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 <kgu...@es.iitr.ac.in> > >>>> --- > >>>> .../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