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SubjectRe: [PATCH 2.6-git] SPI: add set_clock() to bitbang
David Brownell wrote:

>>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.
Yeah, but chipselect is called on per-transfer basis what is likely to
be redundant for clock setting.
Per-message clock configuration is enough AFAIS.

>How exactly that's done is system-specific. Many controllers
>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.
Hmm, usually clocks are configured for the bus not device.
So, summarizing, you haven't convinced me yet. :)

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