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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 19CB5C00A8F for ; Tue, 24 Oct 2023 12:03:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233434AbjJXMDc (ORCPT ); Tue, 24 Oct 2023 08:03:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34618 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232469AbjJXMDc (ORCPT ); Tue, 24 Oct 2023 08:03:32 -0400 Received: from mx.kernkonzept.com (serv1.kernkonzept.com [IPv6:2a01:4f8:1c1c:b490::2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 352D3F9; Tue, 24 Oct 2023 05:03:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=kernkonzept.com; s=mx1; h=In-Reply-To:Content-Type:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Content-Transfer-Encoding:Reply-To: Content-ID:Content-Description; bh=zRIi9/LubZwPopqf6kr3BLpCYi15YnR3163PaROLkPc=; b=mTYVwfkdKLTHhanJB6iXTcGdRN B4MGvwjKxtEHB9ISxJYLjUPkavsTwTRNUl+/dYaX8yIOwuQxB7l9Np7qR13iLSaKKHdBO0cJGkzd1 z6+PwxU6TURDYTmHgLz9xsIBJxXlfBQgwSXCjAnQCaj8RjJi041unbBCCgvcs1T7TkzE9Wz6bzxHq 5A9yH8mOT1hmHimnZy+WkCoU6cMmRgZ7sQtnjBzlPfMGk/4pXLyTnc+pcMVGqBAVPL2M/8TqlOFup z99GPSxcLYXAtUlrlJtsa3F9kVjgZilmYOJEo5yezpZXCs/tExSS3HRS4iPEy1l70zpPHHtUetTZu SMl1I8Mg==; Received: from [10.22.3.24] (helo=kernkonzept.com) by mx.kernkonzept.com with esmtpsa (TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.96) id 1qvG83-000jUo-0O; Tue, 24 Oct 2023 14:03:22 +0200 Date: Tue, 24 Oct 2023 14:03:17 +0200 From: Stephan Gerhold To: Ulf Hansson Cc: Viresh Kumar , Andy Gross , Bjorn Andersson , Konrad Dybcio , Ilia Lin , "Rafael J. Wysocki" , Rob Herring , Krzysztof Kozlowski , Conor Dooley , linux-pm@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, Stephan Gerhold , stable@vger.kernel.org Subject: Re: [PATCH v2 2/3] cpufreq: qcom-nvmem: Enable virtual power domain devices Message-ID: References: <20231018-msm8909-cpufreq-v2-0-0962df95f654@kernkonzept.com> <20231018-msm8909-cpufreq-v2-2-0962df95f654@kernkonzept.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On Thu, Oct 19, 2023 at 01:26:19PM +0200, Ulf Hansson wrote: > On Thu, 19 Oct 2023 at 12:24, Ulf Hansson wrote: > > > > On Wed, 18 Oct 2023 at 10:06, Stephan Gerhold > > wrote: > > > > > > The genpd core caches performance state votes from devices that are > > > runtime suspended as of commit 3c5a272202c2 ("PM: domains: Improve > > > runtime PM performance state handling"). They get applied once the > > > device becomes active again. > > > > > > To attach the power domains needed by qcom-cpufreq-nvmem the OPP core > > > calls genpd_dev_pm_attach_by_id(). This results in "virtual" dummy > > > devices that use runtime PM only to control the enable and performance > > > state for the attached power domain. > > > > > > However, at the moment nothing ever resumes the virtual devices created > > > for qcom-cpufreq-nvmem. They remain permanently runtime suspended. This > > > means that performance state votes made during cpufreq scaling get > > > always cached and never applied to the hardware. > > > > > > Fix this by enabling the devices after attaching them and use > > > dev_pm_syscore_device() to ensure the power domains also stay on when > > > going to suspend. Since it supplies the CPU we can never turn it off > > > from Linux. There are other mechanisms to turn it off when needed, > > > usually in the RPM firmware (RPMPD) or the cpuidle path (CPR genpd). > > > > I believe we discussed using dev_pm_syscore_device() for the previous > > version. It's not intended to be used for things like the above. > > > > Moreover, I was under the impression that it wasn't really needed. In > > fact, I would think that this actually breaks things for system > > suspend/resume, as in this case the cpr driver's genpd > > ->power_on|off() callbacks are no longer getting called due this, > > which means that the cpr state machine isn't going to be restored > > properly. Or did I get this wrong? > > BTW, if you really need something like the above, the proper way to do > it would instead be to call device_set_awake_path() for the device. > Unfortunately this does not work correctly. When I use device_set_awake_path() it does set dev->power.wakeup_path = true. However, this flag is cleared again in device_prepare() when entering suspend. To me it looks a bit like wakeup_path is not supposed to be set directly by drivers? Before and after your commit 8512220c5782 ("PM / core: Assign the wakeup_path status flag in __device_prepare()") it seems to be internally bound to device_may_wakeup(). It works if I make device_may_wakeup() return true, with device_set_wakeup_capable(dev, true); device_wakeup_enable(dev); but that also allows *disabling* the wakeup from sysfs which doesn't really make sense for the CPU. Any ideas? Thanks! -- Stephan Gerhold Kernkonzept GmbH at Dresden, Germany, HRB 31129, CEO Dr.-Ing. Michael Hohmuth