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[ts-7000] high resolution timers and real time

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Subject: [ts-7000] high resolution timers and real time
From: Peter Gammie <>
Date: Sat, 16 Jan 2010 23:30:23 +1100
Hello,

I am trying to get a sleep that delays for 1ms (and preferably less) on a 
ts7260. To that end I understand I need the linux kernel's high res timers and 
perhaps the -RT realtime patches.

I managed to apply Matthieu's patch in the file area for 2.6.29.1 to 2.6.29.6, 
and apply the -RT patches to that, but this version does not support the 
high-res timers. The kernel boots but /proc/timers still claims only 10ms 
resolution.

I am trying to port his patch to 2.6.31.6 - the last version for which there is 
an -RT patch - and have managed to get it to compile cleanly. (It seems a few 
of his patches have made it into the mainline now.) Supposedly ARM is amongst 
the supported platforms for high-res timers in this kernel. The ts7260 hangs on 
boot, however.

Is anyone working on this? Does anyone have a known-good approach to getting 
-RT and the high-res timers working on the ts7260? I have trawled the mailing 
list archives but have been thwarted by Yahoo's crappy search. This is most 
promising thread I could find:

http://tech.groups.yahoo.com/group/ts-7000/messages/13979?threaded=1&m=e&var=1&tidx=1

By way of background: I need to control a multiplexed clock with a scanning 
frequency circa 100Hz. I'd like to chew as little CPU as possible, so the ARM 
can go off and do other things. I would like to avoid writing a kernel module 
for something where I really only need a timely timer interrupt.

cheers
peter

-- 
http://peteg.org/



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