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| /openbmc/linux/drivers/acpi/ |
| H A D | processor_idle.c | f461ddea Thu Apr 23 17:59:43 CDT 2009 Len Brown <len.brown@intel.com> ACPI/hpet: prevent boot hang when hpet=force used on ICH-4M
Linux tells ICH4 users that they can (manually) invoke
"hpet=force" to enable the undocumented ICH-4M HPET.
The HPET becomes available for both clocksource and clockevents.
But as of ff69f2bba67bd45514923aaedbf40fe351787c59
(acpi: fix of pmtimer overflow that make Cx states time incorrect)
the HPET may be used via clocksource for idle accounting, and
hpet=force on an ICH4 box hangs boot.
It turns out that touching the MMIO HPET withing
the ARB_DIS part of C3 will hang the hardware.
The fix is to simply move the timer access outside
the ARB_DIS region. This is a no-op on modern hardware
because ARB_DIS is no longer used.
http://bugzilla.kernel.org/show_bug.cgi?id=13087
Acked-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
f461ddea Thu Apr 23 17:59:43 CDT 2009 Len Brown <len.brown@intel.com> ACPI/hpet: prevent boot hang when hpet=force used on ICH-4M
Linux tells ICH4 users that they can (manually) invoke
"hpet=force" to enable the undocumented ICH-4M HPET.
The HPET becomes available for both clocksource and clockevents.
But as of ff69f2bba67bd45514923aaedbf40fe351787c59
(acpi: fix of pmtimer overflow that make Cx states time incorrect)
the HPET may be used via clocksource for idle accounting, and
hpet=force on an ICH4 box hangs boot.
It turns out that touching the MMIO HPET withing
the ARB_DIS part of C3 will hang the hardware.
The fix is to simply move the timer access outside
the ARB_DIS region. This is a no-op on modern hardware
because ARB_DIS is no longer used.
http://bugzilla.kernel.org/show_bug.cgi?id=13087
Acked-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
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