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

[Peter Tyser]

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...

Thanks,
Peter


diff --git a/drivers/dma/fsl_dma.c b/drivers/dma/fsl_dma.c
index f07b25c..24b31c7 100644
--- a/drivers/dma/fsl_dma.c
+++ b/drivers/dma/fsl_dma.c
@@ -148,6 +148,8 @@ void dma_meminit(uint val, uint size)
        uint *p = 0;
        uint i = 0;
 
+icache_enable()
+printf("%d\n", __LINE__);
        for (*p = 0; p < (uint *)(8 * 1024); p++) {
                if (((uint)p & 0x1f) == 0)
                        ppcDcbz((ulong)p);
@@ -157,6 +159,7 @@ void dma_meminit(uint val, uint size)
                if (((uint)p & 0x1c) == 0x1c)
                        ppcDcbf((ulong)p);
        }
+printf("%d\n", __LINE__);
 
        dmacpy(0x002000, 0, 0x002000); /* 8K */
        dmacpy(0x004000, 0, 0x004000); /* 16K */
@@ -169,7 +172,10 @@ void dma_meminit(uint val, uint size)
        dmacpy(0x200000, 0, 0x200000); /* 2M */
        dmacpy(0x400000, 0, 0x400000); /* 4M */
 
+printf("%d\n", __LINE__);
        for (i = 1; i < size / 0x800000; i++)
                dmacpy((0x800000 * i), 0, 0x800000);
+printf("%d\n", __LINE__);
+icache_disable();
 }
 #endif