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

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Date:	Wed, 13 Mar 2013 12:05:59 +0000
From:	Dietmar Eggemann <dietmar.eggemann@....com>
To:	Lokesh Vutla <lokeshvutla@...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'

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.

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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