Hi Peter -
--- In Peter Gammie <> wrote:
>
> 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.
The HRT, clockevents & dyntick support for ep93xx were in the -rt patchset at
one time, but seem to have been dropped some time ago. I don't recall the
exact versions, but there was a lull in -rt development and the ep93xx support
didn't make the forward port to the next -rt patch. Probably just an oversight.
>
> 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.
If you just need HRT support, check the thread here:
http://marc.info/?l=linux-arm-kernel&m=124825390601431&w=4
You may not need the full -rt patch if you can use HRT and pre-empt.
Probably should ask on linux-arm-kernel ML, or linux-rt-user list. I'm sure if
you could pin-point the regression in the -rt patch, they'd fix it up.
regards, ............ Charlie
>
> cheers
> peter
>
> --
> http://peteg.org/
>
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