On Mon, Jun 3, 2019 at 4:26 PM Hans Verkuil <hverkuil@xxxxxxxxx> wrote: > > On 5/31/19 10:01 AM, Stanimir Varbanov wrote: > > Hi, > > > > On 5/27/19 11:18 AM, Tomasz Figa wrote: > >> On Mon, May 27, 2019 at 4:39 PM Hans Verkuil <hverkuil@xxxxxxxxx> wrote: > >>> > >>> On 5/27/19 5:51 AM, Tomasz Figa wrote: > >>>> On Tue, May 21, 2019 at 9:27 PM Hans Verkuil <hverkuil@xxxxxxxxx> wrote: > >>>>> > >>>>> On 5/21/19 11:09 AM, Tomasz Figa wrote: > >>>>>> Hi Stan, > >>>>>> > >>>>>> On Mon, May 20, 2019 at 11:47 PM Stanimir Varbanov > >>>>>> <stanimir.varbanov@xxxxxxxxxx> wrote: > >>>>>>> > >>>>>>> Hi Tomasz, > >>>>>>> > >>>>>>> On 4/24/19 3:39 PM, Tomasz Figa wrote: > >>>>>>>> On Wed, Apr 24, 2019 at 9:15 PM Stanimir Varbanov > >>>>>>>> <stanimir.varbanov@xxxxxxxxxx> wrote: > >>>>>>>>> > >>>>>>>>> Hi Hans, > >>>>>>>>> > >>>>>>>>> On 2/15/19 3:44 PM, Hans Verkuil wrote: > >>>>>>>>>> Hi Stanimir, > >>>>>>>>>> > >>>>>>>>>> I never paid much attention to this patch series since others were busy > >>>>>>>>>> discussing it and I had a lot of other things on my plate, but then I heard > >>>>>>>>>> that this patch made G_FMT blocking. > >>>>>>>>> > >>>>>>>>> OK, another option could be to block REQBUF(CAPTURE) until event from hw > >>>>>>>>> is received that the stream is parsed and the resolution is correctly > >>>>>>>>> set by application. Just to note that I'd think to this like a temporal > >>>>>>>>> solution until gstreamer implements v4l events. > >>>>>>>>> > >>>>>>>>> Is that looks good to you? > >>>>>>>> > >>>>>>>> Hmm, I thought we concluded that gstreamer sets the width and height > >>>>>>>> in OUTPUT queue before querying the CAPTURE queue and so making the > >>>>>>>> driver calculate the CAPTURE format based on what's set on OUTPUT > >>>>>>>> would work fine. Did I miss something? > >>>>>>> > >>>>>>> Nobody is miss something. > >>>>>>> > >>>>>>> First some background about how Venus implements stateful codec API. > >>>>>>> > >>>>>>> The Venus firmware can generate two events "sufficient" and > >>>>>>> "insufficient" buffer requirements (this includes decoder output buffer > >>>>>>> size and internal/scratch buffer sizes). Presently I always set minimum > >>>>>>> possible decoder resolution no matter what the user said, and by that > >>>>>>> way I'm sure that "insufficient" event will always be triggered by the > >>>>>>> firmware (the other reason to take this path is because this is the > >>>>>>> least-common-divider for all supported Venus hw/fw versions thus common > >>>>>>> code in the driver). The reconfiguration (during codec Initialization > >>>>>>> sequence) is made from STREAMON(CAPTURE) context. Now, to make that > >>>>>>> re-configuration happen I need to wait for "insufficient" event from > >>>>>>> firmware in order to know the real coded resolution. > >>>>>>> > >>>>>>> In the case of gstreamer where v4l2_events support is missing I have to > >>>>>>> block (wait for firmware event) REQBUF(CAPTURE) (vb2::queue_setup) or > >>>>>>> STREAMON(CAPTURE) (vb2::start_streaming). > >>>>>>> > >>>>>>> I tried to set the coded resolution to the firmware as-is it set by > >>>>>>> gstreamer but then I cannot receive the "sufficient" event for VP8 and > >>>>>>> VP9 codecs. So I return back to the solution with minimum resolution above. > >>>>>>> > >>>>>>> I'm open for suggestions. > >>>>>> > >>>>>> I think you could still keep setting the minimum size and wait for the > >>>>>> "insufficient" event. At the same time, you could speculatively > >>>>>> advertise the expected "sufficient" size on the CAPTURE queue before > >>>>>> the hardware signals those. Even if you mispredict them, you'll get > >>>>>> the event, update the CAPTURE resolution and send the source change > >>>>>> event to the application, which would then give you the correct > >>>>>> buffers. Would that work for you? > >>>>> > >>>>> As I understand it this still would require event support, which gstreamer > >>>>> doesn't have. > >>>> > >>>> I don't think it matches what I remember from the earlier discussion. > >>>> As long as Gstreamer sets the visible resolution (from the container > >>>> AFAIR) on OUTPUT, the driver would adjust it to something that is > >>>> expected to be the right framebuffer resolution and so Gstreamer would > >>>> be able to continue. Of course if the expected value doesn't match, it > >>>> wouldn't work, but it's the same as currently for Coda AFAICT. > >>>> > >>>>> > >>>>> I think it is OK to have REQBUFS sleep in this case. However, I would only > >>>> > >>>> Why REQBUFS? While that could possibly allow us to allocate the right > >>>> buffers, Gstreamer wouldn't be able to know the right format, because > >>>> it would query it before REQBUFS, wouldn't it? > >>> > >>> Oops, you are right. It's got to be in G_FMT(CAPTURE), but *only* if > >>> nobody subscribed to the SOURCE_CHANGE event. > >>> > >>>> > >>>> For this reason, s5p-mfc makes G_FMT(CAPTURE) blocking and if we > >>>> decide to forcefully keep the compatibility, even with in drivers, we > >>>> should probably do the same here. > >>>> > >>>>> enable this behavior if the application didn't subscribe to the SOURCE_CHANGE > >>>>> event. That's easy enough to check in the driver. And that means that if the > >>>>> application is well written, then the driver will behave in a completely > >>>>> standard way that the compliance test can check. > >>>> > >>>> I guess one could have some helpers for this. They would listen to the > >>>> source change events internally and block / wake-up appropriate ioctls > >>>> whenever necessary. > >>> > >>> I really do not want this for new drivers. gstreamer should be fixed. > >>> A blocking G_FMT is just plain bad. Only those drivers that do this, can > >>> still block if nobody subscribed to EVENT_SOURCE_CHANGE. > >> > >> Yeah and that's why I just suggested to mimic coda, which doesn't > >> block, but apparently gstreamer still works with it. > > > > Unfortunately in Venus case that is not an easy task (as I tried to > > explain why above). > > > > To have an unified and common code for all different SoCs and > > firmware/hardware versions I decided to set the minimum supported > > resolution for the decoder (no matter what the user said) and trigger > > the reconfiguration event always. Something more, I need the event also > > to retrieve the minimum capture buffers > > (V4L2_CID_MIN_BUFFERS_FOR_CAPTURE) and sizes for capture and > > internal/scratch buffers as well, thus I really need to wait for that > > event. > > > > So, just to confirm - you are fine with blocking G_FMT (not REQBUF) when > > the user doesn't subscribe for v4l2 events? > > 'Fine' is too strong a word :-) > > But I think this is a reasonable compromise. > > Document carefully why you are doing this, since it is purely for backwards > compatibility reasons. And perhaps at some point in the future the workaround > might be removed again. Thanks Hans. I don't have objections either. Best regards, Tomasz
