[U-Boot-Users] yet another how-to-configure-RAM-in-u-boot question

[U-Boot-Users] yet another how-to-configure-RAM-in-u-boot question

[Peter Asemann]

Hi there!

I'm having quite a few problems of understanding while trying to write 
an U-Boot configuration for my board.

I've read in the mailing list archives and in the README... as you see, 
it didn't help much.

The README says (I had the impression) that the following happens when 
the U-Boot starts:

U-Boot maps memory banks using the preliminary mapping, tests RAM sizes, 
then banks of the same are mapped from 0x0 on, starting with CS#2.

So my first question is: Am I in trouble for my SDRAM bank actually is 
at CS #1? This seems to be what U-Boot expects, everything in the README 
reads like no SDRAM should be at a bank below CS#2.

Peter Asemann

[U-Boot-Users] yet another how-to-configure-RAM-in-u-boot question

[Wolfgang Denk]

Hello,

in message <429B5AAE.2050002@web.de> you wrote:
> 
> U-Boot maps memory banks using the preliminary mapping, tests RAM sizes, 
> then banks of the same are mapped from 0x0 on, starting with CS#2.

For completeness: the mapping starts at 0x0000 on PowerPC only; other
architectures use other memory maps.

> So my first question is: Am I in trouble for my SDRAM bank actually is 
> at CS #1? This seems to be what U-Boot expects, everything in the README 
> reads like no SDRAM should be at a bank below CS#2.

No, there is no such assumption - it is up to your hardware  (and  to
your code which supports your hardare) which chip select(s) are used.
The  description  in the README is just an example that shows what to
do in case of more than one flash bank and more than one RAM bank.

If you have only one bank of  flash  memopry  (at  CS0)  then  it  is
perfectly fine to use CS1 for RAM.

Best regards,

Wolfgang Denk

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