![]() | |||||||||||||
Messages in this thread |
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. :) Vitaly - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||||
| Last update: 2005-12-23 08:14 [from the cache] ©2003-2008 | |||||||||||||