Re: Getting started with OMAP3 ISP

[Gary Thomas <gary@mlbassoc.com>]

On 2011-08-30 08:20, Laurent Pinchart wrote:
> Hi Gary,
>
> On Tuesday 30 August 2011 16:18:00 Gary Thomas wrote:
>> On 2011-08-30 08:08, 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.
>>>
>>> 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?
>
> It could be. You need the /dev/video* and /dev/v4l-subdev* device nodes.

Yes, that helped a lot.  When I create the devices by hand, I can now see
my driver starting to be accessed (right now it's very much an empty stub)

Any ideas why udev (version 164) is not making these nodes automatically?

>
>> 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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