On Wed, Dec 17, 2014 at 04:27:37PM -0000, Andy Pont wrote:

Hi Tom,

Following the experiment that yielded the following results:

...

U-Boot> time sf read ${loadaddr} 0x200000 ${loadsize}

I get the following back:

SF: 2541352 bytes @ 0x200000 Read: OK time: 2.447 seconds

I have done some reading and poking around and have added the OMAP3_MCSPI_CHCONF_TURBO flag to the SPI channel enablement in the omap3_spi_read() function within omap3_spi.c and now the same command takes 1.279 seconds to execute.

I have also added a couple of printf() statements around the call to read the flash device that loads the kernel image in spi_load_image_os() and the timestamps on the output to the serial console consistently show that it is taking around 3.5 seconds to load the same kernel image.

I haven't fully looked into what is going on as I haven't yet found the full call path from spi_flash_read() in spi_flash.h to when it eventually results in the call to omap3_spi_read() and so it may be doing more and I'm not actually comparing apples with apples.

Could you (or maybe Jagannadha as SPI custodian) point me in the right direction?

I suspect that this might be related to the general problem on these part families where SPL isn't as fast as we expect it to be, perhaps cache related.