ACPI: restore comment justifying 'extra' P_LVLx access

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While trying to look for superfluous I/O accesses that can be optimized
away, I stumbled upon this ACPI sleep I/O access and couldn't figure out
why the hell this dummy op was necessary.
After more than one hour of internet research, I had collected a sufficient
number of documents (among those very old kernel versions) that finally
told me what this dummy read was about: STPCLK# doesn't get asserted in time
on (some) chipsets, which is why we need to have a dummy I/O read to delay
further instruction processing until the CPU is fully stopped.

Signed-off-by: Andreas Mohr <andi@lisas.de>
Signed-off-by: Len Brown <len.brown@intel.com>

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Andreas Mohr 2006-06-26 15:58:00 -04:00 • committed by Len Brown

parent 95b38b3f45

commit b488f02156

1 changed files with 4 additions and 2 deletions

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6

drivers/acpi/processor_idle.c

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