tree 6f02bc7b7585c82cb3d4490d1dc7ba77e3bac4f9
parent fa4da365bc7772c2cd6d5405bdf151612455f957
author Thomas Gleixner <tglx@linutronix.de> 1334180956 +0200
committer Thomas Gleixner <tglx@linutronix.de> 1334181905 +0200

Revert "clocksource: Load the ACPI PM clocksource asynchronously"

This reverts commit b519508298e0292e1771eecf14aaf67755adc39d.

The reason for this revert is that making the frequency verification
preemptible and interruptible is not working reliably. Michaels
machine failed to use PM-timer with the message:

  PM-Timer running at invalid rate: 113% of normal - aborting.

That's not a surprise as the frequency verification does rely on
interrupts being disabled. With a async scheduled thread there is no
guarantee to achieve the same result. Also some driver might fiddle
with the CTC channel 2 during the verification period, which makes the
result even more random and unpredictable.

This can be solved by using the same mechanism as we use in the
deferred TSC validation code, but that only will work if we verified a
working HPET _BEFORE_ trying to do the PM-Timer lazy validation.

So for now reverting is the safe option.

Bisected-by: Michael Witten <mfwitten@gmail.com>
Cc: Arjan van de Ven <arjanvandeven@gmail.com>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: John Stultz <johnstul@us.ibm.com>
Cc: Len Brown <lenb@kernel.org>
LKML-Reference: <alpine.LFD.2.02.1204112303270.2542@ionos>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>