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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 D4F56C2D0D2 for ; Fri, 20 Dec 2019 12:01:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B465424679 for ; Fri, 20 Dec 2019 12:01:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727258AbfLTMBU (ORCPT ); Fri, 20 Dec 2019 07:01:20 -0500 Received: from foss.arm.com ([217.140.110.172]:50032 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727184AbfLTMBT (ORCPT ); Fri, 20 Dec 2019 07:01:19 -0500 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 6006530E; Fri, 20 Dec 2019 04:01:19 -0800 (PST) Received: from bogus (e107155-lin.cambridge.arm.com [10.1.196.42]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 613AB3F719; Fri, 20 Dec 2019 04:01:17 -0800 (PST) Date: Fri, 20 Dec 2019 12:01:12 +0000 From: Sudeep Holla To: Ulf Hansson Cc: Lorenzo Pieralisi , Rob Herring , Linux PM , "Rafael J . Wysocki" , Daniel Lezcano , Mark Rutland , Lina Iyer , Vincent Guittot , Stephen Boyd , Andy Gross , Bjorn Andersson , Kevin Hilman , Sudeep Holla , Linux ARM , linux-arm-msm Subject: Re: [PATCH v4 13/14] cpuidle: psci: Add support for PM domains by using genpd Message-ID: <20191220120112.GA26547@bogus> References: <20191211154343.29765-1-ulf.hansson@linaro.org> <20191211154343.29765-14-ulf.hansson@linaro.org> <20191219143427.GF20746@bogus> <20191219180629.GC21846@bogus> <20191220100745.GB6731@bogus> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org On Fri, Dec 20, 2019 at 12:27:39PM +0100, Ulf Hansson wrote: > On Fri, 20 Dec 2019 at 11:07, Sudeep Holla wrote: [...] > > > > Even if you don't create all these genpd domains, it is still degraded > > mode and we are anyway not changing that. Let me know if my understanding > > is wrong here. > > Your understanding is wrong. > > If I remove the genpds because psci_set_osi_mode() fails, then in the > current suggested initialization path, that will lead to that the > entire cpuidle-psci driver will fail to initiate (which is because > psci_dt_attach_cpu() returns an error). In other words, only WFI state > will be used by cpuidle as there will be no cpuidle driver registered > at all. > > That would not be an acceptable behaviour, as it would make the > situation worse than today. > > What we want in this scenario is to keep using all the idle states for > the CPUs, but ignores those for the cluster. That we both agree on, > right? > Yes, I agree and understand that. I was assuming as part of this change you will fixup psci_dt_cpu_init_idle not to return error but just allow CPU level idle. Sorry if that was not clear, I was always assuming that. > > > > I am sure, DTB may get copied to different platform and the firmware may > > not support OSI. I know we have logs, but creating and leaving those > > genpd domains unused will be just confusing. Please change that. > > We are not creating any genpds unless OSI mode is supported. We do not > even try to attach CPUs to the PM domains, unless OSI mode is > supported. So this should already work according to your expectations > and previous requests. > Yes I understand, but checking if "OSI mode is supported" is not same as "setting OSI mode". Until OSI mode is set, it is default/PC mode, so we need to work based on that assumption. > To address your concern about removing genpds when psci_set_osi_mode() > fails, we also need to address the problems we get when calling > psci_dt_attach_cpu(). There are two viable options as I see it. > Shouldn't that fail ? Sorry, I might be missing something. > 1. Prevent calling psci_dt_attach_cpu() altogether when > psci_set_osi_mode() failed. This means another function needs to be > shared from cpuidle-psci-domain.c to let cpuidle-psci.c know about it. > If we don't create any genpd, will psci_dt_attach_cpu fail ? > 2. We can let psci_dt_attach_cpu() return NULL, when > psci_set_osi_mode() failed - as this information is already known by > cpuidle-psci-domain.c. > Yes I was making all the arguments/discussion based on that. Do you see any issues with that ? Any races possible ? > I vote for option 2, but what do you think? > Me too from the time I started the discussion, I assume a lot and don't put this into words in the email. -- Regards, Sudeep