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=-11.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 76310C433E2 for ; Sat, 12 Sep 2020 10:21:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2735B214D8 for ; Sat, 12 Sep 2020 10:21:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=es-iitr-ac-in.20150623.gappssmtp.com header.i=@es-iitr-ac-in.20150623.gappssmtp.com header.b="C9iKS0cn" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725848AbgILKVp (ORCPT ); Sat, 12 Sep 2020 06:21:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39632 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725833AbgILKVn (ORCPT ); Sat, 12 Sep 2020 06:21:43 -0400 Received: from mail-pj1-x1042.google.com (mail-pj1-x1042.google.com [IPv6:2607:f8b0:4864:20::1042]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BDBCEC061757 for ; Sat, 12 Sep 2020 03:21:42 -0700 (PDT) Received: by mail-pj1-x1042.google.com with SMTP id jw11so2902767pjb.0 for ; Sat, 12 Sep 2020 03:21:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=es-iitr-ac-in.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to :user-agent; bh=jHFu+b/0/eT6OdVOwdtsBa51JcAxFxVr3SZsKqJxj6s=; b=C9iKS0cnsYZ+7Kdq7IL37cQfqV1mbkqtUhEkotBb77Hxw2TsAlfTYYQqlMTncJRAtU 3oGyou+VzUBNbuU0oa9BVS6Vm6DYlXI7ByPY+M2Tx0nsN1/c04YUnjPu9p5mWqm+cuaM 2IlAz3/daCTiRHDdlwdLBtEVuxTg5mHisMyg2mXP8Al23YG0JQCyrkR5y/UIqQgEJNdz cz6CZZtuCGj1k7HpcraCg4W+mUmNnVpH6jk87AsaNGZ1gCUSneMEPS1WoxhmuKF5QnHp HBVMmwVpJvvDXAGyLaDomScplwtKUxr6vUuVoF05DZe88PIgKYtP5LEcTx6CbvnaLyD/ 4klg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to:user-agent; bh=jHFu+b/0/eT6OdVOwdtsBa51JcAxFxVr3SZsKqJxj6s=; b=VwBVXrXVplc5melE/ReFTdgFU9dssDkQmO6pNFpgOcOD+BFup9j9Qnbh+tfqPtD0F9 f7DIbdu6NYb6LTzSkyHEKIOzeD+GaeT0jCcxMgVUMMK00ewtO4p3UUaURxEqmZY4Wk7L Ad3zdDuONng+y8vqV9tf15kzF+nSxMa0Z7/UpRlaovbzvtD5c4fQUdCJI95VF6jN21rx tAjXpLWd3kWbapOYt/R0janviavR0xCyipUpSSn+BnvuLN1gL/ftNjXWLvcTvLVvEvZd vqOPJpOYT5k7TG6KFLLOBpIilY5rxLMUpgEP+6oHLgTQa+4UTXRCGpsu/zILzXwPElIl AIYA== X-Gm-Message-State: AOAM533jFSPCTmOxkHn9rMX5nsH5HGgUtdjn6QcBDXTZ3hm7RHU9UXZR nCT11N5uQmy3mXeyUBDLjhqUSA== X-Google-Smtp-Source: ABdhPJzRsbpYEkhF7G+FoqH5PbbZsFYM2xh55dCXI+fZnKz7tx9W1FKgOiTdiyrVmJ3jz4u0T/FcYA== X-Received: by 2002:a17:902:bccb:b029:d1:9be4:9d22 with SMTP id o11-20020a170902bccbb02900d19be49d22mr6543396pls.40.1599906100839; Sat, 12 Sep 2020 03:21:40 -0700 (PDT) Received: from kaaira-HP-Pavilion-Notebook ([2405:201:6801:484c:954a:305:9758:cc93]) by smtp.gmail.com with ESMTPSA id i9sm3752813pgb.37.2020.09.12.03.21.38 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Sat, 12 Sep 2020 03:21:40 -0700 (PDT) Date: Sat, 12 Sep 2020 15:51:34 +0530 From: Kaaira Gupta To: Kieran Bingham Cc: Dafna Hirschfeld , Helen Koike , Shuah Khan , Mauro Carvalho Chehab , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 4/9] media: vimc: Separate starting stream from pipeline initialisation Message-ID: <20200912102134.GC5022@kaaira-HP-Pavilion-Notebook> References: <20200819180442.11630-1-kgupta@es.iitr.ac.in> <20200819180442.11630-5-kgupta@es.iitr.ac.in> <20200821210123.GA28410@kaaira-HP-Pavilion-Notebook> <00896ada-3ef7-a1b5-ab7b-fe8a41fc4881@ideasonboard.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <00896ada-3ef7-a1b5-ab7b-fe8a41fc4881@ideasonboard.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 02, 2020 at 10:56:46AM +0100, Kieran Bingham wrote: > Hi Kaaira, Dafna, > > On 28/08/2020 21:37, Dafna Hirschfeld wrote: > > Hi, > > > > Am 21.08.20 um 23:01 schrieb Kaaira Gupta: > >> Hi, > >> > >> On Fri, Aug 21, 2020 at 05:11:23PM +0200, Dafna Hirschfeld wrote: > >>> > >>> > >>> Am 19.08.20 um 20:04 schrieb Kaaira Gupta: > >>>> Separate the process of initialising pipeline array from starting > >>>> streaming for all entities in path of a stream. This is needed because > >>>> multiple streams can stream, but only one pipeline object is needed. > >>>> > >>>> Process frames only for those entities in a pipeline which are > >>>> streaming. This is known through their use counts. > >>>> > >>>> Signed-off-by: Kaaira Gupta > >>>> --- > >>>>    .../media/test-drivers/vimc/vimc-streamer.c   | 95 > >>>> ++++++++++++++++--- > >>>>    1 file changed, 83 insertions(+), 12 deletions(-) > >>>> > >>>> diff --git a/drivers/media/test-drivers/vimc/vimc-streamer.c > >>>> b/drivers/media/test-drivers/vimc/vimc-streamer.c > >>>> index c1644d69686d..cc40ecabe95a 100644 > >>>> --- a/drivers/media/test-drivers/vimc/vimc-streamer.c > >>>> +++ b/drivers/media/test-drivers/vimc/vimc-streamer.c > >>>> @@ -40,33 +40,30 @@ static void > >>>> vimc_streamer_pipeline_terminate(struct vimc_stream *stream) > >>>>    } > >>>>    /** > >>>> - * vimc_streamer_pipeline_init - Initializes the stream structure > >>>> + * vimc_streamer_stream_start - Starts streaming for all entities > >>>> + * in a stream > >>>>     * > >>>> - * @stream: the pointer to the stream structure to be initialized > >>>>     * @ved:    the pointer to the vimc entity initializing the stream > >>>>     * > >>>> - * Initializes the stream structure. Walks through the entity graph to > >>>> - * construct the pipeline used later on the streamer thread. > >>>> - * Calls vimc_streamer_s_stream() to enable stream in all entities of > >>>> - * the pipeline. > >>>> + * Walks through the entity graph to call vimc_streamer_s_stream() > >>>> + * to enable stream in all entities in path of a stream. > >>>>     * > >>>>     * Return: 0 if success, error code otherwise. > >>>>     */ > >>>> -static int vimc_streamer_pipeline_init(struct vimc_stream *stream, > >>>> -                       struct vimc_ent_device *ved) > >>>> +static int vimc_streamer_stream_start(struct vimc_stream *stream, > >>>> +                      struct vimc_ent_device *ved) > >>>>    { > >>>>        struct media_entity *entity; > >>>>        struct video_device *vdev; > >>>>        struct v4l2_subdev *sd; > >>>> +    int stream_size = 0; > >>>>        int ret = 0; > >>>> -    stream->pipe_size = 0; > >>>> -    while (stream->pipe_size < VIMC_STREAMER_PIPELINE_MAX_SIZE) { > >>>> +    while (stream_size < VIMC_STREAMER_PIPELINE_MAX_SIZE) { > >>>>            if (!ved) { > >>>>                vimc_streamer_pipeline_terminate(stream); > >>>>                return -EINVAL; > >>>>            } > >>>> -        stream->ved_pipeline[stream->pipe_size++] = ved; > >>>>            if (is_media_entity_v4l2_subdev(ved->ent)) { > >>>>                sd = media_entity_to_v4l2_subdev(ved->ent); > >>>> @@ -104,6 +101,73 @@ static int vimc_streamer_pipeline_init(struct > >>>> vimc_stream *stream, > >>>>                            entity); > >>>>                ved = video_get_drvdata(vdev); > >>>>            } > >>>> +        stream_size++; > >>>> +    } > >>>> + > >>>> +    vimc_streamer_pipeline_terminate(stream); > >>>> +    return -EINVAL; > >>>> +} > >>>> + > >>>> +/** > >>>> + * vimc_streamer_pipeline_init - Initialises pipeline and pipe size > >>>> + * > >>>> + * @stream: the pointer to the stream structure > >>>> + * @ved:    the pointer to the vimc entity initializing the stream > >>>> pipeline > > Which entity is this? Is it the start, or the end of the pipeline? I.e. > the sensor? or the capture ? It is the capture, I will add it to the documentation..thanks > > >>>> + * > >>>> + * Walks through the entity graph to initialise ved_pipeline and > >>>> updates > >>>> + * pipe_size too. > >>>> + * > >>>> + * Return: 0 if success, error code otherwise. > >>>> + */ > >>>> +static int vimc_streamer_pipeline_init(struct vimc_stream *stream, > >>>> +                       struct vimc_ent_device *ved) > >>>> +{ > >>>> +    struct media_entity *entity; > >>>> +    struct media_device *mdev; > >>>> +    struct media_graph graph; > >>>> +    struct video_device *vdev; > >>>> +    struct v4l2_subdev *sd; > >>>> +    int ret; > >>>> + > >>>> +    entity = ved->ent; > >>>> +    mdev = entity->graph_obj.mdev; > >>>> + > >>>> +    ret = media_graph_walk_init(&graph, mdev); > >>>> +    if (ret) > >>>> +        return ret; > >>>> + > >>>> +    media_graph_walk_start(&graph, entity); > >>>> + > >>>> +    /* > >>>> +     * Start pipeline array initialisation from RAW Capture only to > >>>> get > >>>> +     * entities in the correct order of their frame processing. > >>>> +     */ > >>>> +    if (!strncmp(entity->name, "RGB", 3)) { > >>> > >>> I don't understand this condition, way is it good for? > >> > >> I have explained that later in the reply > > Matching on entity names is a bit awkward, as they could be changed I > guess quite easily, and easily missed in this string matching. Agreed, I need to think of a better way to prevent this > > I haven't fully understood this code block yet to work out if there's > another way we could do this though, but reading ahead I see there might > be a way to 'walk the graph' on a per-stream basis which might be a good > way of factoring this path. > > Although there still needs to be a construction of the paths available > to a stream which splits from the sensor. > > > >> > >>> > >>> I think the function should be generic and not assume names of entities > >>> or specific topology. > >> > >> It doesn't assume the topology, rather it is in place just to make sure > >> that the entities in ved_pipeline are in correct order. > >> > >>> > >>> > >>>> +        entity = media_graph_walk_next(&graph); > >>>> +        mdev = entity->graph_obj.mdev; > >>>> +        media_graph_walk_cleanup(&graph); > >>>> + > >>>> +        ret = media_graph_walk_init(&graph, mdev); > >>>> +        if (ret) > >>>> +            return ret; > >>>> +        media_graph_walk_start(&graph, entity); > > > > Hi, can you explain what this code does? > > Why does it start the search in the next entity? > > > >>>> +    } > >>>> + > >>>> +    while (stream->pipe_size < VIMC_STREAMER_PIPELINE_MAX_SIZE) { > >>>> +        if (is_media_entity_v4l2_subdev(entity)) { > >>>> +            sd = media_entity_to_v4l2_subdev(entity); > >>>> +            ved = v4l2_get_subdevdata(sd); > >>>> +        } else { > >>>> +            vdev = container_of(entity, struct video_device, entity); > >>>> +            ved = video_get_drvdata(vdev); > >>>> +        } > >>>> +        stream->ved_pipeline[stream->pipe_size++] = ved; > >>>> +        entity = media_graph_walk_next(&graph); > >>>> + > >>>> +        if (!strcmp(entity->name, > >>>> stream->ved_pipeline[0]->ent->name)) { > >>> > >>> I also don't understand this condition > >>> > >>>> +            media_graph_walk_cleanup(&graph); > >>>> +            return 0; > >>>> +        } > >>>>        } > >>> > >>> It is not clear what this function does, it looks like it adds to > >>> 'ved_pipeline' > >>> all entities that are connected to the video node, in addition to the > >>> entities > >>> that where there from previous calls, so some entities appear several > >>> times. > >> > >> This function returns all the entities in a pipe, weather they are > >> streaming or not. For example, if only the RAW Capture 1 streams, or > >> RGB/YUB capture streams, or both stream..in all three cases ved_pipeline > >> will have the same entities, in exactly same order, and all will occur > >> just once. > >> Since media_graph_walk goes to each node of the graph, it returns back > >> to the first one (as its a graph), hence the last condition, ie, > >> > >>     if (!strcmp(entity->name, stream->ved_pipeline[0]->ent->name)) { > >> > >> makes sure that the first entity is not added again to the array. > >> > >> First condition, ie > >> > >>     if (!strncmp(entity->name, "RGB", 3)) { > >> > >> Just makes sure that the search starts at RGB capture only. This is > >> because, in case of any other video node, the order of entities, as you > >> have mentioned later in the mail, will not be desirable, ie it won't > >> start at sensor and end at captures. So this condition just takes care > >> that all the entities in ved_pipeline array are in correct order > >> (starting at sensor, ending at captures). > > > > It is better to compare to the whole name of the entity to make it more > > clear. > > Also I think it is better to document that this function is called only > > upon the > > first streaming node. > > If this doesn't end up refactored with other helpers, then indeed a few > comments might help the readabilty here. The distinctions of each > re-initialisation of the graph walk are hard to interpret the purpose. > > > > > > > I still think this function should be independent of the topology. > > Maybe you can use Helen's patch that allow walking a graph only opposite > > to the link direction: https://patchwork.kernel.org/patch/11564899/ > > This ensures that the Sensor will be first in the graph walk. Then the > > streaming thread > > iterates the ved_pipeline from 0 upwards and not from 'pipe_size' > > downwards. > > Being able to use a direct helper to walk the pipeline cleanly sounds > promising indeed. > > I suspect at some point int he next patches though - I'm going to see > something that needs to have full visibility of all paths enabled from > the sensor, as I think I recall that the thread will then process all > (enabled) entities in a single pass. Yes, that exactly is the problem :( This helper (that dafna has shared) can walk through one path, while the thread (which processes the frames) needs to view all the entites in all connected paths > -- > Kieran > > > > > > Thanks, > > Dafna > > > > > > > >> > >> Thanks, > >> Kaaira > >> > >>> > >>> I think there is no need to use the graph walk here but to access the > >>> source entity > >>> in each iteration, the way done in vimc_streamer_stream_start > >>> also. > >>> I think the code should iterate here until it reaches an entity that > >>> is already streaming, > >>> this means that the entity is already in the `ved_pipeline`, also you > >>> should make sure > >>> that the sensor is the first entity that process a frame, therefore > >>> the sensor should be > >>> at the end/start of the list of entities. Generally each entity > >>> should appear exactly once > >>> in the 'ved_pipeline' array and the entities should be ordered such > >>> that when calling 'process_frame' > >>> on one entity should be after calling 'process_frame' on its source > >>> entity. > >>> maybe it is easyer to implement if 'ved_pipeline' is a linked list. > >>> > >>> Thanks, > >>> Dafna > >>> > >>>>        vimc_streamer_pipeline_terminate(stream); > >>>> @@ -138,8 +202,11 @@ static int vimc_streamer_thread(void *data) > >>>>            for (i = stream->pipe_size - 1; i >= 0; i--) { > >>>>                ved = stream->ved_pipeline[i]; > >>>> -            ret = ved->process_frame(ved); > >>>> +            if (atomic_read(&ved->use_count) == 0) > >>>> +                continue; > >>>> + > >>>> +            ret = ved->process_frame(ved); > >>>>                if (ret) > >>>>                    break; > >>>>            } > >>>> @@ -179,6 +246,10 @@ int vimc_streamer_s_stream(struct vimc_stream > >>>> *stream, > >>>>            if (stream->kthread) > >>>>                return 0; > >>>> +        ret = vimc_streamer_stream_start(stream, ved); > >>>> +        if (ret) > >>>> +            return ret; > >>>> + > >>>>            ret = vimc_streamer_pipeline_init(stream, ved); > >>>>            if (ret) > >>>>                return ret; > >>>> > > -- > Regards > -- > Kieran