On 11/4/22 11:46, Hans Verkuil wrote: > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe > > Hi Laurent, > > On 22/06/2022 12:08, Laurent Pinchart wrote: >> Hi Hans, >> >> On Wed, Jun 22, 2022 at 12:00:58PM +0200, Hans Verkuil wrote: >>> On 22/06/2022 11:44, Laurent Pinchart wrote: >>>> 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 like polite and constructive disagreements, they help moving forward >> :-) >> >>>> 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. >> >> I have a few other things to complete first, an dI plan to resume the >> work in the first half of July, to post a v12 before the end of the >> month. > > Looking at the latest v15 series there are no conflicts with this patch. > > Eugen posted a v11 of his "atmel-isc: driver redesign" series, and wants > to use this functionality. > > I think with this change it is also possible to remove the enable_source > callback from the mc. I can try to post a v2 that does this, if that's > what it takes to convince you :-) Hello, The ISC driver looks more clean with these ops. I don't know how much it matters though. It's not a big improvement, rather small, but it looks cleaner. Thanks, Eugen > > 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(-) >> >
