[U-Boot-Users] Manual Setup of DDR2

[Jon Loeliger <jdl@jdl.com>]

[ Sorry to break the threading here.  --jdl ]

> * Without SPD EEPROM configured DDR, this must be setup manually.

You have two fundamental choices:

    - Use SPD on your DDR and hope that it gets the configuration right,

    - Turn SPD off, read the data sheets, derive memory controller values
      by hand, set them in the config file and hope they work.

My recommendation is to determine if the DDR2 you plan on using
will support SPD, and then let the SPD configuration take place.
It will be less work in the long run if it works.  Note that it
may _still_ take some tuning and parameter setting that is specific
to your board (and DDR).  There are values in this code that are
derived empirically, off a fast scope while looking at the data-eye
for some specific piece of DDR at a particular speed.  Your milage
will vary.  And if you don't pay attention here, you will hurt.
This is one of _the_ single largest U-Boot port failure cases!

Now, the 8548 reference board from Freescale had two type sof
memory on it.  One of which was on the local bus.  Depending on
your board, it may or may not have the second memory on it.
You may, or may not, need to set up different (additional) LAWs
and mappings for it.  IIRC, some of the memory is tacitly covered
by one Local bus LAW mapping?  Or may not even be mapped in at all.

You ask if "this" is the right approach, but I'm not really
sure what it is you are questioning....

The key is to do what is right for your board, of course.

jdl