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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0524DC433EF for ; Fri, 22 Oct 2021 12:04:56 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B9F5A610EA for ; Fri, 22 Oct 2021 12:04:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org B9F5A610EA Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:Cc:To:Subject:Message-ID:Date:From: In-Reply-To:References:MIME-Version:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=ny7POaCoFj9O9HapQGYkUHrecngEBP/2feWdr2lhVfw=; b=2uGUSV07vOh7W6 AIgKfIi4YY5/utJmm4DcVUoXlje7JnBsItkDA9nVVSjx2/pq3ZMCcOU9dsXRHMgbaB8CtsSDdaSmC 8HgSQaXSyGC3g34/YTPqSq3kbFCnzf2ZNWkPhdshipXV8QWbavNlS8XL8GrJlwzGTAr2ikGpTDPyl 1Mpijenp2kehXj0dnNhkyc8956hG+vtzNOPf6hlRH7Ins7rPtVTJL77F5ipmP6fWjlOz5RQpXn4kO raOJRHDKzYG3qsgOtfSa+I8T2rStfOpS4pQ5uhlndDiwUOWcpXzO2W+1r3x+3rgXbGA9SgFgNU5ID 7CgFpApfqz1eT3uDpLvg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mdtGV-00Aka2-0s; Fri, 22 Oct 2021 12:03:15 +0000 Received: from mail-oo1-f54.google.com ([209.85.161.54]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mdtG3-00AkRc-HQ for linux-arm-kernel@lists.infradead.org; Fri, 22 Oct 2021 12:02:49 +0000 Received: by mail-oo1-f54.google.com with SMTP id n15-20020a4ad12f000000b002b6e3e5fd5dso1038431oor.1 for ; Fri, 22 Oct 2021 05:02:43 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=vb9ybLLtVGcasBUj4S63VDy6H8luqutt3xdc3pcVq78=; b=j86s+l18C0t/CXOTYK9MzwvONs7DXxt58Fwok5390GlZZZYde/gyoEqfd4aySquVK1 aKs3L1gq6tO8YDds37HF+bAhnu9Uo7k36SEA2hr4mCwWLgXhfQDw+OEfDYrBBXymqbkQ rVtXK0/aBFmP4ZuGU1puc4HacwAllXiMAeHRp58WZb6ZQalXsdWSyWgm9BpR/JNwZlt6 9bWN0NHK3nWlIUi9zg06CAqCOj8zB/fQ5QfsUmfm2ra3hbcSIN7ghHG6ufIvUI+Agur/ q060lcYf0+G0J5Q1NWArLPAwkh7G+nsdsFH15CR71zK63y8MPP9D4GyshPZLPCed8EcE XdwQ== X-Gm-Message-State: AOAM533esCZqwbglf12iAOlfNPig49BH6fooOXJkpqCVTQOAHoSpkwuV CXvK6PB1IbCGtiV6D0om6PBhxTkmso5ono+0+5Q= X-Google-Smtp-Source: ABdhPJze3v0ez3rcx7Cqcn8ZP7TMyRJHdxJ29JvtpjDpetrBwYdcs+dtB5hGPVCMULTmj42hLs19IAd80/Pt97/FMZg= X-Received: by 2002:a05:6820:54e:: with SMTP id n14mr8926037ooj.89.1634904163022; Fri, 22 Oct 2021 05:02:43 -0700 (PDT) MIME-Version: 1.0 References: <20210929144451.113334-1-ulf.hansson@linaro.org> <20210929144451.113334-3-ulf.hansson@linaro.org> In-Reply-To: From: "Rafael J. Wysocki" Date: Fri, 22 Oct 2021 14:02:26 +0200 Message-ID: Subject: Re: [PATCH 2/2] PM: sleep: Fix runtime PM based cpuidle support To: Ulf Hansson Cc: "Rafael J. Wysocki" , Daniel Lezcano , Linux PM , Maulik Shah , Peter Zijlstra , Vincent Guittot , Len Brown , Bjorn Andersson , Linux ARM , Linux Kernel Mailing List X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211022_050247_647266_D0444568 X-CRM114-Status: GOOD ( 36.74 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Oct 22, 2021 at 12:18 PM Ulf Hansson wrote: > > On Thu, 21 Oct 2021 at 21:56, Ulf Hansson wrote: > > > > On Thu, 21 Oct 2021 at 21:02, Rafael J. Wysocki wrote: > > > > > > On Thu, Oct 21, 2021 at 8:12 PM Ulf Hansson wrote: > > > > > > > > On Thu, 21 Oct 2021 at 18:33, Rafael J. Wysocki wrote: > > > > > > > > > > On Thu, Oct 21, 2021 at 6:17 PM Ulf Hansson wrote: > > > > > > [cut] > > > > > > > > So in theory you could check the pm_runtime_put_sync_suspend() return > > > > > value and fall back to something like WFI if that's an error code. > > > > > > > > I have already tried that, but it simply got too complicated. The main > > > > issue was that runtime PM could become disabled for the device in the > > > > middle of executing the ->enter() callback. > > > > > > So IIUC the problem is that you cannot resume after suspending in that case. > > > > > > IOW, you need to guarantee that if the suspend is successful, the > > > resume also will take place, but if the suspend fails, you basically > > > don't care. > > > > Exactly. > > > > > > > > > For example, if pm_runtime_get_sync() fails, I still need to make sure > > > > the reference counting in genpd becomes correct - and I can't do that > > > > using dev_pm_genpd_resume(). That's because it's not designed to be > > > > called in this "unknown" suspend phase, but should be called after the > > > > noirq phase and be properly balanced with dev_pm_genpd_suspend(). > > > > > > > > In other words, the error path didn't work out for me. > > > > > > It should be sufficient to call wake_up_all_idle_cpus() in the suspend > > > path before dpm_suspend_late(), because system suspend acquires a > > > PM-runtime reference on every device. IOW, it won't let any devices > > > runtime-suspend, so if your power domain devices are resumed in that > > > path, they will never suspend again in it and the > > > pm_runtime_put_sync_suspend() in __psci_enter_domain_idle_state() > > > becomes a reference counter management call which works regardless of > > > whether or not PM runtime is disabled. > > > > That sounds like a great idea, this should work too! Then the question > > is, how to make that call to wake_up_all_idle_cpus() to become > > optional - or only invoked for the cpuidle drivers that need it. It need not be optional. For suspend-to-idle it doesn't matter, because all CPUs will be woken up from idle shortly anyway. For other suspend variants this doesn't matter, because all secondary CPUs will be taken offline shortly and the primary CPU will call into the platform "sleep" handler. > > > > In any case, I will try this out, thanks for the suggestion! > > I now recall that I have already tried this, but unfortunately it doesn't work. > > The problem is that the dev->power.syscore flag is set for the device, > which makes device_prepare() to bail out early and skip calling > pm_runtime_get_noresume(). This needs to be fixed, then. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel