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...