[patch-mm 02/23] ACPI: Move timer broadcast and pmtimer access beforeC3 arbiter shutdown

[Thomas Gleixner]

From: Udo A. Steinberg <us15@xxxxxxxxxxxxxxxxxxxx>

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@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Len Brown <lenb@xxxxxxxxxx>

---
 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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