On 2011-08-29 04:49, Laurent Pinchart wrote:
Hi Gary,
On Thursday 25 August 2011 18:07:38 Gary Thomas wrote:
Background: I have working video capture drivers based on the
TI PSP codebase from 2.6.32. In particular, I managed to get
a driver for the TVP5150 (analogue BT656) working with that kernel.
Now I need to update to Linux 3.0, so I'm trying to get a driver
working with the rewritten ISP code. Sadly, I'm having a hard
time with this - probably just missing something basic.
I've tried to clone the TVP514x driver which says that it works
with the OMAP3 ISP code. I've updated it to use my decoder device,
but I can't even seem to get into that code from user land.
Here are the problems I've had so far:
* udev doesn't create any video devices although they have been
registered. I see a full set in /sys/class/video4linux
# ls /sys/class/video4linux/
v4l-subdev0 v4l-subdev3 v4l-subdev6 video1 video4
v4l-subdev1 v4l-subdev4 v4l-subdev7 video2 video5
v4l-subdev2 v4l-subdev5 video0 video3 video6
It looks like a udev issue. I don't think that's related to the kernel
drivers.
Indeed, if I create /dev/videoX by hand, I can get somewhere, but
I don't really understand how this is supposed to work. e.g.
# v4l2-dbg --info /dev/video3
Driver info:
Driver name : ispvideo
Card type : OMAP3 ISP CCP2 input
Bus info : media
Driver version: 1
Capabilities : 0x04000002
Video Output
Streaming
* If I try to grab video, the ISP layer gets a ton of warnings, but
I never see it call down into my driver, e.g. to check the current
format, etc. I have some of my own code from before which fails
miserably (not a big surprise given the hack level of those programs).
I tried something off-the-shelf which also fails pretty bad:
# ffmpeg -t 10 -f video4linux2 -s 720x480 -r 30 -i /dev/video2
junk.mp4
I've read through Documentation/video4linux/omap3isp.txt without learning
much about what might be wrong.
Can someone give me some ideas/guidance, please?
In a nutshell, you will first have to configure the OMAP3 ISP pipeline, and
then capture video.
Configuring the pipeline is done through the media controller API and the V4L2
subdev pad-level API. To experiment with those you can use the media-ctl
command line application available at http://git.ideasonboard.org/?p=media-
ctl.git;a=summary. You can run it with --print-dot and pipe the result to dot
-Tps to get a postscript graphical view of your device.
Here's a sample pipeline configuration to capture scaled-down YUV data from a
sensor:
./media-ctl -r -l '"mt9t001 3-005d":0->"OMAP3 ISP CCDC":0[1], "OMAP3 ISP
CCDC":2->"OMAP3 ISP preview":0[1], "OMAP3 ISP preview":1->"OMAP3 ISP
resizer":0[1], "OMAP3 ISP resizer":1->"OMAP3 ISP resizer output":0[1]'
./media-ctl -f '"mt9t001 3-005d":0[SGRBG10 1024x768], "OMAP3 ISP
CCDC":2[SGRBG10 1024x767], "OMAP3 ISP preview":1[YUYV 1006x759], "OMAP3 ISP
resizer":1[YUYV 800x600]'
After configuring your pipeline you will be able to capture video using the
V4L2 API on the device node at the output of the pipeline.
Getting somewhere now, thanks. When I use this full pipeline, I can get all
the way into my driver where it's trying to start the data.
What if I want to use less of the pipeline? For example, I'd normally be
happy with just the CCDC output. How would I do that? What pixel format
would I use with ffmpeg?
n.b. I know most of these are pretty n00b questions - I'd look up the
answers for myself, but I've had precious little success finding any
documentation, especially on media-ctl and/or the OMAP3 ISP setups.
Thanks again
--
------------------------------------------------------------
Gary Thomas | Consulting for the
MLB Associates | Embedded world
------------------------------------------------------------
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