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mitydsp L138 (OMAP) modify U-Boot to initialize video output and clock?

Helmut Forren
Mastermind 6805 points
Other Parts Discussed in Thread: CDCEL913

I have a standard mitydsp L138 (OMAP) SOM on my custom base board with ADV7391 video output chip and CDCEL913clock chip.  I am seeking to modify U-Boot in order to get internal color bars from the ADV7391 as quickly as possible for proof-of-life purposes.

How successful do you think I'll be in my modification efforts?  What snags do you think I might hit?  Do you have any additional suggestions.

Below is my current status and thoughts:

1) At the moment, I've found what is hopefully the source to the U-Boot I'm currently using, in the folder ~/MDK_2011-12-05/sw/ARM/u-boot-mitydspl138.  It doesn't recompile right off the bat, but hopefully I can get past that.  (Why oh why doesn't it ever...)  

2) Beyond that, I figure I need to do I2C access to configure the ADV7391 to produce it's color bars.  

3) It will need a clock input, which comes from the OMAP's CLKOUT2.  From a prior project where I used the kernel for proof-of-life, I'm pretty sure that clock won't be there already.  So I'll probably need to configure the OMAP hardware registers to map CLKIN2 to CLKOUT2, or possibly some other clkin.

4) Then, there's a probability that the CDCEL913 isn't configured yet either, to provide that CLKIN2 or other clkin.  That's another I2C access I'll need.

But putting all this together, I'm hoping to get color bars on my output within a couple seconds of power on.  (FYI I pursued super fast linux boot last time, and it wasn't a workable solution for me.)

Thanks in advance for your advice...

  • 0
    Prodigy 230 points

    Helmut,

    The u-boot you have in the MDK is likely a bit out of date. We provide a cloned git repository in the MDK which is now over a year old in your case. You should update your git repository by running "git pull" from the u-boot directory. There is a wiki page on our u-boot port on our support site (http://support.criticallink.com/redmine/projects/arm9-platforms/wiki/Das_U-Boot_Port)

    Depending on which i2c bas you have the ADV7391 on, you may have to reconfigure the pin-mux settings of the OMAP. u-boot does not set up all the pin muxing, only the pins it needs to do its job. You can modify the pin mux registers using the mw.w command from the u-boot shell or, obviously, in code. The same goes for the CLKOUT2 signal.

    If you can get the ADV7391 to generate a test pattern just from i2c commands, then I'd suggest scripting it from the u-boot shell (or writing and compiling a u-boot script if it is more involved).

    Hope this gets you at least going in the write direction...

    cheers

    /Tim