[U-Boot] [PATCH 0/3] DMA ECC update

[Peter Tyser]

On Wed, 2009-07-08 at 16:13 -0700, Ira W. Snyder wrote:
> On Wed, Jul 08, 2009 at 05:59:33PM -0500, Peter Tyser wrote:
> > On Wed, 2009-07-08 at 15:31 -0700, Ira W. Snyder wrote:
> > > On Wed, Jul 08, 2009 at 02:28:39PM -0500, Peter Tyser wrote:
> > > > These changes bring the 83xx SDRAM ECC initialization in line
> > > > with the 85xx/86xx boards and also fixes a minor bug in fsl_dma.c.
> > > > 
> > > > I don't have any 83xx boards to test on, so it would be appreciated
> > > > if someone with 83xx hardware that uses ECC could give the patches
> > > > a shot.
> > > > 
> > > > It'd be nice if SDRAM could be initialized via the DDR controller
> > > > with CONFIG_ECC_INIT_VIA_DDRCONTROLLER on the 83xx platform too,
> > > > but I'm not going to tackle it:)
> > > > 
> > > > The patches also resolve the compile error Stefan brought up with
> > > > non-freescale boards with CONFIG_ECC.
> > > > 
> > > > Peter Tyser (3):
> > > >   83xx: Default to using DMA to initialize SDRAM
> > > >   83xx: Added CONFIG_MEM_INIT_VALUE for boards with ECC
> > > >   fsl_dma: Fix SDRAM initial value
> > > > 
> > > 
> > > Something in this patch makes the ECC DDR initialization VERY slow. It
> > > used to take <5 seconds, now it takes ~20 seconds for the memory to
> > > initialize.
> > > 
> > > I wonder why the CPU method would be so much faster?
> > > 
> > > Other than the speed, I can confirm that it works as expected on my
> > > 8349emds-based board. I see no reason why there would be a problem on
> > > the mpc8349emds, though I cannot test on the eval board itself. I do not
> > > have an ECC SDRAM module.
> > 
> > Thanks for testing Ira.  The original code had the instruction cache
> > enabled during SDRAM init, but it'd be pretty amazing if it gave that
> > much performance boost.  I would have guessed that the DMA init would
> > have been faster even without the icache enabled.
> > 
> > If you have a second, could you try adding this patch on top of the
> > previous ones?  It'd be interesting to see where the bottleneck is with
> > and without the icache...
> > 
> 
> It didn't apply cleanly (I'm not sure why), but I applied it (fixed the
> missing semicolon).
> 
> It makes the DMA initialization normal speed again. The DMA in the for
> loop takes the longest (as expected).
> 
> So yes, strangely it makes a HUGE difference. The total time is <3
> seconds now. It is now faster than the previous CPU method.

Thanks a lot Ira, I'll resubmit with the cache enable/disable for 83xx.

Peter