lkml.org 
[lkml]   [2005]   [Dec]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
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. :)

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]
©2003-2014 Jasper Spaans. Advertise on this site