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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 42A14C3F2CD for ; Wed, 4 Mar 2020 12:23:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1E56F2146E for ; Wed, 4 Mar 2020 12:23:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387801AbgCDMXQ (ORCPT ); Wed, 4 Mar 2020 07:23:16 -0500 Received: from foss.arm.com ([217.140.110.172]:33616 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387776AbgCDMXQ (ORCPT ); Wed, 4 Mar 2020 07:23:16 -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 C4C6331B; Wed, 4 Mar 2020 04:23:15 -0800 (PST) Received: from bogus (e103737-lin.cambridge.arm.com [10.1.197.49]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 3B76E3F534; Wed, 4 Mar 2020 04:23:14 -0800 (PST) Date: Wed, 4 Mar 2020 12:23:12 +0000 From: Sudeep Holla To: Ulf Hansson Cc: Lorenzo Pieralisi , linux-pm@vger.kernel.org, "Rafael J . Wysocki" , Daniel Lezcano , Lina Iyer , Vincent Guittot , Stephen Boyd , Bjorn Andersson , Benjamin Gaignard , Sudeep Holla , linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v2 4/4] cpuidle: psci: Allow WFI to be the only state for the hierarchical topology Message-ID: <20200304122312.GE25004@bogus> References: <20200303203559.23995-1-ulf.hansson@linaro.org> <20200303203559.23995-5-ulf.hansson@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200303203559.23995-5-ulf.hansson@linaro.org> 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 The $subject is bit confusing. IIUC, if there are no idle states to manage including hierarchical domain states you will not register the driver right ? If so, you are not allowing WFI to be the only state, hence my concern with $subject. On Tue, Mar 03, 2020 at 09:35:59PM +0100, Ulf Hansson wrote: > It's possible that only the WFI state is supported for the CPU, while also > a shared idle state exists for a group of CPUs. > > When the hierarchical topology is used, the shared idle state may not be > compatible with arm,idle-state, rather with "domain-idle-state", which > makes dt_init_idle_driver() to return zero. This leads to that the > cpuidle-psci driver bails out during initialization, avoiding to register a > cpuidle driver and instead relies on the default architectural back-end > (called via cpu_do_idle()). In other words, the shared idle state becomes > unused. > > Let's fix this behaviour, by allowing the dt_init_idle_driver() to return 0 > and then continue with the initialization. If it turns out that the > hierarchical topology is used and we have some additional states to manage, > then continue with the cpuidle driver registration, otherwise bail out as > before. > > Reported-by: Benjamin Gaignard > Fixes: a65a397f2451 ("cpuidle: psci: Add support for PM domains by using genpd") > Signed-off-by: Ulf Hansson > --- > > Changes in v2: > - Convert the error code returned from psci_cpu_suspend_enter() into an > expected error code by cpuidle core. > > --- > drivers/cpuidle/cpuidle-psci.c | 48 +++++++++++++++++++++------------- > 1 file changed, 30 insertions(+), 18 deletions(-) > > diff --git a/drivers/cpuidle/cpuidle-psci.c b/drivers/cpuidle/cpuidle-psci.c > index bae9140a65a5..ae0fabec2742 100644 > --- a/drivers/cpuidle/cpuidle-psci.c > +++ b/drivers/cpuidle/cpuidle-psci.c > @@ -56,16 +56,19 @@ static int psci_enter_domain_idle_state(struct cpuidle_device *dev, > u32 *states = data->psci_states; > struct device *pd_dev = data->dev; > u32 state; > - int ret; > + int ret = 0; > > /* Do runtime PM to manage a hierarchical CPU toplogy. */ > pm_runtime_put_sync_suspend(pd_dev); > > state = psci_get_domain_state(); > - if (!state) > + if (!state && states) > state = states[idx]; > > - ret = psci_enter_state(idx, state); > + if (state) > + ret = psci_cpu_suspend_enter(state) ? -1 : idx; > + else > + cpu_do_idle(); May be, I haven't followed this completely yet, but I don't want to be in the position to replicated default arch idle hook. Just use the one that exist by simply not registering the driver. -- Regards, Sudeep