On Thu, 2009-07-09 at 08:24 +0800, Liu Dave-R63238 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.
IIRC, the DMA init SDRAM is slower than the 64bit stores. It is why I added these code here.
I suggest to keep the way.
According to Ira, the DMA method was faster than the cpu method: "It makes the DMA initialization normal speed again. The DMA in the for loop takes the longest (as expected).
So yes, strangely it (enabling the icache) makes a HUGE difference. The total time is <3 seconds now. It is now faster than the previous CPU method."
Logically the DMA method should be faster, and Ira's results seem to reinforce this. I don't have an 83xx board to test on, so let me know if others have different results than Ira.
Best, Peter