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Documentation/blackfin/bfin-spi-notes.txt
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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. |
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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. |
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You can even use the same pin whose peripheral role is a SSEL, but use it as a GPIO instead. |