tree c2b21378f06ea889e7fe51210da730fc7a0b23f4
parent 8559840c4ca3f2fff73a882803bc8916078fac1f
author Thomas Gleixner <tglx@linutronix.de> 1174599978 +0100
committer Linus Torvalds <torvalds@woody.linux-foundation.org> 1174617210 -0700

[PATCH] i386: clockevents fix breakage on Geode/Cyrix PIT implementations

The PIT has no dedicated mode for shut down. The only way to disable PIT
is to put it into one shot mode. AMD implementations of PIT on Geode
(also observed on Cyrix) are confused by an "empty" transition from
CLOCK_EVT_MODE_UNUSED to CLOCK_EVT_MODE_SHUTDOWN, which puts the PIT
into one shot mode momentarily.

I realized after staring helpless at the bug report
http://bugzilla.kernel.org/show_bug.cgi?id=8027 for quite a while, that
the only change, which might influence the bogomips calibration, is the
above transition during the PIT initialization.

Avoiding the unnecessary switch to oneshot and later to periodic mode
fixes the weird bogomips value and also the resulting slowness.

The fix is confirmed on OLPC and another Geode based box.

Note: this is unrelated to the Dual Core problem discussed here:
http://lkml.org/lkml/2007/3/17/48

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>