>-----Original Message-----
>From: Andrew Morton [mailto:[email protected]]
>Sent: Wednesday, June 06, 2007 6:39 PM
>To: Thomas Gleixner
>Cc: Pallipadi, Venkatesh; Stable Team; LKML; Len Brown; Ingo
>Molnar; Arjan van de Ven; Andi Kleen; Udo A. Steinberg; Dave Jones
>Subject: Re: [PATCH] ACPI: Move timer broadcast and pmtimer
>access before C3 arbiter shutdown
>
>On Wed, 06 Jun 2007 11:37:53 +0200 Thomas Gleixner
><[email protected]> wrote:
>
>> From: Udo A. Steinberg <[email protected]>
>>
>> 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 <[email protected]>
>> Signed-off-by: Thomas Gleixner <[email protected]>
>>
>> ---
>> 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?
>
The doc says "except to the ICH4's power management registers".
It seems acpi_gbl_FADT.xpm_timer_block.address is actually OK in this
case
as it is ACPI PM timer register.
The problem we had is the access to HPET registers
inside acpi_state_timer_broadcast() and that is the one that has to be
done
before ARB_DIS.
Thanks,
Venki
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