[U-Boot] da850/L138 SPI flash transfer speed

[Wolfgang Denk]

Dear Delio Brignoli,

please mind the NetiQuette and restrict your line length to some 70
charatcers or so.  Thanks.

In message <4D573595-069A-4490-AF2D-38ED3AAD70EB at audioscience.com> you wrote:
> 
> I am working on reducing boot time on an L138 EVM and SPI flash transfer speed is currently the worst offender. U-Boot transfers from the SPI flash at 0.6Mbytes/s, this a lot slower than I would expect for a 50MHz SPI clock. Using a scope we found that 
> the chip select is active throughout the transfer (as expected), we see ~160ns bursts of activity on the clock line for each byte transferred (8 bits @ 50MHz) with 1us idle periods in between. Where does the 1us delay between byte transfers come from? I
> s reading data bytes from the SPI registers very slow or is writing to RAM one byte at a time slowing the transfer?

Everything is slow as caches are not enabled.


Best regards,

Wolfgang Denk

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