[U-Boot] How do ARM platform initialize DDR?

[Wolfgang Denk]

Dear Timur,

In message <CAOZdJXVDf7Z7Ya8p4nkybp1wJ1cnMTs736cEtRNp_9yQYgQ68A at mail.gmail.com> you wrote:
> On Tue, Sep 17, 2013 at 10:59 AM, York Sun <yorksun at freescale.com> wrote:
> > I am wondering if there is generic
> > DDR driver used by many ARM platforms, like the one we have for
> > powerpc/mpc85xx SoCs.
> 
> Sadly, no such thing exists.  There is no generic DDR controller for
> ARM.  I'm working on DDR controller support for our ARM chips, and
> it's nowhere near as elegant as Freescale's PowerPC parts.  In our

MPC85xx is just one family of processors.  And I don't think you
really want to claim that all Freescale's PowerPC processors use the
same memory controller?  Try and compare the memory controllers (and
the required initialization sequences) for just a selection of
MPC8xx, MPC82xx, MPC83xx, MPC85xx.

And even if some parts use the same IP block, usually the register
interfaces to it are sufficiently different to make common code a
challenge at least (compare MPC5121 and MPC5125).

Yes, some of the later modes share more common IP blocks, but PowerPC
is in no way better than ARM in this respect - the difference is only,
that there are way more different ARM SoCs than there ver have been
PPC ones, so the problems become more visible.

Best regards,

Wolfgang Denk

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