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,URIBL_BLOCKED,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 7AC76C433DF for ; Wed, 17 Jun 2020 10:40:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 610E42082F for ; Wed, 17 Jun 2020 10:40:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725894AbgFQKks (ORCPT ); Wed, 17 Jun 2020 06:40:48 -0400 Received: from foss.arm.com ([217.140.110.172]:55276 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725860AbgFQKkr (ORCPT ); Wed, 17 Jun 2020 06:40:47 -0400 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 EC958C0A; Wed, 17 Jun 2020 03:40:46 -0700 (PDT) Received: from [10.37.12.67] (unknown [10.37.12.67]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D9D923F71F; Wed, 17 Jun 2020 03:40:44 -0700 (PDT) Subject: Re: [PATCH 0/4] Restore big.LITTLE cpuidle driver for Exynos To: Marek Szyprowski , Anand Moon Cc: Linux PM list , linux-arm-kernel , linux-samsung-soc@vger.kernel.org, Lorenzo Pieralisi , Bartlomiej Zolnierkiewicz , Daniel Lezcano , Krzysztof Kozlowski References: <20200616081230.31198-1-m.szyprowski@samsung.com> <3e6b5dbb-a8a2-e3db-d740-53e13676455c@samsung.com> From: Lukasz Luba Message-ID: <6b2ac503-62e1-35a6-6dc7-232597367396@arm.com> Date: Wed, 17 Jun 2020 11:40:42 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <3e6b5dbb-a8a2-e3db-d740-53e13676455c@samsung.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-samsung-soc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-samsung-soc@vger.kernel.org On 6/17/20 10:48 AM, Marek Szyprowski wrote: > Hi Anand, > > On 16.06.2020 22:58, Anand Moon wrote: >> On Tue, 16 Jun 2020 at 13:44, Marek Szyprowski wrote: >>> The ARM big.LITTLE cpuidle driver has been enabled and tested on Samsung >>> Exynos 5420/5800 based Peach Pit/Pi Chromebooks and in fact it worked >>> only on those boards. >>> >>> However, support for it was broken by the commit 833b5794e330 ("ARM: >>> EXYNOS: reset Little cores when cpu is up") and then never enabled in the >>> exynos_defconfig. This patchset provides the needed fix to the common >>> code and restores support for it. Thanks to Lukasz Luba who motivated me >>> to take a look into this issue. >>> >> Thanks for this updates. >> >> But I feel some DTS changes are missing for example >> d2e5c871ed8a drivers: cpuidle: initialize big.LITTLE driver through DT > > This is not strictly needed. The bl-cpuidle matches also to the A7/A15 > CPU product ids and it is properly instantiated on the Peach Pit/Pi > Chromebooks. Those CPU DT properties were added as a future-proof > generic solution. I won't hurt to add them though. > >> But I feel that this feature is not working as desired since >> still some missing code changes for cluster idle states are missing. >> like clock PWR_CTR and PWR_CTRL2. > > I cannot judge now. All I can test now is a that the boards enters those > idle states and system works stable. I cannot measure power consumption, > because currently I have only remote access to the boards. I agree with Marek. This can be done incrementally. The series fixes the code path which was working. After the investigation with a power meter, a proper set of new patches might come if needed. As a hint to measure this power consumption difference, because it might be tricky, I would suggest to heat up the SoC. The main difference between wfi and deeper idle which cut the power to some components (like caches) should be seen at higher voltage OPP and higher temperature. It's due to the fact that static power (leakage) is related to Vdd and temperature - higher voltage -> higher leakage higher temp -> higher leakage This difference (idle state 0 vs 1) should be amplified in the above scenario and easier to measure. I am going to review this series after finishing hotplug tests. Regards, Lukasz