Hi Michael, On Wednesday 07 December 2011 12:01:17 Michael Jones wrote: > On 12/07/2011 11:34 AM, Laurent Pinchart wrote: > > On Wednesday 07 December 2011 09:02:42 Adam Pledger wrote: > >> Hi Laurent, > >> > >> Firstly, please accept my apologies, for what is very probably a naive > >> question. I'm new to V4L2 and am just getting to grips with how things > >> work. > > > > No worries. > > > >> I'm using a tvp5151 in bt656 mode with the Omap3 ISP, > > > > Please note that BT.656 support is still experimental, so issues are not > > unexpected. > > > >> as described in this thread (Your YUV support tree + some patches for > >> bt656, based on 2.6.39): > >> http://comments.gmane.org/gmane.linux.drivers.video-input- > > > > infrastructure/39539 > > > >> I am able to capture some frames using yavta, using the media-ctl > >> configuration as follows: > >> media-ctl -v -r -l '"tvp5150 3-005d":0->"OMAP3 ISP CCDC":0[1], "OMAP3 > >> ISP CCDC":1->"OMAP3 ISP CCDC output":0[1]' > >> media-ctl -v --set-format '"tvp5150 3-005d":0 [UYVY2X8 720x625]' > >> media-ctl -v --set-format '"OMAP3 ISP CCDC":0 [UYVY2X8 720x625]' > >> media-ctl -v --set-format '"OMAP3 ISP CCDC":1 [UYVY2X8 720x625]' > > > >> This yields this: > > [snip] > > > > Looks good. > > > >> The following works nicely: > >> yavta -f UYVY -s 720x625 -n 4 --capture=4 -F /dev/video2 > >> > >> The problem comes when I try to use gstreamer to capture from > >> /dev/video2, using the following: > >> gst-launch v4l2src device="/dev/video2" ! > >> 'video/x-raw-yuv,width=720,height=625' ! filesink location=sample.yuv > >> > >> This fails with: > >> ERROR: from element /GstPipeline:pipeline0/GstV4l2Src:v4l2src0: Failed > >> getting controls attributes on device '/dev/video2'. > >> Additional debug info: > >> v4l2_calls.c(267): gst_v4l2_fill_lists (): > >> /GstPipeline:pipeline0/GstV4l2Src:v4l2src0: > >> Failed querying control 9963776 on device '/dev/video2'. (25 - > >> Inappropriate ioctl for device) > >> > >> My question is, should this "just work"? It was my understanding that > >> once the pipeline was configured with media-ctl then the CCDC output pad > >> should behave like a standard V4L2 device node. > > > > That's more or less correct. There have been a passionate debate > > regarding what a "standard V4L2 device node" is. Not all V4L2 ioctls are > > mandatory, and no driver implements them all. The OMAP3 ISP driver > > implements a very small subset of the V4L2 API, and it wasn't clear > > whether that still qualified as V4L2. After discussions we decided that > > the V4L2 specification will document profiles, with a set of required > > ioctls for each of them. The OMAP3 ISP implements the future video > > streaming profile. > > > > I'm not sure what ioctls v4l2src consider as mandatory. The above error > > related to a CTRL ioctl (possibly VIDIOC_QUERYCTRL), which isn't > > implemented by the OMAP3 ISP driver and will likely never be. I don't > > think that should be considered as mandatory. > > > > I think that v4l2src requires the VIDIOC_ENUMFMT ioctl, which isn't > > implemented in the OMAP3 ISP driver. That might change in the future, but > > I'm not sure yet whether it will. In any case, you might have to modify > > v4l2src and/or the OMAP3 ISP driver for now. Some patches have been > > posted a while ago to this mailing list. > > Here was my submission for ENUM_FMT support: > http://www.mail-archive.com/linux-media@xxxxxxxxxxxxxxx/msg29640.html > > I submitted this in order to be able to use the omap3-isp with > GStreamer. I missed the discussion about V4L2 "profiles", but when I > submitted that patch we discussed whether ENUM_FMT was mandatory. After > I pointed out that the V4L2 spec states plainly that it _is_ mandatory, > I thought Laurent basically agreed that it was reasonable. > > Laurent, what do you think about adding ENUM_FMT support now? I'm OK with it, but we need to discuss the details. During the latest V4L2 meeting in Prague we decided to create a "streaming" profile for V4L2 device nodes such as the ones created by the OMAP3 ISP driver. We now need to decide which ioctls will be mandatory in that profile (ENUM_FMT will likely be), and what they should return exactly. That's on my to-do list (but handling my e- mail backlog comes first :-)). > >> I realise that this might be something borked with my build dependencies > >> (although I'm pretty certain that v4l2src is being built against the > >> latest libv42) or gstreamer. Before I start digging through the code to > >> work out what is going on with the ioctl handling, I thought I would > >> check to see whether this should work, or whether I am doing something > >> fundamentally silly. -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
