Re: mt9p031 shows purple coloured capture

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

Hi Florian,

On Tuesday 11 June 2013 10:01:31 Florian Neuhaus wrote:
> Hi Andrei,
> 
> Your post helped me a lot!
> My environment:
> beagleboard-xm
> mt9p031 @96Mhz (adapted power-supply)
> linux-omap 3.7.10
> omap3isp-live
> 
> I have two similiar issues with the mt9p031, that has probably the same
> cause:
> 
> If I use omap3isp-live to capture a stream on my beagleboard, the first time
> I start the app, the picture has always a green taint. The second time I
> start the app, the picture is good. As the camera is reset by a gpio upon
> device open, probably the CCDC or previewer is not initialized correctly?
> @Laurent: As I am unable to test it with another cam, does this also happen
> with your hardware or is it a problem specific to the mt9p031?

Last time I've tested my MT9P031 sensor with the Beagleboard-xM there was no 
such issue.

> The second problem is similiar to your problem:
> omap3isp-live has (thanks to Laurent) a built in snapshot-mode. So I am
> doing the following:
> 1. Streaming video, picture looks good on the second start
> 2. Taking a snapshot: The video stream will turn off, the isp-pipe
> reconfigured. Then the stream will be turned back on and the captured image
> will be written to memory.
> 3. The captured image will now be displayed, but the image is corrupted:
> Wrong colors and cut in half:
> https://www.dropbox.com/s/ijk1nq8nrhlobfd/bad-snapshot.jpg
> 4. It doesn't help to skip a few buffers, also the 3rd buffer looks bad.
> 5. Additional problem: The CCDC can't be stopped properly (omap3isp
> omap3isp: Unable to stop OMAP3 ISP CCDC) and sometimes the isp locks up
> completely.
>
> > So I used the register 0x0B (Restart), bit 0 (abandon the current frame
> > and restart from the first row) set to 1 each time the function s_stream
> > is called.
>
> The finding so far: If I do a frame-restart (the register 0x0b on mt9p031)
> upon stream-on, the CCDC can be stopped properly and the snapshot looks
> pretty good. BUT the colors are still messed up. If I then switch to
> streaming again, the colors sometimes turn to good but sometimes the picture
> is purple tainted. @Andrei: What have you done to get good colors?
> 
> >> Wrong clock or *sync polarity selection? Which leads to random
> >> start-of-frame misplacement?
> > 
> > Do you mean pixel clock polarity? If so, I checked it - with it being
> > inverted - the image capture goes well (purple color also appears from
> > time to time), but in the case it is not inverted I see a noise on the
> > screen.
> 
> Inverted the pixel-clock on the mt9p031 side (register 0x0a, bit 15)? I
> inverted the clock, but then the streaming had a purple taint.

-- 
Regards,

Laurent Pinchart