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. 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). What can be a better design for VIMC to have a single thread if two streams are asked (apart/of the options I mentioned)? 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 > > > > > > > > > > > > > > >
