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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,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 B99E6C433E0 for ; Wed, 24 Jun 2020 15:11:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8AAF620656 for ; Wed, 24 Jun 2020 15:11:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=samsung.com header.i=@samsung.com header.b="d3Kbk6je" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404266AbgFXPLi (ORCPT ); Wed, 24 Jun 2020 11:11:38 -0400 Received: from mailout2.w1.samsung.com ([210.118.77.12]:50817 "EHLO mailout2.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404243AbgFXPLh (ORCPT ); Wed, 24 Jun 2020 11:11:37 -0400 Received: from eucas1p2.samsung.com (unknown [182.198.249.207]) by mailout2.w1.samsung.com (KnoxPortal) with ESMTP id 20200624151135euoutp027a3e672795c5c0feb1d6f8b4ea00311d~bg4PeVFuX2325023250euoutp02L for ; Wed, 24 Jun 2020 15:11:35 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 mailout2.w1.samsung.com 20200624151135euoutp027a3e672795c5c0feb1d6f8b4ea00311d~bg4PeVFuX2325023250euoutp02L DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=samsung.com; s=mail20170921; t=1593011495; bh=vIfCBmSC+5GtsPYmRCTd8QesuVfaXVykkj6k7TxHWDA=; h=Subject:To:Cc:From:Date:In-Reply-To:References:From; b=d3Kbk6jeUH/b2U8aGb6xc4Ya2Uv1ARZ/vt/zcpb2yKnIdwyifNi/aogKF9wSFjcCY 0UfDxG+a4xfJBK1wYPPkNn1fpcJoTsVSCoacjsNacSk8Wvt/SunvyW8qmvUbe6HS+j yKx9sbNPfvw1rxIj4PokZL2Z4apGM1W75Z0Drnp0= Received: from eusmges1new.samsung.com (unknown [203.254.199.242]) by eucas1p1.samsung.com (KnoxPortal) with ESMTP id 20200624151135eucas1p1335bb5b1799513a14a8efb3d455078b2~bg4PLTJKl1469014690eucas1p1P; Wed, 24 Jun 2020 15:11:35 +0000 (GMT) Received: from eucas1p2.samsung.com ( [182.198.249.207]) by eusmges1new.samsung.com (EUCPMTA) with SMTP id BF.7B.06456.72D63FE5; Wed, 24 Jun 2020 16:11:35 +0100 (BST) Received: from eusmtrp1.samsung.com (unknown [182.198.249.138]) by eucas1p1.samsung.com (KnoxPortal) with ESMTPA id 20200624151134eucas1p1c70eef4c8ed9fd2fb0275cbec6576f44~bg4O0FaiQ1265612656eucas1p1Q; Wed, 24 Jun 2020 15:11:34 +0000 (GMT) Received: from eusmgms2.samsung.com (unknown [182.198.249.180]) by eusmtrp1.samsung.com (KnoxPortal) with ESMTP id 20200624151134eusmtrp1dfb6c70903341241eeeae3dbab271a31~bg4OzaZn01873818738eusmtrp1I; Wed, 24 Jun 2020 15:11:34 +0000 (GMT) X-AuditID: cbfec7f2-7efff70000001938-e6-5ef36d270ac2 Received: from eusmtip1.samsung.com ( [203.254.199.221]) by eusmgms2.samsung.com (EUCPMTA) with SMTP id D9.72.06017.62D63FE5; Wed, 24 Jun 2020 16:11:34 +0100 (BST) Received: from [106.210.123.115] (unknown [106.210.123.115]) by eusmtip1.samsung.com (KnoxPortal) with ESMTPA id 20200624151134eusmtip11cc243e141c704390f7521bb388feef3~bg4OEgzT22683126831eusmtip1N; Wed, 24 Jun 2020 15:11:33 +0000 (GMT) Subject: Re: brocken devfreq simple_ondemand for Odroid XU3/4? To: Lukasz Luba , Krzysztof Kozlowski , Willy Wolff Cc: Chanwoo Choi , MyungJoo Ham , Kyungmin Park , Kukjin Kim , linux-pm@vger.kernel.org, "linux-samsung-soc@vger.kernel.org" , linux-arm-kernel@lists.infradead.org, "linux-kernel@vger.kernel.org" From: Sylwester Nawrocki Message-ID: Date: Wed, 24 Jun 2020 17:11:33 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: <85f5a8c0-7d48-f2cd-3385-c56d662f2c88@arm.com> Content-Language: en-US Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrCKsWRmVeSWpSXmKPExsWy7djP87rquZ/jDPqv81hc//Kc1aL/8Wtm i/PnN7BbnG16w26x6fE1VovLu+awWXzuPcJoMeP8PiaLhU0t7Ba3G1ewWXw78YjRgdtjzbw1 jB47Z91l99i0qpPNY/OSeo++LasYPT5vkgtgi+KySUnNySxLLdK3S+DKOHj1OGvBbr6KtdfX sTYw3uPuYuTkkBAwkdjZ+5Kli5GLQ0hgBaPEufOv2CCcL4wS75uamSGcz4wSfzZ0ssK0NP9b DNWynFGiv+k6E4TzkVFi8afjTCBVwgJ2EvOv7QLrEBGolLg18zvYXGaBt0wSe/7eZgNJsAkY SvQe7WMEsXmBGm63dQI1c3CwCKhKzPymBBIWFYiV6Fu6gA2iRFDi5MwnLCA2p4C1xJJZb8F2 MQuIS9x6Mh/KlpfY/nYO2NkSArfYJb5fOQd1tovE6huNzBC2sMSr41vYIWwZidOTe1ggGpoZ JXp232aHcCYwStw/voARospa4s65X2wg1zELaEqs36UPEXaUeHvsDTNIWEKAT+LGW0GII/gk Jm2bDhXmlehoE4KoVpH4vWo6E4QtJdH95D/LBEalWUhem4XknVlI3pmFsHcBI8sqRvHU0uLc 9NRiw7zUcr3ixNzi0rx0veT83E2MwLR1+t/xTzsYv15KOsQowMGoxMO74cHHOCHWxLLiytxD jBIczEoivE5nT8cJ8aYkVlalFuXHF5XmpBYfYpTmYFES5zVe9DJWSCA9sSQ1OzW1ILUIJsvE wSnVwDhb0UHT0/UAK3/VOm3V7m+XtZsTomtu/szcWuNd5620QvC4628e+TRr1TLX1pslDCbX mexyjjtzCuo2LTpkeIth46zQKQ83CRkFZq9bzn0lau39+tvZSS2MTkbpy542X72iufcMc/8e +dNFbKd8en9N2HLHOW/366qaaR/qJ2yw6knJcZ38UImlOCPRUIu5qDgRAI2LKFhXAwAA X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFrrCIsWRmVeSWpSXmKPExsVy+t/xu7pquZ/jDN41m1hc//Kc1aL/8Wtm i/PnN7BbnG16w26x6fE1VovLu+awWXzuPcJoMeP8PiaLhU0t7Ba3G1ewWXw78YjRgdtjzbw1 jB47Z91l99i0qpPNY/OSeo++LasYPT5vkgtgi9KzKcovLUlVyMgvLrFVija0MNIztLTQMzKx 1DM0No+1MjJV0rezSUnNySxLLdK3S9DLOHj1OGvBbr6KtdfXsTYw3uPuYuTkkBAwkWj+t5il i5GLQ0hgKaPEm/5WIIcDKCElMb9FCaJGWOLPtS42EFtI4D2jxMzp7iC2sICdxPxru1hBbBGB Son7P+8wg8xhFnjPJPH3xEwmiKGrmSSOvVoJ1s0mYCjRe7SPEcTmBeq+3dbJBLKMRUBVYuY3 sGWiArES3+5tYYMoEZQ4OfMJC4jNKWAtsWTWWyYQm1lAXeLPvEvMELa4xK0n86Hi8hLb385h nsAoNAtJ+ywkLbOQtMxC0rKAkWUVo0hqaXFuem6xkV5xYm5xaV66XnJ+7iZGYIxuO/Zzyw7G rnfBhxgFOBiVeHg3PPgYJ8SaWFZcmXuIUYKDWUmE1+ns6Tgh3pTEyqrUovz4otKc1OJDjKZA v01klhJNzgemj7ySeENTQ3MLS0NzY3NjMwslcd4OgYMxQgLpiSWp2ampBalFMH1MHJxSDYzp 7T/VVRL5E0yePJPhEOwMUTx9xN9tRlaOpkfuKvfe6nk9xWdTMu4/WvYztTZm24Kfx5fbL1Ta F5F4Onf5hwtcU14WXl166ZFiyQxLVsnjLpdZNZZUMnTHfmc4eIHbXpnhf0Eow6RlDuZi9y34 Um4HpEy8X1MSpCfxp8xPiWdeWtSMu6tfvVFiKc5INNRiLipOBACBoft/5wIAAA== X-CMS-MailID: 20200624151134eucas1p1c70eef4c8ed9fd2fb0275cbec6576f44 X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-RootMTR: 20200624103308eucas1p188a5fe3cee1916d9430c9971c2dab3a3 X-EPHeader: CA CMS-TYPE: 201P X-CMS-RootMailID: 20200624103308eucas1p188a5fe3cee1916d9430c9971c2dab3a3 References: <20200623164733.qbhua7b6cg2umafj@macmini.local> <20200623191129.GA4171@kozik-lap> <85f5a8c0-7d48-f2cd-3385-c56d662f2c88@arm.com> Sender: linux-samsung-soc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-samsung-soc@vger.kernel.org Hi All, On 24.06.2020 12:32, Lukasz Luba wrote: > I had issues with devfreq governor which wasn't called by devfreq > workqueue. The old DELAYED vs DEFERRED work discussions and my patches > for it [1]. If the CPU which scheduled the next work went idle, the > devfreq workqueue will not be kicked and devfreq governor won't check > DMC status and will not decide to decrease the frequency based on low > busy_time. > The same applies for going up with the frequency. They both are > done by the governor but the workqueue must be scheduled periodically. As I have been working on resolving the video mixer IOMMU fault issue described here: https://patchwork.kernel.org/patch/10861757 I did some investigation of the devfreq operation, mostly on Odroid U3. My conclusions are similar to what Lukasz says above. I would like to add that broken scheduling of the performance counters read and the devfreq updates seems to have one more serious implication. In each call, which normally should happen periodically with fixed interval we stop the counters, read counter values and start the counters again. But if period between calls becomes long enough to let any of the counters overflow, we will get wrong performance measurement results. My observations are that the workqueue job can be suspended for several seconds and conditions for the counter overflow occur sooner or later, depending among others on the CPUs load. Wrong bus load measurement can lead to setting too low interconnect bus clock frequency and then bad things happen in peripheral devices. I agree the workqueue issue needs to be fixed. I have some WIP code to use the performance counters overflow interrupts instead of SW polling and with that the interconnect bus clock control seems to work much better. -- Regards, Sylwester