linux-kernel - Re: [stable] [PATCH] ACPI: Move timer broadcast and pmtimer access before C3 arbiter shutdown

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Date:	Mon, 11 Jun 2007 18:07:35 -0700
From:	Chris Wright <chrisw@...s-sol.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	LKML <linux-kernel@...r.kernel.org>, Andi Kleen <ak@...e.de>,
	"Udo A. Steinberg" <us15@...inf.tu-dresden.de>,
	Venkatesh Pallipadi <venkatesh.pallipadi@...el.com>,
	Dave Jones <davej@...hat.com>, Ingo Molnar <mingo@...e.hu>,
	Arjan van de Ven <arjan@...radead.org>,
	Stable Team <stable@...nel.org>, Len Brown <lenb@...nel.org>
Subject: Re: [stable] [PATCH] ACPI: Move timer broadcast and pmtimer access
	before C3 arbiter shutdown

* Andrew Morton (akpm@...ux-foundation.org) wrote:
> hm, this needs a bit of help to get it to work against Len's current tree.

Here's some help, compile tested only.  Udo/Thomas, was this found to
be root cause of a real bug?  I didn't want this to get lost if it's
still meant to be relevant for -stable.

thanks,
-chris
--

Subject: ACPI: Move timer broadcast and pmtimer access before C3 arbiter shutdown

From: Udo A. Steinberg <us15@...inf.tu-dresden.de>

The chip set doc for IHC4 says:

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 <us15@...inf.tu-dresden.de>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
[chrisw: rebase against Len's changes in -mm]
Signed-off-by: Chris Wright <chrisw@...s-sol.org>

---

 drivers/acpi/processor_idle.c |    9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 2c6a3cb..15db3e8 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -978,6 +978,11 @@ static int acpi_idle_enter_c3(struct cpuidle_device *dev,
 		return 0;
 	}
 
+	/* 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);
+
 	/* disable bus master */
 	if (pr->flags.bm_check) {
 		spin_lock(&c3_lock);
@@ -995,10 +1000,6 @@ static int acpi_idle_enter_c3(struct cpuidle_device *dev,
 		ACPI_FLUSH_CPU_CACHE();
 	}
 
-	/* 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);
 
 	if (pr->flags.bm_check) {
-
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