linux-kernel - Re: [PATCH] clocksource: sh_tmu: Set cpu_possible

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Date:	Tue, 16 Dec 2014 12:29:12 +0100
From:	Daniel Lezcano <daniel.lezcano@...aro.org>
To:	Laurent Pinchart <laurent.pinchart@...asonboard.com>
CC:	Magnus Damm <magnus.damm@...il.com>, linux-kernel@...r.kernel.org,
	linux-sh@...r.kernel.org, horms@...ge.net.au, geert@...ux-m68k.org,
	tglx@...utronix.de
Subject: Re: [PATCH] clocksource: sh_tmu: Set cpu_possible_mask to fix SMP
 broadcast

On 12/16/2014 12:20 PM, Laurent Pinchart wrote:
> Hi Daniel,
>
> On Tuesday 16 December 2014 12:14:40 Daniel Lezcano wrote:
>> On 12/16/2014 10:48 AM, Magnus Damm wrote:
>>> From: Magnus Damm <damm+renesas@...nsource.se>
>>>
>>> Update the TMU driver to use cpu_possible_mask as cpumask to make
>>> r8a7779 SMP work as expected with or without the ARM TWD timer.
>>>
>>> Signed-off-by: Magnus Damm <damm+renesas@...nsource.se>
>>
>> Applied as a 3.18 fix.
>
> You're a bit too fast, I haven't had time to review the patch yet.

Ah, ok. Hanging on then :)

 >
>> ps: May I suggest to use the CLOCK_EVT_FEAT_DYNIRQ flag for this driver ?
>>
>>> ---
>>>
>>>    drivers/clocksource/sh_tmu.c |    2 +-
>>>    1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> --- 0001/drivers/clocksource/sh_tmu.c
>>> +++ work/drivers/clocksource/sh_tmu.c	2014-12-16 17:49:49.000000000 +0900
>>> @@ -428,7 +428,7 @@ static void sh_tmu_register_clockevent(s
>>>
>>>    	ced->features = CLOCK_EVT_FEAT_PERIODIC;
>>>    	ced->features |= CLOCK_EVT_FEAT_ONESHOT;
>>>    	ced->rating = 200;
>>> -	ced->cpumask = cpumask_of(0);
>>> +	ced->cpumask = cpu_possible_mask;
>
> Magnus, how thoroughly have you tested this ? The TMU is indeed usable by all
> CPUs, so setting the CPU mask to cpu_possible_mask makes sense, but last time
> I've tried that it broke the broadcast timer due to the heuristics used by the
> clock events core code.
>
> Could you please confirm that you've tested both CONFIG_PREEMPT_NONE and
> CONFIG_PREEMPT with and without the ARM TWD times, and that you've booted to
> userspace and tested timer broadcast on all CPUs ?
>
>>>    	ced->set_next_event = sh_tmu_clock_event_next;
>>>    	ced->set_mode = sh_tmu_clock_event_mode;
>>>    	ced->suspend = sh_tmu_clock_event_suspend;
>


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