[PATCH] cpufreq: fix pending powernow timer stuck condition

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AMD recently discovered that on some hardware, there is a race condition
possible when a C-state change request goes onto the bus at the same
time as a P-state change request.

Both requests happen, but the southbridge hardware only acknowledges the
C-state change.  The PowerNow! driver is then stuck in a loop, waiting
for the P-state change acknowledgement.  The driver eventually times
out, but can no longer perform P-state changes.

It turns out the solution is to resend the P-state change, which the
southbridge will acknowledge normally.

Thanks to Johannes Winkelmann for reporting this and testing the fix.

Signed-off-by: Mark Langsdorf <mark.langsdorf@amd.com>
Signed-off-by: Dave Jones <davej@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

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Dave Jones 2005-10-21 17:21:03 -04:00 • committed by Linus Torvalds

parent 3078fcc1d1

commit 0213df7431

1 changed files with 19 additions and 11 deletions

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arch/i386/kernel/cpu/cpufreq/powernow-k8.c

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