linux-kernel - Re: [PATCH] ARM: hw_breakpoint: Enable debug powerdown only if system supports 'has

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Date:	Wed, 13 Mar 2013 17:59:20 +0530
From:	Lokesh Vutla <lokeshvutla@...com>
To:	Dietmar Eggemann <dietmar.eggemann@....com>
CC:	Will Deacon <Will.Deacon@....com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>,
	"santosh.shilimkar@...com" <santosh.shilimkar@...com>
Subject: Re: [PATCH] ARM: hw_breakpoint: Enable debug powerdown only if system
 supports 'has_ossr'

Hi Dietmar,
On Wednesday 13 March 2013 05:35 PM, Dietmar Eggemann wrote:
> On 13/03/13 06:52, Lokesh Vutla wrote:
>> Commit {9a6eb31 ARM: hw_breakpoint: Debug powerdown support for
>> self-hosted
>> debug} introduces debug powerdown support for self-hosted debug.
>> While merging the patch 'has_ossr' check was removed which
>> was needed for hardwares which doesn't support self-hosted debug.
>> Pandaboard (A9) is one such hardware and Dietmar's orginial
>> patch did mention this issue.
>> Without that check on Panda with CPUIDLE enabled, a flood of
>> below messages thrown.
>>
>> [ 3.597930] hw-breakpoint: CPU 0 failed to disable vector catch
>> [ 3.597991] hw-breakpoint: CPU 1 failed to disable vector catch
>>
>
> Hi Lokesh,
>
> I confirm that this has_ossr condition has to go back into the
> pm_init(void) call. I just verified it again on my Panda board and I get
> the same issue like you without it.
>
> I guess what was happening is that Will asked me if this check is really
> necessary and I said No without re-testing on my Panda board as an V7
> debug architecture example where OSSR is not implemented. Since then I
> only tested in on V7.1 debug architectures where OSSR is mandatory.
> Sorry about this and thanks for catching this.
Thanks for confirming..:)

Regards,
Lokesh

>
> You can add my Acked-by: if you wish.
>
> -- Dietmar
>
>> So restore that check back to avoid the mentioned issue.
>>
>> Cc: Dietmar Eggemann <dietmar.eggemann@....com>
>> Cc: Will Deacon <will.deacon@....com>
>> Reported-by: Santosh Shilimkar <santosh.shilimkar@...com>
>> Acked-by: Santosh Shilimkar <santosh.shilimkar@...com>
>> Signed-off-by: Lokesh Vutla <lokeshvutla@...com>
>> ---
>>   arch/arm/kernel/hw_breakpoint.c |    3 ++-
>>   1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/arm/kernel/hw_breakpoint.c
>> b/arch/arm/kernel/hw_breakpoint.c
>> index 96093b7..0ba062d 100644
>> --- a/arch/arm/kernel/hw_breakpoint.c
>> +++ b/arch/arm/kernel/hw_breakpoint.c
>> @@ -1049,7 +1049,8 @@ static struct notifier_block __cpuinitdata
>> dbg_cpu_pm_nb = {
>>
>>   static void __init pm_init(void)
>>   {
>> -     cpu_pm_register_notifier(&dbg_cpu_pm_nb);
>> +     if (has_ossr)
>> +             cpu_pm_register_notifier(&dbg_cpu_pm_nb);
>>   }
>>   #else
>>   static inline void pm_init(void)
>>
>
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