Hi,
I have u-boot data saved in spi flash. during system boot up SPI flash controller in the SoC reads the u-boot data into DDR. Can any one explain what exactly is PIO mode in SPI. How is it different from SPI modes 0 & 3.
That's nothing SPI specific. PIO mode is used in memory interface specifications in contrast to DMA mode, it's originated from PATA hard disk interface.
The SPI bus is by packaging one or the omap2_mcspi controller transfers less then 8 bytes use PIO mode . I've dropped the two patches that are already applied in Mark's SPI tree .