On Wed, Aug 05, 2020 at 12:19:52AM +0530, Kaaira Gupta wrote: > Hi > > On Tue, Aug 04, 2020 at 11:24:56AM +0100, Kieran Bingham wrote: > > Hi Kaaira, > > > > On 31/07/2020 18:22, Kaaira Gupta wrote: > > > Hi everyone, > > > > > > On Wed, Jul 29, 2020 at 05:24:25PM +0200, Dafna Hirschfeld wrote: > > >> > > >> > > >> On 29.07.20 15:27, Kieran Bingham wrote: > > >>> Hi Dafna, Kaaira, > > >>> > > >>> On 29/07/2020 14:16, Dafna Hirschfeld wrote: > > >>>> > > >>>> > > >>>> On 29.07.20 15:05, Kieran Bingham wrote: > > >>>>> Hi Dafna, > > >>>>> > > >>>>> On 28/07/2020 15:00, Dafna Hirschfeld wrote: > > >>>>>> > > >>>>>> > > >>>>>> On 28.07.20 14:07, Dafna Hirschfeld wrote: > > >>>>>>> Hi > > >>>>>>> > > >>>>>>> On 28.07.20 13:39, Kaaira Gupta wrote: > > >>>>>>>> On Mon, Jul 27, 2020 at 02:54:30PM -0300, Helen Koike wrote: > > >>>>>>>>> Hi, > > >>>>>>>>> > > >>>>>>>>> On 7/27/20 11:31 AM, Kieran Bingham wrote: > > >>>>>>>>>> Hi all, > > >>>>>>>>>> > > >>>>>>>>>> +Dafna for the thread discussion, as she's missed from the to/cc > > >>>>>>>>>> list. > > >>>>>>>>>> > > >>>>>>>>>> > > >>>>>>>>>> On 24/07/2020 13:21, Kaaira Gupta wrote: > > >>>>>>>>>>> On Fri, Jul 24, 2020 at 02:15:21PM +0200, Niklas Söderlund wrote: > > >>>>>>>>>>> Hi, > > >>>>>>>>>>> > > >>>>>>>>>>>> Hi Kaaira, > > >>>>>>>>>>>> > > >>>>>>>>>>>> Thanks for your work. > > >>>>>>>>>>> > > >>>>>>>>>>> Thanks for yours :D > > >>>>>>>>>>> > > >>>>>>>>>>>> > > >>>>>>>>>>>> On 2020-07-24 17:32:10 +0530, Kaaira Gupta wrote: > > >>>>>>>>>>>>> This is version 2 of the patch series posted by Niklas for > > >>>>>>>>>>>>> allowing > > >>>>>>>>>>>>> multiple streams in VIMC. > > >>>>>>>>>>>>> The original series can be found here: > > >>>>>>>>>>>>> https://patchwork.kernel.org/cover/10948831/ > > >>>>>>>>>>>>> > > >>>>>>>>>>>>> This series adds support for two (or more) capture devices to be > > >>>>>>>>>>>>> connected to the same sensors and run simultaneously. Each > > >>>>>>>>>>>>> capture device > > >>>>>>>>>>>>> can be started and stopped independent of each other. > > >>>>>>>>>>>>> > > >>>>>>>>>>>>> Patch 1/3 and 2/3 deals with solving the issues that arises once > > >>>>>>>>>>>>> two > > >>>>>>>>>>>>> capture devices can be part of the same pipeline. While 3/3 > > >>>>>>>>>>>>> allows for > > >>>>>>>>>>>>> two capture devices to be part of the same pipeline and thus > > >>>>>>>>>>>>> allows for > > >>>>>>>>>>>>> simultaneously use. > > >>>>>>> > > >>>>>>> I wonder if these two patches are enough, since each vimc entity also > > >>>>>>> have > > >>>>>>> a 'process_frame' callback, but only one allocated frame. That means > > >>>>>>> that the 'process_frame' can be called concurrently by two different > > >>>>>>> streams > > >>>>>>> on the same frame and cause corruption. > > >>>>>>> > > >>>>>> > > >>>>>> I think we should somehow change the vimc-stream.c code so that we have > > >>>>>> only > > >>>>>> one stream process per pipe. So if one capture is already streaming, > > >>>>>> then the new > > >>>>>> capture that wants to stream uses the same thread so we don't have two > > >>>>>> threads > > >>>>>> both calling 'process_frame'. > > >>>>> > > >>>>> > > >>>>> Yes, I think it looks and sounds like there are two threads running when > > >>>>> there are two streams. > > >>>>> > > >>>>> so in effect, although they 'share a pipe', aren't they in effect just > > >>>>> sending two separate buffers through their stream-path? > > >>>>> > > >>>>> If that's the case, then I don't think there's any frame corruption, > > >>>>> because they would both have grabbed their own frame separately. > > >>>> > > >>>> But each entity allocates just one buffer. So the same buffer is used for > > >>>> both stream. > > >>> > > >>> Aha, ok, I hadn't realised there was only a single buffer available in > > >>> the pipeline for each entity. Indeed there is a risk of corruption in > > >>> that case. > > >>> > > >>>> What for example can happen is that the debayer of one stream can read the > > >>>> sensor's buffer while the sensor itself writes to the buffer for the other > > >>>> stream. > > >>> > > >>> > > >>> So, In that case, we have currently got a scenario where each 'stream' > > >>> really is operating it's own pipe (even though all components are reused). > > >>> > > >>> Two questions: > > >>> > > >>> Is this acceptable, and we should just use a mutex to ensure the buffers > > >>> are not corrupted, but essentially each stream is a separate temporal > > >>> capture? > > >>> > > >>> > > >>> Or B: > > >>> > > >>> Should we refactor to make sure that there is a single thread, and the > > >>> code which calls process_frame on each entity should become aware of the > > >>> potential for multiple paths at the point of the sensor. > > >>> > > >>> > > >>> I suspect option B is really the 'right' path to take, but it is more > > >>> complicated of course. > > >> > > >> I also think option B is preferable. > > >> > > >> Maybe we can add a bool field 'is_streaming' to struct 'vimc_ent_device' > > >> The stream thread can do a BFS scan from the sensor up to the captures > > >> and call the 'process_frame' for each entity if 'is_streaming == true'. > > >> When a new capture wants to stream it sets 'is_streaming = true' > > >> on the entities on his streaming path. > > > > > > It is s_stream(enable) that initialises a streaming pipeline, ie the one with > > > those components of the pipeline which are in stream path and then runs a > > > thread which calls process_frame on each and passes the frame to the > > > next entity in streaming pipeline. So currently, one thread is for one > > > "streaming pipeline". So there are two options I can think of if a > > > single thread is required, > > > > > > 1. Not creating a streaming pipeline, rather create a graph(?) which > > > connects both say Raw capture 1 and debayer B to sensor B if two streams > > > are asked for, and only one of them if one stream is asked..that will > > > not be a property of streamer, so I am not sure where it should be kept. > > > Then I could move creating a thread out of s_stream. Creating the thread > > > should wait for entire pipeline to be created, ie s_stream(enable) to > > > must be called by both the captures, and a graph made of all pipeline > > > components before thread initialisation starts. I am not sure how this > > > should be implemented. > > > > The graph already exists, and can be walked through the media controller > > right? > > Yes, but actually, the current implementation of the thread does not > walk through the entire pipeline, rather ved_pipeline, which is the > portions of the pipeline which come in the streaming path of a stream > which calls the thread. This also answers your doubt why the pipeline is > decreamenting (which you have asked later in the mail). ved_pipeline is > an array of the entities in the path of the stream starting from > capture. Hence my suggestion was if I should make a data structure (a > graph) which holds all the entities in one or more stream path. > > > > > > > > 2. Another option is to check if a stream already exists (by creating it > > > a property of vimc to keep a track of no. of streams maybe?), if it is > > > already present I could take the previous output of sensor (but > > > then it will have to be stored, so i don't think this is a nice idea), > > > and use it further (but thread will be different in this case). > > > > I don't think I understand this one... > > I meant that to start a thread for the driver, rather than each stream, > maybe instead of creating a graph (as in the first option), maybe the > druver could know the number of steams alsready running, and hence when > s_stream is called for another, it knows how many and what type of > streams are running, which can then /know/ which entity's output of > process_frame(previous stream) to give on to the current stream. But I > wasn't sure about the implementation of the /knwing/part without > hardcoding it to take output from the sensor. But since that is the only > topology (hardcoded)we have currently, maybe that can be a solution, > hence I asked. The idea is actually almost same as the pseudo code/implementation you wrote below :D > > > > > > > > What can be a better design for VIMC to have a single thread if two > > > streams are asked (apart/of the options I mentioned)? > > > > How about adding a count in s_stream so that the thread only gets > > started when the use count is > 0, and stopped when the usage < 1. > > > > That handles making sure that only one thread is available. > > > > All calls into s_stream() will need to take a lock/mutex to protect / > > prevent any action from occurring while the thread is performing a > > process of the pipeline. > > > > > > static int vimc_streamer_thread(void *data) > > { > > struct vimc_stream *stream = data; > > u8 *frame = NULL; > > int i; > > > > set_freezable(); > > > > for (;;) { > > try_to_freeze(); > > if (kthread_should_stop()) > > break; > > > > + /* take lock shared with s_stream */ > > > > for (i = stream->pipe_size - 1; i >= 0; i--) { > > frame = stream->ved_pipeline[i]->process_frame( > > stream->ved_pipeline[i], frame); > > if (!frame || IS_ERR(frame)) > > break; > > } > > > > + /* Release lock/mutex shared with s_stream > > > > //wait for 60hz > > set_current_state(TASK_UNINTERRUPTIBLE); > > schedule_timeout(HZ / 60); > > } > > > > return 0; > > } > > > > > > > > And you'll need to make the code which processes the pipeline aware of > > the fact that there may be two pipelines to fulfil: > > > > Pseudo patch/code: > > > > static int vimc_streamer_thread(void *data) > > { > > - struct vimc_stream *stream = data; > > + /* Something which knows about the whole device */ > > + struct xxxxx *yyy = data; > > > > + u8 *raw; > > u8 *frame = NULL; > > int i; > > > > set_freezable(); > > > > for (;;) { > > try_to_freeze(); > > if (kthread_should_stop()) > > break; > > > > /* take lock shared with s_stream */ > > > > + /* Process the sensor first */ > > + raw = stream->ved_pipeline[sensor]->process_frame(..); > > + error check; > > > > + /* (If connected) Process stream 1 */ > > + if (raw) > > + frame = stream->ved_pipeline[raw]->process_frame(); > > + error check; > > > > + /* If connected process the rest of the pipe */ > > + for (i = after sensor; end_entity; i++) { > > frame = stream->ved_pipeline[i]->process_frame( > > stream->ved_pipeline[i], frame); > > if (!frame || IS_ERR(frame)) > > break; > > } > > > > /* Release lock/mutex shared with s_stream > > > > //wait for 60hz > > set_current_state(TASK_UNINTERRUPTIBLE); > > schedule_timeout(HZ / 60); > > } > > > > return 0; > > } > > > > > > > > I may have missed something as the original loop was decrementing and > > going backwards through the entities in stream->ved_pipeline. > > > > I guess splitting that all out so instead it starts at the sensor, and > > just walks the graph (handling any running/connected fork to two > > entities appropriately) in a neater way would be another option rather > > than hardcoding it, but either way the thread needs to operate at the > > device level rather than the stream level. > > > > > > > > > Thanks > > > Kaaira > > > > > >> > > >> Thanks, > > >> Dafna > > >> > > >> > > >>> > > >>> -- > > >>> Kieran > > >>> > > >>> > > >>> > > >>> > > >>>> Thanks, > > >>>> Dafna > > >>>> > > >>>>> > > >>>>> > > >>>>> I don't think that's a good example of the hardware though, as that > > >>>>> doesn't reflect what 'should' happen where the TPG runs once to generate > > >>>>> a frame at the sensor, which is then read by both the debayer entity and > > >>>>> the RAW capture device when there are two streams... > > >>>>> > > >>>>> > > >>>>> So I suspect trying to move to a single thread is desirable, but that > > >>>>> might be a fair bit of work also. > > >>>>> > > >>>>> -- > > >>>>> Kieran > > >>>>> > > >>>>> > > >>>>> > > >>>>>> The second capture that wants to stream should iterate the topology > > >>>>>> downwards until > > >>>>>> reaching an entity that already belong to the stream path of the other > > >>>>>> streaming capture > > >>>>>> and tell the streamer it wants to read the frames this entity > > >>>>>> produces. > > >>>>>> > > >>>>>> Thanks, > > >>>>>> Dafna > > >>>>>> > > >>>>>>> Thanks, > > >>>>>>> Dafna > > >>>>>>> > > >>>>>>>>>>>> > > >>>>>>>>>>>> I'm just curious if you are aware of this series? It would > > >>>>>>>>>>>> replace the > > >>>>>>>>>>>> need for 1/3 and 2/3 of this series right? > > >>>>>>>>>>> > > >>>>>>>>>>> v3 of this series replaces the need for 1/3, but not the current > > >>>>>>>>>>> version > > >>>>>>>>>>> (ie v4). v4 of patch 2/5 removes the stream_counter that is > > >>>>>>>>>>> needed to > > >>>>>>>>>>> keep count of the calls to s_stream. Hence 1/3 becomes relevant > > >>>>>>>>>>> again. > > >>>>>>>>>> > > >>>>>>>>>> So the question really is, how do we best make use of the two > > >>>>>>>>>> current > > >>>>>>>>>> series, to achieve our goal of supporting multiple streams. > > >>>>>>>>>> > > >>>>>>>>>> Having not parsed Dafna's series yet, do we need to combine > > >>>>>>>>>> elements of > > >>>>>>>>>> both ? Or should we work towards starting with this series and get > > >>>>>>>>>> dafna's patches built on top ? > > >>>>>>>>>> > > >>>>>>>>>> Or should patch 1/3 and 3/3 of this series be on top of Dafna's v4 ? > > >>>>>>>>>> > > >>>>>>>>>> (It might be noteworthy to say that Kaaira has reported successful > > >>>>>>>>>> multiple stream operation from /this/ series and her development > > >>>>>>>>>> branch > > >>>>>>>>>> on libcamera). > > >>>>>>>>> > > >>>>>>>>> Dafna's patch seems still under discussion, but I don't want to > > >>>>>>>>> block progress in Vimc either. > > >>>>>>>>> > > >>>>>>>>> So I was wondering if we can move forward with Vimc support for > > >>>>>>>>> multistreaming, > > >>>>>>>>> without considering Dafna's patchset, and we can do the clean up > > >>>>>>>>> later once we solve that. > > >>>>>>>>> > > >>>>>>>>> What do you think? > > >>>>>>>> > > >>>>>>>> I agree with supporting multiple streams with VIMC with this patchset, > > >>>>>>>> and then we can refactor the counters for s_stream in VIMC later (over > > >>>>>>>> this series) if dafna includes them in subsequent version of her > > >>>>>>>> patchset. > > >>>>>>>> > > >>>>>>> > > >>>>>>> I also think that adding support in the code will take much longer and > > >>>>>>> should not > > >>>>>>> stop us from supporting vimc independently. > > >>>>>>> > > >>>>>>> Thanks, > > >>>>>>> Dafna > > >>>>>>> > > >>>>>>>>> > > >>>>>>>>> Regards, > > >>>>>>>>> Helen > > >>>>>>>>> > > >>>>>>>>>> > > >>>>>>>>>> > > >>>>>>>>>>>> 1. > > >>>>>>>>>>>> https://lore.kernel.org/linux-media/20200522075522.6190-1-dafna.hirschfeld@xxxxxxxxxxxxx/ > > >>>>>>>>>>>> > > >>>>>>>>>>>> > > >>>>>>>>>>>> > > >>>>>>>>>>>>> > > >>>>>>>>>>>>> Changes since v1: > > >>>>>>>>>>>>> - All three patches rebased on latest media-tree. > > >>>>>>>>>>>>> Patch 3: > > >>>>>>>>>>>>> - Search for an entity with a non-NULL pipe instead of > > >>>>>>>>>>>>> searching > > >>>>>>>>>>>>> for sensor. This terminates the search at output itself. > > >>>>>>>>>>>>> > > >>>>>>>>>>>>> Kaaira Gupta (3): > > >>>>>>>>>>>>> media: vimc: Add usage count to subdevices > > >>>>>>>>>>>>> media: vimc: Serialize vimc_streamer_s_stream() > > >>>>>>>>>>>>> media: vimc: Join pipeline if one already exists > > >>>>>>>>>>>>> > > >>>>>>>>>>>>> .../media/test-drivers/vimc/vimc-capture.c | 35 > > >>>>>>>>>>>>> ++++++++++++++++++- > > >>>>>>>>>>>>> .../media/test-drivers/vimc/vimc-debayer.c | 8 +++++ > > >>>>>>>>>>>>> drivers/media/test-drivers/vimc/vimc-scaler.c | 8 +++++ > > >>>>>>>>>>>>> drivers/media/test-drivers/vimc/vimc-sensor.c | 9 ++++- > > >>>>>>>>>>>>> .../media/test-drivers/vimc/vimc-streamer.c | 23 > > >>>>>>>>>>>>> +++++++----- > > >>>>>>>>>>>>> 5 files changed, 73 insertions(+), 10 deletions(-) > > >>>>>>>>>>>>> > > >>>>>>>>>>>>> -- > > >>>>>>>>>>>>> 2.17.1 > > >>>>>>>>>>>>> > > >>>>>>>>>>>> > > >>>>>>>>>>>> -- > > >>>>>>>>>>>> Regards, > > >>>>>>>>>>>> Niklas Söderlund > > >>>>>>>>>> > > >>>>> > > >>> > > > > -- > > Regards > > -- > > Kieran
