[U-Boot] Possible Denx m28evk ethernet problem + solution

[Marek Vasut <marek.vasut@gmail.com>]

> > Please use Stefano's imx git tree, which has support for mx28evk already.
> 
> Thanks for the heads-up. It's a bit confusing and unexpected to have a
> mainline spread across different git trees; Will Stefano's mainline be
> integrated into the main-mainline sometime?

Not really ... that's how it all works. When Stefano sends pull RQ, it'll go 
mainline.
> 
> > m28evk and mx28evk differ in the way they driver their Ethernet PHYs.
> 
> Yes, Marek has patiently explained that to me; It's all clear now. But it
> was a good exercise because our product board has a different phy too.
> 
> > Let me know if you have any issues.
> 
> I have a question: The auto-detected SDRAM size is parsed form SPL to
> U-Boot through both scrathch1 and scratch2, probably as a safeguard not to
> assume any value to be a valid one. Did you ever see the error or
> different scratch values occur? I never did. But what I do see occur every
> now and then is a value of 0 in both registers, mostly after obscure reset
> scenarios.

I see no problems with the board DRAM detection on our board, no. I tested this 
quite thoroughly.

I don't see the registers differ either ... ever. I suspect your problem is with 
your DRAM configuration data -- if your DRAM chip is misconfigured, you'll get 
such memory problems.

> 
> Can we agree on a different algo to determine the validity of SDRAM size?
> I'm thinking somewhere around the line of a power of 2 between 2MiB and
> 1GiB. Preferable I'd like to use only 1 scratch register for that. The
> other scratch register could then be used to store the boot-mode value
> during SPL stage. The boot mode value is useful for boards capable of
> booting from different MMC devices, like ours.

RFC/patch is always welcome.
> 
> BTW: My version has both MMCs, both Ethernet intefaces and NAND working for
> the evk.

MX28EVK has no NAND if I understand it correctly.

> I have also typed in regs-digctl.h. I can send you or Stefano my
> files, if they're any use to you.

Make a patch and submit to the mailing list, like everyone else does please. 
Don't try to reinvent wheel ... square one this time even.
> 
> Cheers,
> 
>          Robert.

M