tree traversal is supposed to be done in userspace code :) > > > Yes, that can be done in userspace, but given the amount of thermal > zones we have in some mobile devices, this will bring a lot of > convenience. Userspace is easier to write than kernel code. Kernel code and apis you have to retain for the next 20+ years, are you willing to do that? > e.g. this is on Pixel 4 XL: > coral:/ # ls /sys/devices/virtual/thermal/ > cdev-by-name cooling_device15 cooling_device22 cooling_device3 > cooling_device9 thermal_zone15 thermal_zone22 thermal_zone3 > thermal_zone37 thermal_zone44 thermal_zone51 thermal_zone59 > thermal_zone66 thermal_zone73 thermal_zone80 thermal_zone88 > cooling_device0 cooling_device16 cooling_device23 cooling_device30 > thermal_zone0 thermal_zone16 thermal_zone23 thermal_zone30 > thermal_zone38 thermal_zone45 thermal_zone52 thermal_zone6 > thermal_zone67 thermal_zone74 thermal_zone81 thermal_zone9 > cooling_device1 cooling_device17 cooling_device24 cooling_device31 > thermal_zone1 thermal_zone17 thermal_zone24 thermal_zone31 > thermal_zone39 thermal_zone46 thermal_zone53 thermal_zone60 > thermal_zone68 thermal_zone75 thermal_zone82 tz-by-name > cooling_device10 cooling_device18 cooling_device25 cooling_device4 > thermal_zone10 thermal_zone18 thermal_zone25 thermal_zone32 > thermal_zone4 thermal_zone47 thermal_zone54 thermal_zone61 > thermal_zone69 thermal_zone76 thermal_zone83 > cooling_device11 cooling_device19 cooling_device26 cooling_device5 > thermal_zone11 thermal_zone19 thermal_zone26 thermal_zone33 > thermal_zone40 thermal_zone48 thermal_zone55 thermal_zone62 > thermal_zone7 thermal_zone77 thermal_zone84 > cooling_device12 cooling_device2 cooling_device27 cooling_device6 > thermal_zone12 thermal_zone2 thermal_zone27 thermal_zone34 > thermal_zone41 thermal_zone49 thermal_zone56 thermal_zone63 > thermal_zone70 thermal_zone78 thermal_zone85 > cooling_device13 cooling_device20 cooling_device28 cooling_device7 > thermal_zone13 thermal_zone20 thermal_zone28 thermal_zone35 > thermal_zone42 thermal_zone5 thermal_zone57 thermal_zone64 > thermal_zone71 thermal_zone79 thermal_zone86 > cooling_device14 cooling_device21 cooling_device29 cooling_device8 > thermal_zone14 thermal_zone21 thermal_zone29 thermal_zone36 > thermal_zone43 thermal_zone50 thermal_zone58 thermal_zone65 > thermal_zone72 thermal_zone8 thermal_zone87 Nice, you have a crazy SoC here, good luck! :) > > But what userspace code needs to do this, and for what? > In Android, thermal daemon and thermal HAL as well as some init.rc > script would use those thermal paths for managing and monitoring > thermal. The daemon/HAL could have logic pipled in, however Android's > init.rc script would be really tricky. Then put that logic in your userspace code. > On a related note, we also create /dev/block/by-name links from userspace. Yes we do, from userspace, not from within the kernel itself, so I think you have answered the question :) thanks, greg k-h