Re: Getting started with OMAP3 ISP

[Gary Thomas <gary@mlbassoc.com>]

On 2011-08-31 02:13, Laurent Pinchart wrote:
> Hi Gary,
>
> On Wednesday 31 August 2011 02:07:36 Gary Thomas wrote:
>> On 2011-08-30 16:50, Laurent Pinchart wrote:
>>> On Wednesday 31 August 2011 00:45:39 Gary Thomas wrote:
>>>> On 2011-08-29 04:49, Laurent Pinchart wrote:
>>>>> 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?
>>>
>>> Then connect CCDC's pad 1 to the CCDC output video node and capture on
>>> that video node.
>>>
>>>> What pixel format would I use with ffmpeg?
>>>
>>> What does your subdev deliver ?
>>
>> It's a BT656 encoder - 8-bit UYVY 4:2:2
>
> Then you will first have to add YUV support to the CCDC. It wouldn't be fun if
> it worked out of the box, would it ? :-)

So, functionality that was present in 2.6.32 (TI PSP version at least)
is not currently available?

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