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 96B75C47247 for ; Thu, 30 Apr 2020 16:30:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7673C2082E for ; Thu, 30 Apr 2020 16:30:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="sOWMM3UK" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726738AbgD3Qaa (ORCPT ); Thu, 30 Apr 2020 12:30:30 -0400 Received: from hqnvemgate25.nvidia.com ([216.228.121.64]:13064 "EHLO hqnvemgate25.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726130AbgD3Qa2 (ORCPT ); Thu, 30 Apr 2020 12:30:28 -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 09:29:21 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Thu, 30 Apr 2020 09:30:28 -0700 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Thu, 30 Apr 2020 09:30:28 -0700 Received: from DRHQMAIL107.nvidia.com (10.27.9.16) by HQMAIL101.nvidia.com (172.20.187.10) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Thu, 30 Apr 2020 16:30:28 +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 16:30:26 +0000 Subject: Re: [RFC PATCH v11 6/9] media: tegra: Add Tegra210 Video input driver From: Sowjanya Komatineni 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> Message-ID: <7d31d24f-f353-7e82-3ff9-cdba8b773d1e@nvidia.com> Date: Thu, 30 Apr 2020 09:29:00 -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=1588264161; bh=2DroO8GJPT0AtZeSQK8ueROEdYIu6Ovs1ect3MjQzPE=; h=X-PGP-Universal:Subject:From:To:CC:References:Message-ID:Date: User-Agent:MIME-Version:In-Reply-To:X-Originating-IP: X-ClientProxiedBy:Content-Type:Content-Transfer-Encoding: Content-Language; b=sOWMM3UKIfeFYgOV3uLGzs75tw9iBGuZFODCZwKiHiL0dCOJKwlbBZuiVacayju7e 27d2YHXn6JgrBPa+b3Hh61DgKBgkUmucxkOTNu8c+vgIAULPzB8dey7Yw/htsnhCCi sgpgv5qzEi2Xjxe45K2l7wKPHL30bR76787qy9sYYntYjM1k3MGUtvwlC2oBaqb24e T3cqJ8NssY3wetqt+VdP8KOmm25bnSyqK5rGV9hT8NdshtcuZqFpdbsfHCebZ31M2P +9bqvOZCh/SYfCppuNEApgaVu0DmUSJyW0MHRm1PjX133UeOdd26rXX75kPw9uNcGz 6VU8iQUbmqIyA== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/30/20 9:04 AM, Sowjanya Komatineni wrote: > > 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) >>>>> +{ >>>>> +=C2=A0=C2=A0=C2=A0 struct tegra_vi_channel *chan =3D data; >>>>> +=C2=A0=C2=A0=C2=A0 struct tegra_channel_buffer *buf; >>>>> + >>>>> +=C2=A0=C2=A0=C2=A0 set_freezable(); >>>>> + >>>>> +=C2=A0=C2=A0=C2=A0 while (1) { >>>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 try_to_freeze(); >>>> I guess it won't be great to freeze in the middle of a capture=20 >>>> process, so: >>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (list_empty(&chan->done)= ) >>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 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) && >> =C2=A0=C2=A0=C2=A0=C2=A0 list_empty(&chan->done)) >> =C2=A0=C2=A0=C2=A0=C2=A0try_to_freeze(); > > good to freeze when not in middle of the frame capture but why should=20 > we 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=20 > we can freeze after capture done. This also don't need to check for=20 > list_empty with freeze to allow between frame captures. > Also if we add check for both lists empty, freeze is not allowed as long=20 as streaming is going on and in case of continuous streaming freeze will=20 never happen.