|SPI Chip Select behavior:
|With the Blackfin on-chip SPI peripheral, there is some logic tied to the CPHA
|bit whether the Slave Select Line is controlled by hardware (CPHA=0) or
|controlled by software (CPHA=1). However, the Linux SPI bus driver assumes that
|the Slave Select is always under software control and being asserted during
|the entire SPI transfer. - And not just bits_per_word duration.
|In most cases you can utilize SPI MODE_3 instead of MODE_0 to work-around this
|behavior. If your SPI slave device in question requires SPI MODE_0 or MODE_2
|timing, you can utilize the GPIO controlled SPI Slave Select option instead.
|In this case, you should use GPIO based CS for all of your slaves and not just
|the ones using mode 0 or 2 in order to guarantee correct CS toggling behavior.
|You can even use the same pin whose peripheral role is a SSEL,
|but use it as a GPIO instead.