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: Mon, 6 Apr 2020 23:56:28 +0300 Message-ID: <12a834ac-52b1-6dc0-7d3a-3e6a1fa85a2a@gmail.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> <08cd31d5-e8b9-4d3a-fb0e-0e4462947d96@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <08cd31d5-e8b9-4d3a-fb0e-0e4462947d96-DDmLM1+adcrQT0dZR+AlfA@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 06.04.2020 23:55, Sowjanya Komatineni пишет: > > 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 пишет: >>> 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 пишет: >>>>> +static int chan_capture_kthread_start(void *data) >>>>> +{ >>>>> +     struct tegra_vi_channel *chan = data; >>>>> +     struct tegra_channel_buffer *buf; >>>>> +     int err = 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 are >>>>> +              * in process by the hardware at a time. >>>>> +              */ >>>>> +             while (!(kthread_should_stop() || >>>>> list_empty(&chan->capture))) { >>>>> +                     caps_inflight = 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 >= 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 https://elixir.bootlin.com/linux/v5.6.2/source/include/linux/wait.h#L462 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, URIBL_BLOCKED,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 8620FC2BB54 for ; Mon, 6 Apr 2020 20:56:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 64CAF2072F for ; Mon, 6 Apr 2020 20:56:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="BOkZDwRS" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726403AbgDFU4e (ORCPT ); Mon, 6 Apr 2020 16:56:34 -0400 Received: from mail-lj1-f196.google.com ([209.85.208.196]:36192 "EHLO mail-lj1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726084AbgDFU4e (ORCPT ); Mon, 6 Apr 2020 16:56:34 -0400 Received: by mail-lj1-f196.google.com with SMTP id b1so1287781ljp.3; Mon, 06 Apr 2020 13:56:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=m4YEjHOQzSNFd68a9Mm226UNhvqPTovnFAMO2q+cqdA=; b=BOkZDwRScSAmZdBwIMqxO7xvW25h1+bgaMCpus/nSP38a+fuh2+1vyqAhnr6+JHejs 0xeC497nMSL4N3EByOdAQOu0ll0R8nJEHQtl76i+TWEMggAfB6XlaPRzuA5ccoSBc3Ot PxPA3hTz5fopYjJTlPJGfCSHZSOr2PtvCGN8BE50gGd1ef5cP760IFyLKQdK1KDZii7k Bh1gE0wDBrhmSbEw0AaKsB1h41I/9wgLJxPpbDlDuy3gS6qtjCBbAHKeCR3zOt1ITbhU uw2uT1fQdH5UTQZXNTaxF8e4Tmwce3NVRRSCnNO61mlQ8FcbF8otyu6AHzxAhmpKo0Oo FzkA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=m4YEjHOQzSNFd68a9Mm226UNhvqPTovnFAMO2q+cqdA=; b=mfXJuZr5ZP2U5UXGfzqQncDvl/rzlfAWffjz/CuTTJo1pralZJs2srIlvuaUnBaxPy EHrCwsa/rrC0f0dfJqJBw+JrhLOu7hfN3jV/ScChJu0J+X5UBha7b0jhZsiCQHxNEX4T ewzFFXKkLxNSuYVi80E0c/pWIdYnR++Qszt2lFeDhg+54BWwzy3r6xZYiUK2bZ6mkLIb 68G5qAas+kl6Csew6d76vWUEc/o2+TO/08NIQeMrqSCVxZPFJLAolgbWgNt4VlKgXVkT 3d13QmQ3DNGqo/OxDBtnbjaVrXpe6Vv+ABC7/+xekmth5NK7x7p4pIRybv2M/I8deKHW JODQ== X-Gm-Message-State: AGi0Pube9z9KEgDrdlkdQkK3UAVtyPqGmtYuigrMqPhQJjdud1Wdh49M AE1vSoZHqlZ+Zurjs5U0nOvmcstT X-Google-Smtp-Source: APiQypLfBmFvm+GNYEaZbaANGod8VKUywm1iPT1ciwDTXi5y2Ljca8haVWjt4Whmk1t4FiB1RfQaRQ== X-Received: by 2002:a2e:a310:: with SMTP id l16mr699762lje.255.1586206590575; Mon, 06 Apr 2020 13:56:30 -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 x17sm10572315ljc.33.2020.04.06.13.56.28 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 06 Apr 2020 13:56:29 -0700 (PDT) Subject: Re: [RFC PATCH v6 6/9] media: tegra: Add Tegra210 Video input driver 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> From: Dmitry Osipenko Message-ID: <12a834ac-52b1-6dc0-7d3a-3e6a1fa85a2a@gmail.com> Date: Mon, 6 Apr 2020 23:56:28 +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: <08cd31d5-e8b9-4d3a-fb0e-0e4462947d96@nvidia.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 06.04.2020 23:55, Sowjanya Komatineni пишет: > > 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 пишет: >>> 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 пишет: >>>>> +static int chan_capture_kthread_start(void *data) >>>>> +{ >>>>> +     struct tegra_vi_channel *chan = data; >>>>> +     struct tegra_channel_buffer *buf; >>>>> +     int err = 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 are >>>>> +              * in process by the hardware at a time. >>>>> +              */ >>>>> +             while (!(kthread_should_stop() || >>>>> list_empty(&chan->capture))) { >>>>> +                     caps_inflight = 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 >= 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 https://elixir.bootlin.com/linux/v5.6.2/source/include/linux/wait.h#L462