Messages in this thread |  | | | Date | Fri, 23 Dec 2005 10:08:44 +0300 | | From | Vitaly Wool <> | | Subject | Re: [PATCH 2.6-git] SPI: add set_clock() to bitbang |
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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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