From: Udo A. Steinberg <[EMAIL PROTECTED]>

The chipset doc for IHC4 tells us:

1.In general, software should not attempt any non-posted accesses during
arbiter disable except to the ICH4's power management registers.  This implies
that interrupt handlers for any unmasked hardware interrupts and SMI/NMI
should check ARB_DIS status before reading from ICH devices.

So it's not a good idea to access ICH devices after arbiter shut down.

Signed-off-by: Udo A. Steinberg <[EMAIL PROTECTED]>
Signed-off-by: Thomas Gleixner <[EMAIL PROTECTED]>
Cc: Len Brown <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
---

 drivers/acpi/processor_idle.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletion(-)

diff -puN 
drivers/acpi/processor_idle.c~acpi-move-timer-broadcast-and-pmtimer-access-before-c3-arbiter-shutdown
 drivers/acpi/processor_idle.c
--- 
a/drivers/acpi/processor_idle.c~acpi-move-timer-broadcast-and-pmtimer-access-before-c3-arbiter-shutdown
+++ a/drivers/acpi/processor_idle.c
@@ -1009,6 +1009,12 @@ static int acpi_idle_enter_c3(struct cpu
                return 0;
        }
 
+       /*
+        * Must be done before busmaster disable as we might need to
+        * access HPET!
+        */
+       acpi_state_timer_broadcast(pr, cx, 1);
+
        /* disable bus master */
        if (pr->flags.bm_check) {
                spin_lock(&c3_lock);
@@ -1028,7 +1034,6 @@ static int acpi_idle_enter_c3(struct cpu
 
        /* Get start time (ticks) */
        t1 = inl(acpi_gbl_FADT.xpm_timer_block.address);
-       acpi_state_timer_broadcast(pr, cx, 1);
        acpi_idle_do_entry(cx);
        t2 = inl(acpi_gbl_FADT.xpm_timer_block.address);
 
_
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