Commit | Line | Data |
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3322c7bb MH |
1 | SPI Chip Select behavior: |
2 | ||
3 | With the Blackfin on-chip SPI peripheral, there is some logic tied to the CPHA | |
4 | bit whether the Slave Select Line is controlled by hardware (CPHA=0) or | |
5 | controlled by software (CPHA=1). However, the Linux SPI bus driver assumes that | |
6 | the Slave Select is always under software control and being asserted during | |
7 | the entire SPI transfer. - And not just bits_per_word duration. | |
8 | ||
9 | In most cases you can utilize SPI MODE_3 instead of MODE_0 to work-around this | |
10 | behavior. If your SPI slave device in question requires SPI MODE_0 or MODE_2 | |
11 | timing, you can utilize the GPIO controlled SPI Slave Select option instead. | |
10617340 MF |
12 | In this case, you should use GPIO based CS for all of your slaves and not just |
13 | the ones using mode 0 or 2 in order to guarantee correct CS toggling behavior. | |
3322c7bb MH |
14 | |
15 | You can even use the same pin whose peripheral role is a SSEL, | |
16 | but use it as a GPIO instead. |