[U-Boot-Users] u-boot 834x spd_ram

Ben Warren bwarren at qstreams.com
Tue Apr 18 16:07:35 CEST 2006


Jerry,

The 83xx chips have a separate memory bus for DDR, with its own chip
selects.  For these chips, you do in fact need to use the local bus CS0
for your boot flash/EEPROM.

I can't find anything in the manual that differentiates between the DDR
chip selects, so using CS2/3 was probably just a design choice.

regards,
Ben

On Tue, 2006-04-18 at 10:02 -0400, Jerry Van Baren wrote:

> Aziz Mzili wrote:
> > 
> > Hi
> > 
> > I'm wondering why in cpu/83xx/spd_ram.c we expect the DDR ram to be on 
> > cs2 and cs3. Is there any issue with it on cs0 and cs1 ?
> > 
> > thank you
> > 
> > Aziz Mzili
> 
> I'm not a 834x expert, but all my experience is that CS0 is used to boot 
> the processor.  If it is DDR RAM rather than flash, someone other than 
> the 834x must initialize the DDR RAM and load it with the boot program. 
>   That is possible, but very uncommon.
> 
> gvb
> 
> 
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