Re: [PATCH] ACPI, cpuidle: Fix suspend/resume regression caused by cpuidle cleanup.

[Deepthi Dharwar <deepthi@linux.vnet.ibm.com>]

Apologies for the confusion.
Please add the Cc: stable tag for this patch as this regression affects
older kernels too.
  Link to the patch :
  http://permalink.gmane.org/gmane.linux.power-management.general/27614

 Thanks !
 Deepthi

On 06/15/2012 05:46 PM, Deepthi Dharwar wrote:

> Please include this in -stable tree, as this is a regression fix which
> affects older kernels ( 3.1 onwards )


  Sorry for the typo. :(

> Link to the patch : 
> http://permalink.gmane.org/gmane.linux.power-management.general/27614
> 
> Thanks !
> Deepthi
> 
> On 06/14/2012 01:31 AM, Rafael J. Wysocki wrote:
> 
>> On Wednesday, June 13, 2012, Deepthi Dharwar wrote:
>>>
>>> From: Deepthi Dharwar <deepthi@linux.vnet.ibm.com>
>>>
>>> Fix suspend/resume regression caused by cpuidle cleanup.
>>>
>>> Commit e978aa7d7d57d04eb5f88a7507c4fb98577def77 ( cpuidle: Move
>>> dev->last_residency update to driver enter routine; remove dev->last_state)
>>> was  breaking suspend on laptops, as reported in the below link
>>> 	- https://lkml.org/lkml/2011/11/11/164
>>>
>>> This was fixed in commit 3439a8da16bcad6b0982ece938c9f8299bb53584
>>> (ACPI / cpuidle: Remove acpi_idle_suspend (to fix suspend regression)
>>> by removing acpi_idle_suspend flag.
>>> 	- https://lkml.org/lkml/2011/11/14/74
>>>
>>> But this fix did not work on all systems
>>> as Suspend/resume regression was reported on Lenovo S10-3
>>> recently by Dave.
>>> 	- https://lkml.org/lkml/2012/5/27/115
>>> It looked like with commit e978aa7d broke suspend and
>>> with commit 3439a8da resume was not working with acpi_idle driver.
>>>
>>> This patch fixes the regression that caused this issue
>>> in the first place. acpi_idle_suspend flag is essential on
>>> some x86 systems to prevent the cpus from going to deeper C-states
>>> when suspend is triggered ( commit b04e7bdb984 )
>>> So reverting the commit 3439a8da is essential.
>>>
>>> By default, irqs are disabled in cpu_idle arch specific call
>>> and re-enabled in idle state return path . As the acpi_idle_suspend
>>> flag was being set during suspend, which prevented the cpus
>>> going to deeper idle states, it is essential to
>>> enabling the irqs in its return path too.
>>>
>>> To address the suspend issue,
>>> we were not re-enabling the interrupts while returning from
>>> acpi_idle_enter_bm() routine if acpi_idle_suspend flag is set.
>>> and this was causing suspend failure.
>>>
>>> In addition to the above fix, a sanity check has also been added
>>> in x86 arch specific cpu_idle call to ensure that the idle call
>>> always returns with IRQs enabled.
>>>
>>> This patch applies on 3.5-rc2
>>> ---
>>>
>>> Reported-and-Tested-by: Dav Hansen <dave@linux.vnet.ibm.com>
>>> Tested-by: Preeti Murthy <preeti@linux.vnet.ibm.com>
>>> Signed-off-by: Deepthi Dharwar <deepthi@linux.vnet.ibm.com>
>>> Reviewed-by: Srivatsa S Bhat <srivatsa.bhat@linux.vnet.ibm.com>
>>
>> Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
>>
>>> ---
>>>  arch/x86/kernel/process.c     |    6 ++++++
>>>  drivers/acpi/processor_idle.c |   28 ++++++++++++++++++++++++++++
>>>  2 files changed, 34 insertions(+), 0 deletions(-)
>>>
>>> diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
>>> index 735279e..8ab76ad 100644
>>> --- a/arch/x86/kernel/process.c
>>> +++ b/arch/x86/kernel/process.c
>>> @@ -460,6 +460,12 @@ void cpu_idle(void)
>>>  				pm_idle();
>>>
>>>  			rcu_idle_exit();
>>> +
>>> +			/*
>>> +			 * Sanity check to ensure that idle call returns
>>> +			 * with IRQs enabled
>>> +			 */
>>> +			WARN_ON(irqs_disabled());
>>>  			start_critical_timings();
>>>
>>>  			/* In many cases the interrupt that ended idle
>>> diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
>>> index f3decb3..c2ffd84 100644
>>> --- a/drivers/acpi/processor_idle.c
>>> +++ b/drivers/acpi/processor_idle.c
>>> @@ -224,6 +224,7 @@ static void lapic_timer_state_broadcast(struct acpi_processor *pr,
>>>  /*
>>>   * Suspend / resume control
>>>   */
>>> +static int acpi_idle_suspend;
>>>  static u32 saved_bm_rld;
>>>
>>>  static void acpi_idle_bm_rld_save(void)
>>> @@ -242,13 +243,21 @@ static void acpi_idle_bm_rld_restore(void)
>>>
>>>  int acpi_processor_suspend(struct acpi_device * device, pm_message_t state)
>>>  {
>>> +	if (acpi_idle_suspend == 1)
>>> +		return 0;
>>> +
>>>  	acpi_idle_bm_rld_save();
>>> +	acpi_idle_suspend = 1;
>>>  	return 0;
>>>  }
>>>
>>>  int acpi_processor_resume(struct acpi_device * device)
>>>  {
>>> +	if (acpi_idle_suspend == 0)
>>> +		return 0;
>>> +
>>>  	acpi_idle_bm_rld_restore();
>>> +	acpi_idle_suspend = 0;
>>>  	return 0;
>>>  }
>>>
>>> @@ -754,6 +763,12 @@ static int acpi_idle_enter_c1(struct cpuidle_device *dev,
>>>
>>>  	local_irq_disable();
>>>
>>> +	if (acpi_idle_suspend) {
>>> +		local_irq_enable();
>>> +		cpu_relax();
>>> +		return -EINVAL;
>>> +	}
>>> +
>>>  	lapic_timer_state_broadcast(pr, cx, 1);
>>>  	kt1 = ktime_get_real();
>>>  	acpi_idle_do_entry(cx);
>>> @@ -823,6 +838,12 @@ static int acpi_idle_enter_simple(struct cpuidle_device *dev,
>>>
>>>  	local_irq_disable();
>>>
>>> +	if (acpi_idle_suspend) {
>>> +		local_irq_enable();
>>> +		cpu_relax();
>>> +		return -EINVAL;
>>> +	}
>>> +
>>>  	if (cx->entry_method != ACPI_CSTATE_FFH) {
>>>  		current_thread_info()->status &= ~TS_POLLING;
>>>  		/*
>>> @@ -901,6 +922,13 @@ static int acpi_idle_enter_bm(struct cpuidle_device *dev,
>>>  	if (unlikely(!pr))
>>>  		return -EINVAL;
>>>
>>> +	if (acpi_idle_suspend) {
>>> +		if (irqs_disabled())
>>> +			local_irq_enable();
>>> +		cpu_relax();
>>> +		return -EINVAL;
>>> +	}
>>> +
>>>  	if (!cx->bm_sts_skip && acpi_idle_bm_check()) {
>>>  		if (drv->safe_state_index >= 0) {
>>>  			return drv->states[drv->safe_state_index].enter(dev,
>>>
>>> Regards,
>>> Deepthi
>>>
>>>
>>>
>>
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> 
>