* Update frequency of Time Base reg?
@ 2004-10-08 21:42 Arrigo Benedetti
2004-10-08 22:02 ` Chris Friesen
2004-10-11 9:52 ` Segher Boessenkool
0 siblings, 2 replies; 7+ messages in thread
From: Arrigo Benedetti @ 2004-10-08 21:42 UTC (permalink / raw)
To: linuxppc-dev
Dear all,
I'm looking for information about the update frequency of the Time Base
register
for the latest dual G5 Powermac and Xserve models.
By the way, what is the best way to find this kind of information?
Thanks,
-Arrigo
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Update frequency of Time Base reg?
2004-10-08 21:42 Update frequency of Time Base reg? Arrigo Benedetti
@ 2004-10-08 22:02 ` Chris Friesen
2004-10-11 9:52 ` Segher Boessenkool
1 sibling, 0 replies; 7+ messages in thread
From: Chris Friesen @ 2004-10-08 22:02 UTC (permalink / raw)
To: Arrigo Benedetti; +Cc: linuxppc-dev
Arrigo Benedetti wrote:
> Dear all,
>
> I'm looking for information about the update frequency of the Time Base
> register
> for the latest dual G5 Powermac and Xserve models.
> By the way, what is the best way to find this kind of information?
33.3 MHz, I think.
The most portable way to find it is to calibrate it against gettimeofday(). For
our product kernels, I've exported it via /proc.
Chris
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Update frequency of Time Base reg?
2004-10-08 21:42 Update frequency of Time Base reg? Arrigo Benedetti
2004-10-08 22:02 ` Chris Friesen
@ 2004-10-11 9:52 ` Segher Boessenkool
2004-10-12 5:13 ` Chris Friesen
1 sibling, 1 reply; 7+ messages in thread
From: Segher Boessenkool @ 2004-10-11 9:52 UTC (permalink / raw)
To: Arrigo Benedetti; +Cc: linuxppc-dev
> I'm looking for information about the update frequency of the Time
> Base register
> for the latest dual G5 Powermac and Xserve models.
> By the way, what is the best way to find this kind of information?
Look in the device-tree.
Segher
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Update frequency of Time Base reg?
2004-10-11 9:52 ` Segher Boessenkool
@ 2004-10-12 5:13 ` Chris Friesen
2004-10-12 9:04 ` Segher Boessenkool
0 siblings, 1 reply; 7+ messages in thread
From: Chris Friesen @ 2004-10-12 5:13 UTC (permalink / raw)
To: Segher Boessenkool; +Cc: Arrigo Benedetti, linuxppc-dev
Segher Boessenkool wrote:
>> I'm looking for information about the update frequency of the Time
>> Base register
>> for the latest dual G5 Powermac and Xserve models.
>> By the way, what is the best way to find this kind of information?
>
>
> Look in the device-tree.
Look where in which device tree?
dmesg shows it, but I wasn't aware of any reliable way to get it from userspace
on all ppc boxes.
Chris
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Update frequency of Time Base reg?
2004-10-12 5:13 ` Chris Friesen
@ 2004-10-12 9:04 ` Segher Boessenkool
2004-10-12 14:33 ` Jon Masters
0 siblings, 1 reply; 7+ messages in thread
From: Segher Boessenkool @ 2004-10-12 9:04 UTC (permalink / raw)
To: Chris Friesen; +Cc: linuxppc-dev, Arrigo Benedetti
> Look where in which device tree?
In the "timebase-frequency" property under any CPU node.
Segher
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Update frequency of Time Base reg?
2004-10-12 9:04 ` Segher Boessenkool
@ 2004-10-12 14:33 ` Jon Masters
2004-10-12 15:51 ` Chris Friesen
0 siblings, 1 reply; 7+ messages in thread
From: Jon Masters @ 2004-10-12 14:33 UTC (permalink / raw)
To: Segher Boessenkool; +Cc: linuxppc-dev, Arrigo Benedetti
On Tue, 12 Oct 2004 11:04:06 +0200, Segher Boessenkool
<segher@kernel.crashing.org> wrote:
> > Look where in which device tree?
>
> In the "timebase-frequency" property under any CPU node.
so e.g. in /proc/device-tree/cpus/PowerPC,G4/timebase-frequency.
Jon.
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Update frequency of Time Base reg?
2004-10-12 14:33 ` Jon Masters
@ 2004-10-12 15:51 ` Chris Friesen
0 siblings, 0 replies; 7+ messages in thread
From: Chris Friesen @ 2004-10-12 15:51 UTC (permalink / raw)
To: jonathan; +Cc: linuxppc-dev, Arrigo Benedetti
Jon Masters wrote:
> so e.g. in /proc/device-tree/cpus/PowerPC,G4/timebase-frequency.
Interesting. Learn something new....
Just took a look at the code, and there are apparently some machines on which
this is flaky. To use this in userspace you'd want to account for that, and
probably you'd want a backup calibration as well.
Chris
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2004-10-12 15:51 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz follow: Atom feed
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2004-10-08 21:42 Update frequency of Time Base reg? Arrigo Benedetti
2004-10-08 22:02 ` Chris Friesen
2004-10-11 9:52 ` Segher Boessenkool
2004-10-12 5:13 ` Chris Friesen
2004-10-12 9:04 ` Segher Boessenkool
2004-10-12 14:33 ` Jon Masters
2004-10-12 15:51 ` Chris Friesen
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