cpuidle/powerpc: Fix smt_snooze_delay functionality.
authorDeepthi Dharwar <deepthi@linux.vnet.ibm.com>
Wed, 3 Oct 2012 18:42:18 +0000 (18:42 +0000)
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>
Wed, 17 Oct 2012 23:57:24 +0000 (10:57 +1100)
commit8ea959a17fe6e27f7954dddad5b17b0e33f0d7ee
treee16bf4c3b7a9bbcb2822c862fccf7b1b8ab336b0
parent817deb05df45577d4037230f2facee486c11d9df
cpuidle/powerpc: Fix smt_snooze_delay functionality.

smt_snooze_delay was designed to  delay idle loop's nap entry
in the native idle code before it got  ported over to use as part of
the cpuidle framework.

A -ve value  assigned to smt_snooze_delay should result in
busy looping, in other words disabling the entry to nap state.

- https://lists.ozlabs.org/pipermail/linuxppc-dev/2010-May/082450.html

This particular functionality can be achieved currently by
echo 1 > /sys/devices/system/cpu/cpu*/state1/disable
but it is broken when one assigns -ve value to  the smt_snooze_delay
variable either via sysfs entry or ppc64_cpu util.

This patch aims to fix this, by disabling nap state when smt_snooze_delay
variable is set to -ve value.

Signed-off-by: Deepthi Dharwar <deepthi@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
arch/powerpc/include/asm/processor.h
arch/powerpc/kernel/sysfs.c
arch/powerpc/platforms/pseries/processor_idle.c