[U-Boot] at91 spi bus speed

Hi,

I'm experiencing some strange spi behaviour with an at91sam9g20. I changed the spi_xfer code (atmel_spi.c) to make use of the PDC that the at91sam9g20 offers. This works fine, but only up to an spi bus speed of 10 to 12 MHz. After that I see the CS going down sometimes before the transfer is complete. When the frequency is increased the issue starts appearing more often.

I saw that in env_sf.c that the spi bus speed is set at 10 MHz and was wondering if there was a specific reason for that?

10 MHz is acceptible but I would like to understand what is happening, so if anybody experienced and maybe even investigated the problem, please let me know.

Wouter Moors