Ira W. Snyder wrote:
On Wed, Jul 08, 2009 at 05:58:50PM -0700, Ira W. Snyder wrote:
On Wed, Jul 08, 2009 at 07:32:26PM -0500, Peter Tyser wrote:
On Thu, 2009-07-09 at 08:24 +0800, Liu Dave-R63238 wrote:
[snip]
Both the DMA and CPU methods are definitely on the same order of magnitude. The time taken by the CFI flash driver is MUCH longer than the SDRAM initialization. I wonder, should the icache be enabled for that as well?
I'll do some more testing when I get back to the office tomorrow.
Ok, I've added back the get_tbms() code, and created a routine to initialize ECC with the CPU. I've inlined my patch below, just for reference.
DMA 945ms CPU 581ms
As an interesting comparison, I also benchmarked the method of using the DDR controller to initialize ECC.
DDRC 129ms
So there you have it. Dave Liu is correct, the CPU method is faster, though definitely on the same order of magnitude with the icache_enable()/icache_disable() patch.
Thanks for the measurements and the update.
I may stick with the DDRC method on my board, the difference is just amazing. The flash init still takes up most of the boot process, however.
Peter, feel free to fold the patch below into your own work. Ira
[snip]
FWIIW, and it doesn't materially change your results, but it would have been better to duplicate the get_tbms() call and put it directly around the *_meminit() calls rather than having the print statements inside the timed part. Since U-Boot printing is a blocking call (generally), you are adding the UART Tx time to your measurement.
#if 0 debug("\nInitializing ECC (using DMA)!\n"); s = get_tbms(); dma_meminit(CONFIG_MEM_INIT_VALUE, dram_size); #else debug("\nInitializing ECC (using CPU)!\n"); s = get_tbms(); cpu_meminit(CONFIG_MEM_INIT_VALUE, dram_size); #endif e = get_tbms();
- s = get_tbms();
+#if 0
- debug("\nInitializing ECC (using DMA)!\n"); dma_meminit(CONFIG_MEM_INIT_VALUE, dram_size);
+#else
- debug("\nInitializing ECC (using CPU)!\n");
- cpu_meminit(CONFIG_MEM_INIT_VALUE, dram_size);
+#endif
e = get_tbms();
debug("\nREADY!\n");
debug("ddr init duration: %ld ms\n", e - s);
/* Clear All ECC Errors */ if ((ddr->err_detect & ECC_ERROR_DETECT_MME) == ECC_ERROR_DETECT_MME)
Thanks, gvb