UCLK
Andy Green
andy at openmoko.com
Wed Aug 27 17:17:47 CEST 2008
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Somebody in the thread at some point said:
| In a message from Ben Dooks on linux-arm-kernel about cpufreq, he said:
|
| > > - My patches have code to use hardware flow control to "pause" the
| > > serial ports during frequency transitions, so as to not confuse the
| > > GTA01 GSM modem (or Openmoko's gsmd).
| >
| > That is useful for designs that forgot to provide a stable UCLK to
| > provide UART baud clocks... all of the ones that I've had a direct
| > hand in working on feed back or feed in an external known (and stable)
| > clock.
|
| It might be worth considering this on future designs (looking at the
| schematics, GTA01 uses the pin for something else, while GTA02 doesn't
| connect the pin at all).
It's a good point, it would help the UART continuity during clock
change. But it means adding an oscillator somewhere? There's a PLL
from the Wolfson we could maybe use.
- -Andy
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