From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Osipenko Subject: Re: [RFC PATCH v6 6/9] media: tegra: Add Tegra210 Video input driver Date: Wed, 8 Apr 2020 01:14:05 +0300 Message-ID: References: <1585963507-12610-1-git-send-email-skomatineni@nvidia.com> <1585963507-12610-7-git-send-email-skomatineni@nvidia.com> <200bb96e-2d07-764f-9e14-55538dc742fd@gmail.com> <23bfab09-b464-6e51-9843-06d13000e9b9@nvidia.com> <08cd31d5-e8b9-4d3a-fb0e-0e4462947d96@nvidia.com> <12a834ac-52b1-6dc0-7d3a-3e6a1fa85a2a@gmail.com> <760d071e-0cbc-b3eb-9231-fb9f9ecb44a6@nvidia.com> <9e317f65-8a02-3b15-cfec-8e0d8374130e@gmail.com> <97b35910-4c93-123a-43a0-eb14476ed0f3@nvidia.com> <84ad4e2d-6ac1-e1f4-1c55-5edaae850631@nvidia.com> <15a879b3-8fb9-6821-3cdc-104ba583ac12@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <15a879b3-8fb9-6821-3cdc-104ba583ac12-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> Content-Language: en-US Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Sowjanya Komatineni , thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, jonathanh-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org, frankc-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org, hverkuil-qWit8jRvyhVmR6Xm/wNWPw@public.gmane.org, sakari.ailus-X3B1VOXEql0@public.gmane.org, helen.koike-ZGY8ohtN/8qB+jHODAdFcQ@public.gmane.org Cc: sboyd-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, linux-media-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-clk-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-tegra@vger.kernel.org 08.04.2020 01:08, Dmitry Osipenko пишет: > 08.04.2020 00:08, Sowjanya Komatineni пишет: > ... >>>> I think you need a semaphore with resource count = 2. >>> we hold on to issuing capture if more than 2 buffers are queued and it >>> continues only after fifo has min 1 slot empty >> >> >> Just want to close on this part of feedback. Hope above explanation is >> clear regarding triggering/issuing at max 2 frame capture to VI HW and >> also regarding capture threads where they use wait_event_interruptible >> to prevent blocking waiting for buffers to be available for captures. >> >> So no changes related to this part are needed in v7. > From what I see in the code, you "hold on" by making kthread to spin in > a busy-loop while caps_inflight >= SYNCPT_FIFO_DEPTH. So some change > should be needed to prevent this. Looks like some other media drivers do: schedule_timeout_uninterruptible(1); to avoid CPU hogging when contention is detected. 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_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, 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 65823C2BB1D for ; Tue, 7 Apr 2020 22:14:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 407FA2083E for ; Tue, 7 Apr 2020 22:14:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="rAbkst+f" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726571AbgDGWOK (ORCPT ); Tue, 7 Apr 2020 18:14:10 -0400 Received: from mail-lf1-f65.google.com ([209.85.167.65]:36116 "EHLO mail-lf1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726380AbgDGWOK (ORCPT ); Tue, 7 Apr 2020 18:14:10 -0400 Received: by mail-lf1-f65.google.com with SMTP id w145so3627481lff.3; Tue, 07 Apr 2020 15:14:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:from:to:cc:references:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=6uRUHjT3H2vueqpdrwwP13xe2CMDcv0WafFpeyYI7lU=; b=rAbkst+fkeSxUghjYacRPqyPdtQYTMTxLi0WEDiLh/eeZIOXvyTJMVDNdpP7PCvHKj UbvmD4JHXfPK56f/bwbNd63eJem8edKGcsuJ5TFFIIyr5fvsv7D5XJrg2AVYmEbFZ1sN fUQEAuLZ4WqDpYFUeEWRWwdNcEh4Okv0DTOlKYHi0PuHzvBVyJi65DHjEax9WpbKyWmK 1t39Snwf4LIo5wv4RoHnO47DmCIh0tA3qXUp17JpCc+dGFA1oWCfj41VTXsbr7UEMJBf 5pUceT7Y8uET2RHGMktMxypggnKcT4sc3XJyCmY1P8hQSDUM/mBJDbq21AAsL3ijkAR4 b+TA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:from:to:cc:references:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=6uRUHjT3H2vueqpdrwwP13xe2CMDcv0WafFpeyYI7lU=; b=Ttbe0enW28GkvvD4dElaRdHa9FhrL6wzCwZd2tqUb5M3h9GJ8SZjJaYr3qhs5gv/Rb t4m6jz4oQDJHANBspppCTZWhDT6SqauNEcOAbuDtDThvsi+2mXqVUgBy7glxnJdB5TMt BBTALXyNhn7tMhKk5p7trKeNaDPip8IO87kwKG31a9qw5LPKUr/UTSoIpSyaU+wl3Sp1 grH2jijQmrAMpB1D9AIv/MWzK4ydT2NdRa10cksuGI4YNPIKyignK9vdpUQZI0UvfeMf 2H+MDkRhQ2HBL0TAEg6th9IHPN5pzy2DdjKKWnxzzUVQ1yh3aVRRdK4JMysEzc9ltSlv /wnQ== X-Gm-Message-State: AGi0PuaD1dsQQiKYYLmmBaVTku+zITE3NWqA7wTcJGKG9yjokdeLRyFH +6RYWsRyiBAP3MXyj3kC+oUdIrrp X-Google-Smtp-Source: APiQypIugZXxUsd6hzBRHuCzJVvozH9gSOdzFAkV/cOyC5kvexLHlgQQHLEyOFzolrIVXQv3Be/QaA== X-Received: by 2002:ac2:46e5:: with SMTP id q5mr1912441lfo.11.1586297646938; Tue, 07 Apr 2020 15:14:06 -0700 (PDT) Received: from [192.168.2.145] (ppp91-78-208-152.pppoe.mtu-net.ru. [91.78.208.152]) by smtp.googlemail.com with ESMTPSA id l13sm12381613ljc.84.2020.04.07.15.14.05 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 07 Apr 2020 15:14:06 -0700 (PDT) Subject: Re: [RFC PATCH v6 6/9] media: tegra: Add Tegra210 Video input driver From: Dmitry Osipenko To: Sowjanya Komatineni , thierry.reding@gmail.com, jonathanh@nvidia.com, frankc@nvidia.com, hverkuil@xs4all.nl, sakari.ailus@iki.fi, helen.koike@collabora.com Cc: sboyd@kernel.org, linux-media@vger.kernel.org, devicetree@vger.kernel.org, linux-clk@vger.kernel.org, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org References: <1585963507-12610-1-git-send-email-skomatineni@nvidia.com> <1585963507-12610-7-git-send-email-skomatineni@nvidia.com> <200bb96e-2d07-764f-9e14-55538dc742fd@gmail.com> <23bfab09-b464-6e51-9843-06d13000e9b9@nvidia.com> <08cd31d5-e8b9-4d3a-fb0e-0e4462947d96@nvidia.com> <12a834ac-52b1-6dc0-7d3a-3e6a1fa85a2a@gmail.com> <760d071e-0cbc-b3eb-9231-fb9f9ecb44a6@nvidia.com> <9e317f65-8a02-3b15-cfec-8e0d8374130e@gmail.com> <97b35910-4c93-123a-43a0-eb14476ed0f3@nvidia.com> <84ad4e2d-6ac1-e1f4-1c55-5edaae850631@nvidia.com> <15a879b3-8fb9-6821-3cdc-104ba583ac12@gmail.com> Message-ID: Date: Wed, 8 Apr 2020 01:14:05 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <15a879b3-8fb9-6821-3cdc-104ba583ac12@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 08.04.2020 01:08, Dmitry Osipenko пишет: > 08.04.2020 00:08, Sowjanya Komatineni пишет: > ... >>>> I think you need a semaphore with resource count = 2. >>> we hold on to issuing capture if more than 2 buffers are queued and it >>> continues only after fifo has min 1 slot empty >> >> >> Just want to close on this part of feedback. Hope above explanation is >> clear regarding triggering/issuing at max 2 frame capture to VI HW and >> also regarding capture threads where they use wait_event_interruptible >> to prevent blocking waiting for buffers to be available for captures. >> >> So no changes related to this part are needed in v7. > From what I see in the code, you "hold on" by making kthread to spin in > a busy-loop while caps_inflight >= SYNCPT_FIFO_DEPTH. So some change > should be needed to prevent this. Looks like some other media drivers do: schedule_timeout_uninterruptible(1); to avoid CPU hogging when contention is detected.