Re: Getting started with OMAP3 ISP

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

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 ? :-)

-- 
Regards,

Laurent Pinchart