linux-kernel - Re: [PATCH 8/8] ARM: smp: Remove local timer API

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Date:	Mon, 04 Mar 2013 15:50:22 -0800
From:	Stephen Boyd <sboyd@...eaurora.org>
To:	Mark Rutland <mark.rutland@....com>
CC:	Paul Mundt <lethal@...ux-sh.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-arm-msm@...r.kernel.org" <linux-arm-msm@...r.kernel.org>,
	Russell King <linux@....linux.org.uk>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 8/8] ARM: smp: Remove local timer API

On 02/25/13 05:40, Mark Rutland wrote:
> I've had a quick go at writing a generic timer driver. I've not had a chance to
> test it, and there are a couple of things that are up for discussion (e.g. what
> should the rating be) but I think we want something very close to this.
>

This looks good to me. I only have some minor comments. What's the plan
for merging? Get tglx to take this and provide a stable branch and then
base my patches off that and get these patches taken through arm-soc?

> diff --git a/drivers/clocksource/dummy_timer.c b/drivers/clocksource/dummy_timer.c
> new file mode 100644
> index 0000000..bdaba34
> --- /dev/null
> +++ b/drivers/clocksource/dummy_timer.c
> @@ -0,0 +1,67 @@
> +/*
> + *  linux/drivers/clocksource/dummy_timer.c
> + *
> + *  Copyright (C) 2013 ARM Ltd.
> + *  All Rights Reserved
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +#include <linux/clockchips.h>
> +#include <linux/cpu.h>
> +#include <linux/init.h>
> +#include <linux/percpu.h>
> +
> +DEFINE_PER_CPU(struct clock_event_device, dummy_evt);

static?

> +
> +static void dummy_set_mode(enum clock_event_mode mode,
> +			   struct clock_event_device *evt)
> +{
> +	/*
> +	 * Core clockevents code will call this when exchanging timer devices.
> +	 * We don't need to do anything here.
> +	 */
> +}
> +
> +static void __cpuinit dummy_setup(void)
> +{
> +	int cpu = smp_processor_id();
> +	struct clock_event_device *evt = &per_cpu(dummy_evt, cpu);

Can we use __this_cpu_ptr()? I wonder if that makes the code generation
better or worse. I didn't do it in my 8/8 patch because I wanted the
code to be the same before and after to show code movement.

> +
> +	evt->name	= "dummy timer";
> +	evt->features	= CLOCK_EVT_FEAT_PERIODIC |
> +			  CLOCK_EVT_FEAT_ONESHOT |
> +			  CLOCK_EVT_FEAT_DUMMY;
> +	evt->rating	= 100;
> +	evt->set_mode	= dummy_set_mode;
> +	evt->cpumask	= cpumask_of(cpu);
> +
> +	clockevents_register_device(evt);
> +}
> +
> +static int __cpuinit dummy_cpu_notify(struct notifier_block *self,
> +				      unsigned long action, void *hcpu)
> +{
> +	if ((action & ~CPU_TASKS_FROZEN) == CPU_STARTING)
> +		dummy_setup();

There are already two dummy_setup() functions. Perhaps we can
s/dummy/dummy_broadcast/ throughout this file?

-- 
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