OMAP3 DSS2 - VENC timings

OMAP3 DSS2 - VENC timings

[Gary Thomas]

I'm running a frame buffer console on a TV device via the VENC.
The video timings don't see to be quite right as Tux is about
1/2 off the screen - both directions, i.e. his head and right
side have been cut off as they are outside the viewable area.
Also, when I send data to the device (via /dev/tty1) which has
90x35 characters, I lose 4 characters on each end of every line.

Is there something I can do about this?  I've looked at the
timings in drivers/video/omap2/dss/venc.c

Also, how can I select NTSC vs PAL setups via the command line?
I have only the one video device VENC.

Thanks

-- 
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Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world
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Re: OMAP3 DSS2 - VENC timings

[Tomi Valkeinen]

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On Mon, 2012-01-16 at 11:08 -0700, Gary Thomas wrote:
> I'm running a frame buffer console on a TV device via the VENC.
> The video timings don't see to be quite right as Tux is about
> 1/2 off the screen - both directions, i.e. his head and right
> side have been cut off as they are outside the viewable area.
> Also, when I send data to the device (via /dev/tty1) which has
> 90x35 characters, I lose 4 characters on each end of every line.
> 
> Is there something I can do about this?  I've looked at the
> timings in drivers/video/omap2/dss/venc.c

I don't know much about analog TV, but my understanding is that there's
always overscanning going on. You just have to size and position the
overlay so that it is visible on your TV.

> Also, how can I select NTSC vs PAL setups via the command line?
> I have only the one video device VENC.

Documentation/arm/OMAP/DSS says you can echo "pal" or "ntsc" to
sys/devices/platform/omapdss/display?/timings file.

 Tomi


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RE: OMAP3 DSS2 - VENC timings

[Hiremath, Vaibhav]

On Wed, Jan 18, 2012 at 13:08:23, Valkeinen, Tomi wrote:
> On Mon, 2012-01-16 at 11:08 -0700, Gary Thomas wrote:
> > I'm running a frame buffer console on a TV device via the VENC.
> > The video timings don't see to be quite right as Tux is about
> > 1/2 off the screen - both directions, i.e. his head and right
> > side have been cut off as they are outside the viewable area.
> > Also, when I send data to the device (via /dev/tty1) which has
> > 90x35 characters, I lose 4 characters on each end of every line.
> > 

I am not sure whether this applies here with your issue, but if I remember
correctly, during initial days of development we had similar issue where, corners of the display cuts-off. The conclusion was, analog TV's crops the ~5-10% of the input image (depends on TV). I don't quite remember further details on this...


Thanks,
Vaibhav

> > Is there something I can do about this?  I've looked at the
> > timings in drivers/video/omap2/dss/venc.c
> 
> I don't know much about analog TV, but my understanding is that there's
> always overscanning going on. You just have to size and position the
> overlay so that it is visible on your TV.
> 
> > Also, how can I select NTSC vs PAL setups via the command line?
> > I have only the one video device VENC.
> 
> Documentation/arm/OMAP/DSS says you can echo "pal" or "ntsc" to
> sys/devices/platform/omapdss/display?/timings file.
> 
>  Tomi
> 
>