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=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 0DFDAC83000 for ; Wed, 29 Apr 2020 15:50:28 +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 C957A20B80 for ; Wed, 29 Apr 2020 15:50:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="BhdWhz8F" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C957A20B80 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=rjwysocki.net Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Date:Subject:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=sFYsRY6YD6woQo1c+C+Pci58IrafDMLUtxIThpsQpN0=; b=BhdWhz8F/rcBKK ar414xdqUCoZZbuNSC/un9csqhHj8bENTbQ8/dgmRVPcPA5LlaIVpdvkaSem95JqtSWyAIryb7+qf yIWHiRw5DaiVkbPUewaz1MLigwOIdaX1hRhkGvHYkIUAaImG2cJ60pbFiMHFf9lpMdqLLTSogg8vo eQLSMPWIWMQjdVOjrX3B5bhVhKmyqCs/dbiUtuJoke1qlH8RaQuyYtDJ5AjElcbGrycJFRR/HTod4 PEWf47q83kIYhKS36jXKFvjrfSEbelc83JdBRRilgabaFLZ5dsAZ/lApo+mhUjmWxHD3ZzQFFfDPe eGwEArI+LL59ZsCnVcNw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jToyU-0000Bj-Cs; Wed, 29 Apr 2020 15:50:14 +0000 Received: from cloudserver094114.home.pl ([79.96.170.134]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jToyQ-00077L-MB for linux-arm-kernel@lists.infradead.org; Wed, 29 Apr 2020 15:50:12 +0000 Received: from 185.80.35.16 (185.80.35.16) (HELO kreacher.localnet) by serwer1319399.home.pl (79.96.170.134) with SMTP (IdeaSmtpServer 0.83.415) id bb23fa4412e3993e; Wed, 29 Apr 2020 17:50:04 +0200 From: "Rafael J. Wysocki" To: Benjamin Gaignard Subject: Re: [RFC 0/3] Introduce cpufreq minimum load QoS Date: Wed, 29 Apr 2020 17:50:04 +0200 Message-ID: <7657495.QyJl4BcWH5@kreacher> In-Reply-To: <20200424114058.21199-1-benjamin.gaignard@st.com> References: <20200424114058.21199-1-benjamin.gaignard@st.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200429_085010_937732_B8D79B29 X-CRM114-Status: UNSURE ( 8.84 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mcoquelin.stm32@gmail.com, alexandre.torgue@st.com, len.brown@intel.com, viresh.kumar@linaro.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, Patrick Bellasi , pavel@ucw.cz, hugues.fruchet@st.com, mchehab@kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Friday, April 24, 2020 1:40:55 PM CEST Benjamin Gaignard wrote: > When start streaming from the sensor the CPU load could remain very low > because almost all the capture pipeline is done in hardware (i.e. without > using the CPU) and let believe to cpufreq governor that it could use lower > frequencies. If the governor decides to use a too low frequency that > becomes a problem when we need to acknowledge the interrupt during the > blanking time. > The delay to ack the interrupt and perform all the other actions before > the next frame is very short and doesn't allow to the cpufreq governor to > provide the required burst of power. That led to drop the half of the frames. > > To avoid this problem, DCMI driver informs the cpufreq governors by adding > a cpufreq minimum load QoS resquest. This seems to be addressing a use case that can be addressed with the help of utilization clamps with less power overhead. Thanks! _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel