[U-Boot] [PATCH 1/3 v2] 83xx: Default to using DMA to initialize SDRAM

[Peter Tyser]

On Tue, 2009-07-14 at 11:22 +0200, Wolfgang Denk wrote:
> Dear Kim,
> 
> In message <1247098309-29122-2-git-send-email-ptyser at xes-inc.com> Peter Tyse wrote:
> > When SDRAM ECC is enabled and CONFIG_ECC_INIT_VIA_DDRCONTROLLER is not
> > defined use DMA to set SDRAM to a known state.  Previously a sequence of
> > 64-bit stores was used.
> > 
> > Signed-off-by: Peter Tyser <ptyser at xes-inc.com>
> > ---
> >  cpu/mpc83xx/spd_sdram.c  |   57 +++------------------------------------------
> >  drivers/dma/fsl_dma.c    |   16 +++++++++----
> >  include/asm-ppc/config.h |    7 ++---
> >  3 files changed, 18 insertions(+), 62 deletions(-)
> 
> It seems this patch (especially the include/asm-ppc/config.h changes)
> fix build problems for some other (non-FSL) boards, so I would like to
> get this in quickly.
> 
> Do you plan to send a pull request including these patches any time
> soon?
> 
> Alternatively, should I go ahead and apply just this patch (1/3)
> directly?

There was some discussion about whether to use DMA to initialize SDRAM
on the 83xx architecture (which this patch does).  After some
benchmarking by Ira Synder it turns out that using DMA is actually
slower than using the initial method of a series of 64-bit writes.  Thus
I'm assuming Kim would prefer not to use DMA and thus this patch should
be discarded.

Kim, let me know if this is the case and I'll resubmit a patch just to
fix the build error.  Patches 2 and 3 are still applicable even if we
discard patch 1.

Best,
Peter