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SubjectRe: [PATCH] ACPI: Move timer broadcast and pmtimer access before C3 arbiter shutdown
On Wed, 06 Jun 2007 11:37:53 +0200 Thomas Gleixner <tglx@linutronix.de> wrote:

> From: Udo A. Steinberg <us15@os.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@os.inf.tu-dresden.de>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
>
> ---
> drivers/acpi/processor_idle.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> Index: linux-2.6.22-rc4/drivers/acpi/processor_idle.c
> ===================================================================
> --- linux-2.6.22-rc4.orig/drivers/acpi/processor_idle.c 2007-06-06 11:47:21.000000000 +0200
> +++ linux-2.6.22-rc4/drivers/acpi/processor_idle.c 2007-06-06 11:48:21.000000000 +0200
> @@ -488,6 +488,11 @@ static void acpi_processor_idle(void)
>
> case ACPI_STATE_C3:
>
> + /* Get start time (ticks) */
> + t1 = inl(acpi_gbl_FADT.xpm_timer_block.address);
> + /* Handle timer broadcast before bus arbiter shutdown ! */
> + acpi_state_timer_broadcast(pr, cx, 1);
> +
> if (pr->flags.bm_check) {
> if (atomic_inc_return(&c3_cpu_count) ==
> num_online_cpus()) {
> @@ -502,10 +507,7 @@ static void acpi_processor_idle(void)
> ACPI_FLUSH_CPU_CACHE();
> }
>
> - /* Get start time (ticks) */
> - t1 = inl(acpi_gbl_FADT.xpm_timer_block.address);
> /* Invoke C3 */
> - acpi_state_timer_broadcast(pr, cx, 1);
> acpi_cstate_enter(cx);
> /* Get end time (ticks) */
> t2 = inl(acpi_gbl_FADT.xpm_timer_block.address);

hm, this needs a bit of help to get it to work against Len's current tree.

However, if by "non-posted accesses" you're referring to that inl(), how
come the second one which was left in place isn't also a problem?

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