linux-kernel - Re: [PATCH 1/2] clocksource: arm_arch_timer: unify sched

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Message-ID: <51708918.1070501@codeaurora.org>
Date:	Thu, 18 Apr 2013 17:00:24 -0700
From:	Stephen Boyd <sboyd@...eaurora.org>
To:	Rob Herring <robherring2@...il.com>
CC:	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	arm@...nel.org, Rob Herring <rob.herring@...xeda.com>,
	Russell King <linux@....linux.org.uk>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>,
	John Stultz <john.stultz@...aro.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 1/2] clocksource: arm_arch_timer: unify sched_clock init

On 04/18/13 12:30, Rob Herring wrote:
> diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
> index 122ff05..17ed8e4 100644
> --- a/drivers/clocksource/arm_arch_timer.c
> +++ b/drivers/clocksource/arm_arch_timer.c
> @@ -266,6 +266,15 @@ static struct notifier_block arch_timer_cpu_nb __cpuinitdata = {
>  	.notifier_call = arch_timer_cpu_notify,
>  };
>  
> +static u64 sched_clock_mult __read_mostly;
> +
> +unsigned long long notrace arch_timer_sched_clock(void)
> +{
> +	return arch_timer_read_counter() * sched_clock_mult;
> +}
> +unsigned long long sched_clock(void) \
> +	__attribute__((weak, alias("arch_timer_sched_clock")));

I'm still lost, how does this prevent the timer in ARM's 32 bit
sched_clock code from getting setup in sched_clock_postinit()? That
print is still there right? Who owns sched_clock() in multi-target builds?

Why can't we play along with the sched_clock code that lives in arm?
Maybe we should resurrect those clocksource sched_clock patches again.
Or maybe we should add support for setup_sched_clock_64() in arm's sched
clock code.

-- 
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