Re: Getting started with OMAP3 ISP

[Gary Thomas <gary@mlbassoc.com>]

On 2011-08-30 08:08, Gary Thomas wrote:
> 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.
>
> Thanks for the info.
>
> When I run 'media-ctl -p', I see the various nodes, etc, and they all look
> good except that I get lots of messages like this:
> - entity 5: OMAP3 ISP CCDC (3 pads, 9 links)
> type V4L2 subdev subtype Unknown
> pad0: Input v4l2_subdev_open: Failed to open subdev device node

Could this be related to my missing [udev] device nodes?

I can see media-ctl get confused and try to open a nonsense device name.  Here's
what I see when I run
   # strace media-ctl -p | grep open
   open("/dev/media0", O_RDWR)             = 3
   open("", O_RDWR)                        = -1 ENOENT (No such file or directory)
   write(1, "\tpad0: Input v4l2_subdev_open: F"..., 66) = 66

>
> When I try to setup my pipeline using something similar to what you provided, the
> first step runs and I can see that it does something (some lines on the graph went
> from dotted to solid), but I still get errors:
> # media-ctl -r -l '"tvp5150m1 2-005c":0->"OMAP3 ISP CCDC":0[1], "OMAP3 ISP CCDC":1->"OMAP3 ISP CCDC output":0[1]'
> Resetting all links to inactive
> Setting up link 16:0 -> 5:0 [1]
> Setting up link 5:1 -> 6:0 [1]
> # media-ctl -f '"tvp5150m1 2-005c":0[SGRBG12 320x240], "OMAP3 ISP CCDC":0[SGRBG8 320x240], "OMAP3 ISP CCDC":1[SGRBG8 320x240]'
> Setting up format SGRBG12 320x240 on pad tvp5150m1 2-005c/0
> v4l2_subdev_open: Failed to open subdev device node
> Unable to set format: No such file or directory (-2)
>
> As far as I can tell, none if this is making any callbacks into my driver.
>
> Any ideas what I might be missing?
>
> Thanks
>

-- 
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Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world
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