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Subject[patch-mm 02/23] ACPI: Move timer broadcast and pmtimer access before C3 arbiter shutdown
From: Udo A. Steinberg <us15@os.inf.tu-dresden.de>

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. It freezes
ICH4 based boxen hard, when HPET is accessed after the arbiter shutdown.

Signed-off-by: Udo A. Steinberg <us15@os.inf.tu-dresden.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Len Brown <lenb@kernel.org>

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

Index: linux-2.6.22-rc4-mm/drivers/acpi/processor_idle.c
===================================================================
--- linux-2.6.22-rc4-mm.orig/drivers/acpi/processor_idle.c 2007-06-10 10:44:37.000000000 +0200
+++ linux-2.6.22-rc4-mm/drivers/acpi/processor_idle.c 2007-06-10 10:44:38.000000000 +0200
@@ -978,6 +978,12 @@ 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);
@@ -997,7 +1003,6 @@ 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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