From patchwork Fri Apr 24 11:40:55 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Benjamin GAIGNARD X-Patchwork-Id: 11507695 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 9F18A14B4 for ; Fri, 24 Apr 2020 11:41:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 87B19215A4 for ; Fri, 24 Apr 2020 11:41:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=st.com header.i=@st.com header.b="Es8C1862" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726717AbgDXLlc (ORCPT ); Fri, 24 Apr 2020 07:41:32 -0400 Received: from mx08-00178001.pphosted.com ([91.207.212.93]:14872 "EHLO mx07-00178001.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726849AbgDXLlW (ORCPT ); Fri, 24 Apr 2020 07:41:22 -0400 Received: from pps.filterd (m0046660.ppops.net [127.0.0.1]) by mx07-00178001.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 03OBWhDp023182; Fri, 24 Apr 2020 13:41:05 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=st.com; h=from : to : cc : subject : date : message-id : mime-version : content-type; s=STMicroelectronics; bh=48ijLv0H8aPna6VpnvuqVOGM5Dz2rM04kkZgD9MA9eE=; b=Es8C1862D8FqWo05sEOjdJfrZx2FT/J+PwwAg+M0K/cS4OlJmwyTpgq9bfrxqVlgXYbJ nbWRakh3o8x4jlwSeS4fVYqVs2VlcsBK7F3Mq1cX8TTF5AW8AQa+kosfClU56KGad1l/ 0OO1kRPI8GP5ap1G+lKH6UIhRPtSZ+BUb6L1nQU6ooLF8yVVZcLf6qetCgjmesTMtzh/ rhyTj9i0zGv0p9dvY7D7PacBj0BDhyxRaNhrSQU5teiMSf15EkxwCrm4F3CORLnCnkiL fin6EzodcbFKmO5Lo4pHiV4uc0GTZmd6qU0bBVIGhvvdWD4X1gjbCPoG9Cco0G9oTbA1 1g== Received: from beta.dmz-eu.st.com (beta.dmz-eu.st.com [164.129.1.35]) by mx07-00178001.pphosted.com with ESMTP id 30fpp9bchc-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 24 Apr 2020 13:41:05 +0200 Received: from euls16034.sgp.st.com (euls16034.sgp.st.com [10.75.44.20]) by beta.dmz-eu.st.com (STMicroelectronics) with ESMTP id 25802100034; Fri, 24 Apr 2020 13:41:02 +0200 (CEST) Received: from Webmail-eu.st.com (sfhdag3node3.st.com [10.75.127.9]) by euls16034.sgp.st.com (STMicroelectronics) with ESMTP id 1156C2B3DA0; Fri, 24 Apr 2020 13:41:02 +0200 (CEST) Received: from localhost (10.75.127.49) by SFHDAG3NODE3.st.com (10.75.127.9) with Microsoft SMTP Server (TLS) id 15.0.1347.2; Fri, 24 Apr 2020 13:41:01 +0200 From: Benjamin Gaignard To: , , , , , , , CC: , , , , , Benjamin Gaignard Subject: [RFC 0/3] Introduce cpufreq minimum load QoS Date: Fri, 24 Apr 2020 13:40:55 +0200 Message-ID: <20200424114058.21199-1-benjamin.gaignard@st.com> X-Mailer: git-send-email 2.15.0 MIME-Version: 1.0 X-Originating-IP: [10.75.127.49] X-ClientProxiedBy: SFHDAG3NODE2.st.com (10.75.127.8) To SFHDAG3NODE3.st.com (10.75.127.9) X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138,18.0.676 definitions=2020-04-24_04:2020-04-23,2020-04-24 signatures=0 Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org 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. Benjamin Gaignard (3): PM: QoS: Introduce cpufreq minimum load QoS cpufreq: governor: Use minimum load QoS media: stm32-dcmi: Inform cpufreq governors about cpu load needs drivers/cpufreq/cpufreq_governor.c | 5 + drivers/media/platform/stm32/stm32-dcmi.c | 8 ++ include/linux/pm_qos.h | 12 ++ kernel/power/qos.c | 213 ++++++++++++++++++++++++++++++ 4 files changed, 238 insertions(+)