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-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.