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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 60FEDC32788 for ; Thu, 11 Oct 2018 16:01:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 17A8621470 for ; Thu, 11 Oct 2018 16:01:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="GkRE8ssr"; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="O/5B3kbt" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 17A8621470 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729076AbeJKX2s (ORCPT ); Thu, 11 Oct 2018 19:28:48 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:45522 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726036AbeJKX2r (ORCPT ); Thu, 11 Oct 2018 19:28:47 -0400 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id 6990260BFE; Thu, 11 Oct 2018 16:00:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1539273656; bh=t1Vo0NtjPsuSW/VmstdGm4/hznBdxfi6gzgBc4S20e4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=GkRE8ssrW7pq5CSRWDHHcDcTud/7KToHVf3WPB8XVlAfce30ZLnpSwEO32W4ffosM Kgtf5HaG5FenMSDzVcj/+ByE2TUWIEXe/8f0UmnrPpMvSAP14/SFgmKAT3w9aCV6B4 +hIju1tXa1T/8CdyVrm2htnzVgDSbL3pNEUOL148= Received: from localhost (i-global254.qualcomm.com [199.106.103.254]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: ilina@smtp.codeaurora.org) by smtp.codeaurora.org (Postfix) with ESMTPSA id 8037060BFE; Thu, 11 Oct 2018 16:00:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1539273654; bh=t1Vo0NtjPsuSW/VmstdGm4/hznBdxfi6gzgBc4S20e4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=O/5B3kbt9wRK++PEzZ/q+rtY3gSKZTAc2ngARRBi9Pqn2cPSbV1+TSeT9gyC8s/bi jMxZJ2Z4/h09nTNMj0GhHTUI9LMBJ6rRLb8JltG76aubilaO64V2rU0/Rz1i+Ag7FY wOKmyJODqkDwtTDHCFRnwdPnODO8xda03NWAFKW8= DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 8037060BFE Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=ilina@codeaurora.org Date: Thu, 11 Oct 2018 10:00:53 -0600 From: Lina Iyer To: Sudeep Holla Cc: "Raju P.L.S.S.S.N" , andy.gross@linaro.org, david.brown@linaro.org, rjw@rjwysocki.net, ulf.hansson@linaro.org, khilman@kernel.org, linux-arm-msm@vger.kernel.org, linux-soc@vger.kernel.org, rnayak@codeaurora.org, bjorn.andersson@linaro.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, devicetree@vger.kernel.org, sboyd@kernel.org, evgreen@chromium.org, dianders@chromium.org, mka@chromium.org, Lorenzo Pieralisi Subject: Re: [PATCH RFC v1 7/8] drivers: qcom: cpu_pd: Handle cpu hotplug in the domain Message-ID: <20181011160053.GA2371@codeaurora.org> References: <1539206455-29342-1-git-send-email-rplsssn@codeaurora.org> <1539206455-29342-8-git-send-email-rplsssn@codeaurora.org> <20181011112013.GC32752@e107155-lin> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20181011112013.GC32752@e107155-lin> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Sudeep, This is idea is based on GenPD/PM Domains, but solves for the CPU domain activities that need to be done from Linux when the CPU domain could be powered off. In that, it shares the same ideas from the series posted by Ulf. But this has no bearing on PSCI. The 845 SoC that Raju is working on, uses Platform-coordinated and so is largely deficient in meeting the power benefits achievable on this SoC, from Linux. If you have looked at the patches, you probably know by now, there are two things this patch does when the CPUs are powered off - - Flush RPMH requests to the controller (shared resource state requests after the CPU is powered off and resume to the current state before the CPU wakes up). - Setup the wakeup time for the CPUs in the hardware registers such that the hardware blocks are awake before a CPU is powered back on. This is like a back-off time for handling timer wakeups faster. The CPU PD does not power off the domain from Linux. That is done from PSCI firmware (ATF). These patches are doing the part that Linux has do, when powering off the CPUs, to achieve a low standby power consumption. On Thu, Oct 11 2018 at 05:20 -0600, Sudeep Holla wrote: >On Thu, Oct 11, 2018 at 02:50:54AM +0530, Raju P.L.S.S.S.N wrote: >> Use cpu hotplug callback mechanism to attach/dettach the cpu in >> the cpu power domain. During cpu hotplug callback registration, >> the starting callback is invoked on all online cpus. So there is >> no need to attach from device probe. >> > >To be more explicit, NACK to this series(patches 4-8 to be more specific) >unless you provide details on: > >1. Why this is not in PSCI implementation ? This is a linux activity and there is no provision in ATF or QC firmware to do this activity. The task of physically powering down the domain, still is a firmware decision and is done through PSCI platform coordinated in the firmware. >2. If PSCI is used on this platform, how does it work/co-exist ? Yes PSCI is used in this platform. ATF is the firmware and that supports only Platform Coordinated. This SoC uses cpuidle and the regular PSCI methods to power off the domain from the firmware. However, Linux has responsibilities that it needs to complete before the power down can be beneficial. >3. Is this a shortcut approached taken to bypass the CPU genpd attempts > from Lina/Ulf ? > This is an incorrect interpretation and an unwarranted accusation. There is no need to bypass CPU genpd attempts. That series stands on its own merits. (Thank you, Ulf). Raju has mentioned in the cover letter explicitly, that Ulf's patches posted here are for completeness of the concept, as that series is a dependency. But it will merged as part of Ulf's efforts. Isn't sharing ideas a key aspect of working with the community? This series just goes to say that the idea of CPU PM domains are useful, whether PSCI uses it or not. If you still need clarifications, Raju and I will be happy to set up a meeting and go over the idea. Thanks, Lina