Yeah, but chipselect is called on per-transfer basis what is likely to be redundant for clock setting.No, suppose there're two devices behind the same SPI bus that have different clock constraints. As active SPI device change may well happen when each new message is processed, we'll need to set up clocks again for each message. Right?
Clock is coupled to chipselect/device. When the bus controller
switches to the other device, it updates the clock accordingly.
How exactly that's done is system-specific. Many controllersHmm, usually clocks are configured for the bus not device.
just have a register per chipselect, listing stuff like SPI mode,
clock divisor, and word size. So switching to that chipselect
kicks those in automatically ... devices ignore the clock unless
they've been selected.