Hi Laurent, On 22/06/2022 11:44, Laurent Pinchart wrote: > Hi Hans, > > On Wed, Jun 22, 2022 at 11:31:43AM +0200, Hans Verkuil wrote: >> Add support for two new (un)prepare_streaming queue ops that are called >> when the user calls VIDIOC_STREAMON and STREAMOFF (or closes the fh). >> >> This gives drivers a callback to validate the video pipeline and claim >> or release streaming resources at the time that userspace indicates >> that it wants to start streaming (VIDIOC_STREAMON) rather than when >> the actual DMA engine kicks in (the start_streaming callback). This >> is relevant for drivers that needs a minimum of X buffers before the >> DMA can start. The actual pipeline validation needs to happen sooner >> to avoid unnecessary errors at VIDIOC_QBUF time. >> >> As a bonus this allows us to move the horrible call to >> v4l_vb2q_enable_media_source() in vb2_core_streamon() to the au0828 >> driver (currently the only driver that uses this feature). > > Can we drop the horrible .enable_source() from media_device too ? :-) The second patch helps a bit with that, at least it's out of vb2. > >> That call never belonged in vb2, but it had the same purpose as the >> new prepare_streaming op: validate the pipeline. >> >> This is a follow-up from my previous RFCv2: >> >> https://patchwork.linuxtv.org/project/linux-media/patch/ba4bca14-488f-94ea-48d9-e7343103c5aa@xxxxxxxxx/ >> >> I would like to get consensus for this series. > > I don't like it much. vb2 is already doing too much in my opinion, > growing it isn't the right way to fix it. We disagree on that :-) > > I'm still working on a new version of the V4L2 streams series that may > conflict with this, I'd propose discussing the two together. What is the ETA for that? I don't mind waiting a few months, but if it takes a lot longer, then I'd rather merge this first so Eugen can use it in his atmel MC support. It's a kernel API, so it can always be changed or removed later. Regards, Hans > >> Hans Verkuil (2): >> vb2: add (un)prepare_streaming queue ops >> vb2/au0828: move the v4l_vb2q_enable_media_source to the au0828 driver >> >> .../media/common/videobuf2/videobuf2-core.c | 26 ++++++++++++++----- >> drivers/media/usb/au0828/au0828-vbi.c | 2 ++ >> drivers/media/usb/au0828/au0828-video.c | 1 + >> include/media/videobuf2-core.h | 14 ++++++++++ >> 4 files changed, 37 insertions(+), 6 deletions(-) >
