From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sowjanya Komatineni Subject: Re: [RFC PATCH v11 6/9] media: tegra: Add Tegra210 Video input driver Date: Thu, 30 Apr 2020 09:04:40 -0700 Message-ID: References: <1588197606-32124-1-git-send-email-skomatineni@nvidia.com> <1588197606-32124-7-git-send-email-skomatineni@nvidia.com> <4da289e6-036f-853b-beb4-379d6462adb0@gmail.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-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Dmitry Osipenko , 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 On 4/30/20 7:13 AM, Dmitry Osipenko wrote: > 30.04.2020 17:02, Dmitry Osipenko =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >> 30.04.2020 16:56, Dmitry Osipenko =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >>> 30.04.2020 01:00, Sowjanya Komatineni =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >>>> +static int chan_capture_kthread_finish(void *data) >>>> +{ >>>> + struct tegra_vi_channel *chan =3D data; >>>> + struct tegra_channel_buffer *buf; >>>> + >>>> + set_freezable(); >>>> + >>>> + while (1) { >>>> + try_to_freeze(); >>> I guess it won't be great to freeze in the middle of a capture process,= so: >>> if (list_empty(&chan->done)) >>> try_to_freeze(); >> And here should be some locking protection in order not race with the >> chan_capture_kthread_start because kthread_finish could freeze before >> kthread_start. > Or maybe both start / finish threads should simply be allowed to freeze > only when both capture and done lists are empty. > > if (list_empty(&chan->capture) && > list_empty(&chan->done)) > try_to_freeze(); good to freeze when not in middle of the frame capture but why should we=20 not allow freeze in between captures? Other drivers do allow freeze in between frame captures. I guess we can freeze before dequeue for capture and in finish thread we=20 can freeze after capture done. This also don't need to check for=20 list_empty with freeze to allow between frame captures. 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=-2.4 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 C2242C47254 for ; Thu, 30 Apr 2020 16:06:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A1F4620775 for ; Thu, 30 Apr 2020 16:06:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="kP9ln9IF" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728321AbgD3QGK (ORCPT ); Thu, 30 Apr 2020 12:06:10 -0400 Received: from hqnvemgate25.nvidia.com ([216.228.121.64]:10786 "EHLO hqnvemgate25.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727813AbgD3QGJ (ORCPT ); Thu, 30 Apr 2020 12:06:09 -0400 Received: from hqpgpgate101.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate25.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Thu, 30 Apr 2020 09:05:00 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Thu, 30 Apr 2020 09:06:07 -0700 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Thu, 30 Apr 2020 09:06:07 -0700 Received: from DRHQMAIL107.nvidia.com (10.27.9.16) by HQMAIL105.nvidia.com (172.20.187.12) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Thu, 30 Apr 2020 16:06:07 +0000 Received: from [10.2.165.152] (10.124.1.5) by DRHQMAIL107.nvidia.com (10.27.9.16) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Thu, 30 Apr 2020 16:06:06 +0000 Subject: Re: [RFC PATCH v11 6/9] media: tegra: Add Tegra210 Video input driver To: Dmitry Osipenko , , , , , , CC: , , , , , References: <1588197606-32124-1-git-send-email-skomatineni@nvidia.com> <1588197606-32124-7-git-send-email-skomatineni@nvidia.com> <4da289e6-036f-853b-beb4-379d6462adb0@gmail.com> From: Sowjanya Komatineni Message-ID: Date: Thu, 30 Apr 2020 09:04:40 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: X-Originating-IP: [10.124.1.5] X-ClientProxiedBy: HQMAIL105.nvidia.com (172.20.187.12) 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=1588262700; bh=eWajUdI0iXeAXeqVD5ZpEmRaSpEhM1U8KfCosqzO194=; 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=kP9ln9IFyG1CyD2zYD6UBRJU+3nqtrfnnZ+cS/JlbzMx3B5faTPLBdCdqyTod9yo1 Z0Z2LBvNwQOpWFZIlo0fsv987r878bT2zeUtFfUToRuBf1Lh/HgCJgU7bLrKBMWn3Q 7EPPKclFWEMjk0R/r47l9T1m3+0SRS07OY7Pci/cE1nIgNUWDe6tk+Kayl8v2RJ0Rk 3nt0YCCT4XfBt1BFf++ZQhEXx6KRIn9v+noVua6ZqWw5Skg8oeWfj68av04Fza1i/d F7E8EIRMAtO/MowkXFoanRyv6lWSbQx/oMz+9gxgwUq+u9RKO8pXG3cOzg4ztuNvIk 5iYSGa7WbeIhA== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/30/20 7:13 AM, Dmitry Osipenko wrote: > 30.04.2020 17:02, Dmitry Osipenko =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >> 30.04.2020 16:56, Dmitry Osipenko =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >>> 30.04.2020 01:00, Sowjanya Komatineni =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >>>> +static int chan_capture_kthread_finish(void *data) >>>> +{ >>>> + struct tegra_vi_channel *chan =3D data; >>>> + struct tegra_channel_buffer *buf; >>>> + >>>> + set_freezable(); >>>> + >>>> + while (1) { >>>> + try_to_freeze(); >>> I guess it won't be great to freeze in the middle of a capture process,= so: >>> if (list_empty(&chan->done)) >>> try_to_freeze(); >> And here should be some locking protection in order not race with the >> chan_capture_kthread_start because kthread_finish could freeze before >> kthread_start. > Or maybe both start / finish threads should simply be allowed to freeze > only when both capture and done lists are empty. > > if (list_empty(&chan->capture) && > list_empty(&chan->done)) > try_to_freeze(); good to freeze when not in middle of the frame capture but why should we=20 not allow freeze in between captures? Other drivers do allow freeze in between frame captures. I guess we can freeze before dequeue for capture and in finish thread we=20 can freeze after capture done. This also don't need to check for=20 list_empty with freeze to allow between frame captures.