[U-Boot] Falcon mode boot support

[Tom Rini <trini@ti.com>]

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.

-- 
Tom
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