[PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver
Matt Sealey
matt at genesi-usa.com
Fri May 18 22:39:26 EST 2007
Sergei Shtylyov wrote:
> Hello.
>
> Kumar Gala wrote:
>
>>> Kumar Gala wrote:
>
>>>> I haven't looked at all the new clock/timer code, is there any
>>>> utility in having support for more than one clock source?
>
>>> Of course, you may register as many as you like.
>
>> Sure, but is there any utility in registering more than the decrementer
>> on PPC?
>
> Not yet. I'm not sure I know any other PPC CPU facility fitting for
> clockevents. In theory, FIT could be used -- but its period is measured in
> powers of 2, IIRC.
Wouldn't it be possible to use SoC timer functionality, too, and not limit
this to what is only present on the CPU die?
I guess the real question is, how high resolution does a high resolution
timer need to be, and how often do you want to be handling interrupts?
The 52XX has 8 general purpose timers and 2 slice timers. Both will
generate an interrupt once the clock hits a preset value, the timing
of which is determined by prescalers and the IPB clock..
--
Matt Sealey <matt at genesi-usa.com>
Genesi, Manager, Developer Relations
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