Le vendredi 31 mai 2019 à 11:01 +0300, Stanimir Varbanov a écrit : > 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. And to add to this, CODA driver is special, since it has a third buffer queue, the queue expose on the CAPTURE device does not need to be representative of the DPB depth. > > So, just to confirm - you are fine with blocking G_FMT (not REQBUF) when > the user doesn't subscribe for v4l2 events? > > > > > Another question: If we intend this to be implemented in new drivers > > > > too, should it be documented in the spec? > > > > > > We most certainly do NOT want to implement this in new drivers. > > > > > > > Makes sense. > > > > When venus was merged initially, did it already have a blocking G_FMT? > > No it isn't. >
Attachment:
signature.asc
Description: This is a digitally signed message part
