Subject: omap4-panda-es boot issues with v3.15-rc4

From: [email-masked] (Roger Quadros)
Date: Tue, 13 May 2014 11:10:02 +0300

On 05/13/2014 01:07 AM, Tony Lindgren wrote:
> * Santosh Shilimkar <[email-masked]> [140512 14:41]:
>> On Sunday 11 May 2014 11:55 AM, Tony Lindgren wrote:
>>> * Kevin Hilman <[email-masked]> [140509 16:46]:
>>>> Roger Quadros <[email-masked]> writes:
>>>>
>>>>> Kevin,
>>>>>
>>>>> On 05/09/2014 01:15 AM, Kevin Hilman wrote:
>>>>>> Tony Lindgren <[email-masked]> writes:
>>>>>>
>>>>>> [...]
>>>>>>
>>>>>>> ..but I think I found the cause for recent hangs on panda, just a wild
>>>>>>> guess based on looking at the recent cpuidle patches after v3.14.
>>>>>>>
>>>>>>> Looks like reverting 0b89e9aa2856 (cpuidle: delay enabling interrupts
>>>>>>> until all coupled CPUs leave idle) makes booting work reliably again
>>>>>>> on panda.
>>>>>>>
>>>>>>> Can you guys confirm, so far no issues here after few boot tests,
>>>>>>> but it might be too early to tell.
>>>>>>
>>>>>> Reverting that makes things a bit more stable, but it still eventually
>>>>>> fails in the same way.  For me it took 8 boots for it to eventually
>>>>>> fail.
>>>>>>
>>>>>> However, if I build with CONFIG_CPU_IDLE=n, it becomes much more stable
>>>>>> (20+ boots in a row and still going.)
>>>>>>
>>>>>
>>>>> Can you please test with CPU_IDLE enabled but C3 disabled as in below patch?
>>>>> It worked for me 10/10 boots.
>>>>
>>>> Yup, it worked for me too for 10/10 boots in a row.
>>>
>>> But what has caused this regression, does it work reliably with let's
>>> say v3.13 or v3.12?
>>>
>> IIRC things were stable till some CPUIDLE code consolidation happened.
>> I don't recall exactly but some one did discuss about it a while back.
> 
> OK that's good to hear.
>  
>> Can you re-run your test-cases with patch at end of the email. This
>> is just a hunch so don't blame me if I waste your time testing the
>> patch.
> 
> Seems to work after adding "#include <linux/clockchips.h>". I did about 10
> reboots and they all succeeded for me. Without your revert, I'm getting
> a hang (with sysrq not working) about 1/3 of the boots.
> 
> Kevin, Roger, does the revert from Santosh work for you too?
> 

next-20140508 worked for me 10/10 times with Santosh's patch.
The heartbeat LED behaves normally as well. So I like it :).

cheers,
-roger

> BTW, I think the the RCU stall was/is a separate issue. That's different
> where the system actually recovers after about a minute, or after sysrq
> ctrl-a f h or l. Sorry, I no longer know if the RCU stall is only with the
> older kernels around v3.10 time, or if it's still also happening.
> 
> Regards,
> 
> Tony
>  
>> From bdd30d68f8fa659aa0e3ce436f94029a7719036b Mon Sep 17 00:00:00 2001
>> From: Santosh Shilimkar <[email-masked]>
>> Date: Mon, 12 May 2014 17:37:59 -0400
>> Subject: [PATCH] Revert "cpuidle / omap4 : use CPUIDLE_FLAG_TIMER_STOP flag"
>>
>> This reverts commit cb7094e848f7bcaa0a4cda3db4b232f08dbf5b78.
>>
>> Conflicts:
>>
>> 	arch/arm/mach-omap2/cpuidle44xx.c
>> ---
>>  arch/arm/mach-omap2/cpuidle44xx.c |   11 +++++++----
>>  1 file changed, 7 insertions(+), 4 deletions(-)
>>
>> diff --git a/arch/arm/mach-omap2/cpuidle44xx.c b/arch/arm/mach-omap2/cpuidle44xx.c
>> index 01fc710..aae3606 100644
>> --- a/arch/arm/mach-omap2/cpuidle44xx.c
>> +++ b/arch/arm/mach-omap2/cpuidle44xx.c
>> @@ -83,6 +83,7 @@ static int omap_enter_idle_coupled(struct cpuidle_device *dev,
>>  {
>>  	struct idle_statedata *cx = state_ptr + index;
>>  	u32 mpuss_can_lose_context = 0;
>> +	int cpu_id = smp_processor_id();
>>  
>>  	/*
>>  	 * CPU0 has to wait and stay ON until CPU1 is OFF state.
>> @@ -110,6 +111,8 @@ static int omap_enter_idle_coupled(struct cpuidle_device *dev,
>>  	mpuss_can_lose_context = (cx->mpu_state == PWRDM_POWER_RET) &&
>>  				 (cx->mpu_logic_state == PWRDM_POWER_OFF);
>>  
>> +	clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu_id);
>> +
>>  	/*
>>  	 * Call idle CPU PM enter notifier chain so that
>>  	 * VFP and per CPU interrupt context is saved.
>> @@ -165,6 +168,8 @@ static int omap_enter_idle_coupled(struct cpuidle_device *dev,
>>  	if (dev->cpu == 0 && mpuss_can_lose_context)
>>  		cpu_cluster_pm_exit();
>>  
>> +	clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu_id);
>> +
>>  fail:
>>  	cpuidle_coupled_parallel_barrier(dev, &abort_barrier);
>>  	cpu_done[dev->cpu] = false;
>> @@ -189,8 +194,7 @@ static struct cpuidle_driver omap4_idle_driver = {
>>  			/* C2 - CPU0 OFF + CPU1 OFF + MPU CSWR */
>>  			.exit_latency = 328 + 440,
>>  			.target_residency = 960,
>> -			.flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_COUPLED |
>> -			         CPUIDLE_FLAG_TIMER_STOP,
>> +			.flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_COUPLED,
>>  			.enter = omap_enter_idle_coupled,
>>  			.name = "C2",
>>  			.desc = "CPUx OFF, MPUSS CSWR",
>> @@ -199,8 +203,7 @@ static struct cpuidle_driver omap4_idle_driver = {
>>  			/* C3 - CPU0 OFF + CPU1 OFF + MPU OSWR */
>>  			.exit_latency = 460 + 518,
>>  			.target_residency = 1100,
>> -			.flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_COUPLED |
>> -			         CPUIDLE_FLAG_TIMER_STOP,
>> +			.flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_COUPLED,
>>  			.enter = omap_enter_idle_coupled,
>>  			.name = "C3",
>>  			.desc = "CPUx OFF, MPUSS OSWR",
>> -- 
>> 1.7.9.5
>>
>>