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 01:08:27 +0300 Message-ID: <15a879b3-8fb9-6821-3cdc-104ba583ac12@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> <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> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <84ad4e2d-6ac1-e1f4-1c55-5edaae850631-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> Content-Language: en-US Sender: linux-tegra-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 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. The wait_event_interruptible seems should be okay. 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 56F83C2BB54 for ; Tue, 7 Apr 2020 22:08:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3163F20747 for ; Tue, 7 Apr 2020 22:08:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="b5fGARpq" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726602AbgDGWId (ORCPT ); Tue, 7 Apr 2020 18:08:33 -0400 Received: from mail-lj1-f194.google.com ([209.85.208.194]:34149 "EHLO mail-lj1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726406AbgDGWId (ORCPT ); Tue, 7 Apr 2020 18:08:33 -0400 Received: by mail-lj1-f194.google.com with SMTP id p10so5513492ljn.1; Tue, 07 Apr 2020 15:08:30 -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=+YQ6O1FoLb/MfQceNzDIXhdipEgwi9Vc6NSir8tVQ+0=; b=b5fGARpqiUJ7tcTmKi17zh32/umwOMmRpj5E7VyMWiIibjaXst8RmX8O8P35JUyxoB 6Srx0qIWoyb0R3sr5KBfDQoEnvEurTVoixuY6pKVzK6V0nZZaH1WLBHJCgODTyUnqSxc X49o7q+1BAjWXdEHWcb5RBPbkGePf3ZQCcrHIE5gVg8G7dqkVWkgDJtyVY50t+6i1vz7 9+Y6CsV3Op9HNxdA7AJcEIcqI4bhlCtefpVpxwuzjXqdpTabAAI1bMAa9VEIUEEBphEf Lr2sVn/gXiqQ8aZkkz6iklP4IDWSm7n0ZR9cfBzhbt+REFpmTKEw0cGFkseFcBPWz3N5 wEmA== 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=+YQ6O1FoLb/MfQceNzDIXhdipEgwi9Vc6NSir8tVQ+0=; b=Dp4ULi8Tx2TD3pOwYxK0SYA7e6/9aZK+GIh+WMGENsGl5IK8dOoRu/njwm/jGNfAYe 2wwi+rk5fzARxszGXJ89KPXhe/Sosf/lZ++TPa2/9tXIPA1HPM/IywlrEbkU2fVsQfQw etV1bdtw+FyG5hf36IGdiDpVYHw3MyWlJ5DPuHog02H4XnFY8KDD6AbkMtAlDaM4vLDl iqDtCQTe4wGUsdqN17Kffqw0w/EBrKPtb7zTWiMK9ozOCyG9iNegr3B7xs1B2PsRRxon J55CeNOegIBQS8C4Gyw2qgzaFWAzJQrpwsZTacWsTpS7wZKIwWvMcPvFhlxxrRVRelcF lkqQ== X-Gm-Message-State: AGi0Pub9aw+NbXq8RFYDMteL6jfWohVs82XHxfTmvN+4inkEsl3q9DEM 42+hYCf3oX/SWVjlpc+VHPWQE2sZ X-Google-Smtp-Source: APiQypIPFyOuiHqydgiWr6R4XGLm/DccgJs0gnd5vqagCP8wITfmTfFr2KFObqdKFiD8qLk0TEs8AA== X-Received: by 2002:a2e:7d09:: with SMTP id y9mr2964718ljc.146.1586297309354; Tue, 07 Apr 2020 15:08:29 -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 r23sm3140311lfi.33.2020.04.07.15.08.27 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 07 Apr 2020 15:08:28 -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> <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> From: Dmitry Osipenko Message-ID: <15a879b3-8fb9-6821-3cdc-104ba583ac12@gmail.com> Date: Wed, 8 Apr 2020 01:08:27 +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: <84ad4e2d-6ac1-e1f4-1c55-5edaae850631@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 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. The wait_event_interruptible seems should be okay.