[U-Boot-Users] pxa270 sdram address mapping

Konstantin Kletschke lists at ku-gbr.de
Tue Apr 11 12:06:03 CEST 2006


Hi Folks!

I am starting to design a new Hardware with a pxa270 processor with
sdram.
The processor family developer's manual introduces two address line
mappings from sdram controller to the sdram devices. One with MA<24:10>
and one alternative (MDCNFG[STACK]=0b01) with MA<24:23,13:1>.
The latter is required for use with pxa271 or pxa272 with internal RAM
or Flash devices. On the other hand I find no issue preventing me to use
this mapping also with pxa270 processor. Is this correct?

Is there speaking anything against alternative mapping in performance or
other disadvantages?
It is not clearly dissallowed to be used with pxa270 but not explicitely
allowed.

This alternative mapping allows me to use more different SDRAM devices,
since BA0 and BA1 are tied to MA<24:23> always. 

I only found lubbock.h usng this alternative mapping, but I don't know
which pxa27x processor it uses.

This question is intended to people which are used to pxa processors
since I am a pretty greenhorn with this arch.

Regards, Konsti

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