Disabling video in u-boot / 3.3v supply

Hello,

I've modified my Beagle Board to access the 3.3v power rail from the
TPS2141 via TP3. If I attach say ~50 ohms load to this rail the board
fails to power on - only D5 lights up and I only get 2v on the 3.3v
rail. I'm not using video at all and my kernel is configured with
GPIO170 not asserted, so the TFP410 is disabled If I attach my load
once the kernel has booted I can draw 100ma without any problems and I
get close to 3.3v. The problem looks to be u-boot enabling the video.
If I look at board/omap3/beagle/beagle.c in u-boot I can see GPIO 170
is set to pull up. I can set this to pull down but I'm worried this
will end up bricking my board due to other things in u-boot which
expect the TFP410 being powered on. I've had a bit of a poke around
the source and can't work out what video driver the beagleboard used.
Does anyone out there have any suggestions?

Thanks,

Christopher.

The problem looks to be u-boot enabling the video.
If I look at board/omap3/beagle/beagle.c in u-boot I can see GPIO 170
is set to pull up. I can set this to pull down but I'm worried this
will end up bricking my board due to other things in u-boot which
expect the TFP410 being powered on. I've had a bit of a poke around
the source and can't work out what video driver the beagleboard used.
Does anyone out there have any suggestions?

Hi Christopher,

All "communication" from the OMAP to TFP410 is unidirectional - Uboot will
therefore not be able to tell if you remove the code enabling the TFP410
chip.

Even in the unlikely case that Uboot would break down (due to some other
reason), you will still be able to recover the board by use of peripheral
booting as described in: http://elinux.org/BeagleBoardRecovery

Sendonly in case you have a newer xloader (can't remember which version
needed) in the board NAND you can experiment with uboot located on a MMC
card for easy development and removal in case something fails...

Best regards - Good luck
  Søren