From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sowjanya Komatineni Subject: Re: [RFC PATCH v6 6/9] media: tegra: Add Tegra210 Video input driver Date: Mon, 6 Apr 2020 13:55:12 -0700 Message-ID: <08cd31d5-e8b9-4d3a-fb0e-0e4462947d96@nvidia.com> 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> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Dmitry Osipenko , 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 List-Id: linux-tegra@vger.kernel.org On 4/6/20 1:53 PM, Dmitry Osipenko wrote: > External email: Use caution opening links or attachments > > > 06.04.2020 23:50, Sowjanya Komatineni =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >> On 4/6/20 1:45 PM, Dmitry Osipenko wrote: >>> External email: Use caution opening links or attachments >>> >>> >>> 04.04.2020 04:25, Sowjanya Komatineni =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >>>> +static int chan_capture_kthread_start(void *data) >>>> +{ >>>> + struct tegra_vi_channel *chan =3D data; >>>> + struct tegra_channel_buffer *buf; >>>> + int err =3D 0; >>>> + int caps_inflight; >>>> + >>>> + set_freezable(); >>>> + >>>> + while (1) { >>>> + try_to_freeze(); >>>> + >>>> + wait_event_interruptible(chan->start_wait, >>>> + !list_empty(&chan->capture) || >>>> + kthread_should_stop()); >>>> + /* >>>> + * Frame start and MW_ACK_DONE syncpoint condition >>>> FIFOs are >>>> + * of max depth 2. So make sure max 2 capture requests a= re >>>> + * in process by the hardware at a time. >>>> + */ >>>> + while (!(kthread_should_stop() || >>>> list_empty(&chan->capture))) { >>>> + caps_inflight =3D chan->capture_reqs - >>>> chan->sequence; >>>> + /* >>>> + * Source is not streaming if error is non-zero. >>>> + * So, do not dequeue buffers on capture error >>>> or when >>>> + * syncpoint requests in FIFO are full. >>>> + */ >>>> + if (err || caps_inflight >=3D SYNCPT_FIFO_DEPTH) >>>> + break; >>> Am I understanding correctly that this thread will take 100% CPU, >>> spinning here, if more than 2 frame-captures queued? >> on more than 2 frames captures, it breaks thread and on next wakeup it >> continues > The wait_event() won't wait if condition is true. condition is checked when waitqueue is woken up 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=-2.5 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 CF201C2BA80 for ; 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by hqpgpgate101.nvidia.com on Mon, 06 Apr 2020 13:55:15 -0700 Received: from DRHQMAIL107.nvidia.com (10.27.9.16) by HQMAIL109.nvidia.com (172.20.187.15) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Mon, 6 Apr 2020 20:55:14 +0000 Received: from [10.2.164.193] (10.124.1.5) by DRHQMAIL107.nvidia.com (10.27.9.16) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Mon, 6 Apr 2020 20:55:13 +0000 Subject: Re: [RFC PATCH v6 6/9] media: tegra: Add Tegra210 Video input driver To: Dmitry Osipenko , , , , , , CC: , , , , , 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> From: Sowjanya Komatineni Message-ID: <08cd31d5-e8b9-4d3a-fb0e-0e4462947d96@nvidia.com> Date: Mon, 6 Apr 2020 13:55:12 -0700 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: X-Originating-IP: [10.124.1.5] X-ClientProxiedBy: HQMAIL101.nvidia.com (172.20.187.10) To DRHQMAIL107.nvidia.com (10.27.9.16) Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: quoted-printable Content-Language: en-US DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1586206463; bh=YnvtQsMn5rdC0Ko/RPVqNGcCUm5QPvKwp6GatKxWssk=; h=X-PGP-Universal:Subject:To:CC:References:From:Message-ID:Date: User-Agent:MIME-Version:In-Reply-To:X-Originating-IP: X-ClientProxiedBy:Content-Type:Content-Transfer-Encoding: Content-Language; b=bW1MmzrBrn4j8HcsWvWtV5uHCW4bom4CIRnjFomFRKi190jhbZndHStaEzv871ylV 3ejsEaCikv1vLfL6g56f2K9TzmLJE0rLj9h+UvR4DOUHmHfA7o7niL+Wn40MtYRr4h FtgxbhOhFRKS0GODfhKUdKeLw2Gmjsn9LXNi1XTfZaDf9mhD6N6OdQKrEfn1RylttA ztg42f1fWD5kgEkyBYJ1ctgho7PtR2K/uNt139nxlP/zoIaVwtHhppOMvDhOZU5ZT/ lc94UJg4RST9A9VqO7kkBevjYn/AhlGky+9PUvIeKdwefGUU3iMABcyCD0hv9ohAIV yOH0ZvVuO7CVA== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/6/20 1:53 PM, Dmitry Osipenko wrote: > External email: Use caution opening links or attachments > > > 06.04.2020 23:50, Sowjanya Komatineni =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >> On 4/6/20 1:45 PM, Dmitry Osipenko wrote: >>> External email: Use caution opening links or attachments >>> >>> >>> 04.04.2020 04:25, Sowjanya Komatineni =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >>>> +static int chan_capture_kthread_start(void *data) >>>> +{ >>>> + struct tegra_vi_channel *chan =3D data; >>>> + struct tegra_channel_buffer *buf; >>>> + int err =3D 0; >>>> + int caps_inflight; >>>> + >>>> + set_freezable(); >>>> + >>>> + while (1) { >>>> + try_to_freeze(); >>>> + >>>> + wait_event_interruptible(chan->start_wait, >>>> + !list_empty(&chan->capture) || >>>> + kthread_should_stop()); >>>> + /* >>>> + * Frame start and MW_ACK_DONE syncpoint condition >>>> FIFOs are >>>> + * of max depth 2. So make sure max 2 capture requests a= re >>>> + * in process by the hardware at a time. >>>> + */ >>>> + while (!(kthread_should_stop() || >>>> list_empty(&chan->capture))) { >>>> + caps_inflight =3D chan->capture_reqs - >>>> chan->sequence; >>>> + /* >>>> + * Source is not streaming if error is non-zero. >>>> + * So, do not dequeue buffers on capture error >>>> or when >>>> + * syncpoint requests in FIFO are full. >>>> + */ >>>> + if (err || caps_inflight >=3D SYNCPT_FIFO_DEPTH) >>>> + break; >>> Am I understanding correctly that this thread will take 100% CPU, >>> spinning here, if more than 2 frame-captures queued? >> on more than 2 frames captures, it breaks thread and on next wakeup it >> continues > The wait_event() won't wait if condition is true. condition is checked when waitqueue is woken up