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Message-ID: <BANLkTim4U-CJ_D3VSNzwd23XL3fDXT7onQ@mail.gmail.com>
Date: Thu, 19 May 2011 19:32:22 +0200
From: Linus Walleij <linus.walleij@...aro.org>
To: Colin Cross <ccross@...roid.com>,
Thomas Gleixner <tglx@...utronix.de>
Cc: linux-arm-kernel@...ts-infradead.org,
Russell King <linux@....linux.org.uk>,
linux-kernel@...r.kernel.org,
Santosh Shilimkar <santosh.shilimkar@...com>,
linux-arm-kernel@...ts.infradead.org,
Martin Persson <martin.persson@...ricsson.com>,
Rob Herring <robherring2@...il.com>
Subject: Re: [PATCH] ARM: smp_twd: Reconfigure clockevents after cpufreq change
2011/5/17 Colin Cross <ccross@...roid.com>:
> This patch depends on Thomas Gleixner's patch to add clockevents_reconfigure
> See: https://lkml.org/lkml/2011/5/13/122
Patch set has evolved, see below.
Also note that you more or less reimplement Rob Herrings patch:
http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=6802/1
(no big deal I guess, give him a nod)
To work with Thomas full changeset just create a fresh branch and:
git pull git://git.kernel.org/pub/scm/linux/kernel/git/x86/linux-2.6-tip.git
timers/clockevents
Pls change subject from ARM: to clockevents: and merge through
Thomas tree (IMHO).
> diff --git a/arch/arm/kernel/smp_twd.c b/arch/arm/kernel/smp_twd.c
> index 60636f4..dbf58d4 100644
> --- a/arch/arm/kernel/smp_twd.c
> +++ b/arch/arm/kernel/smp_twd.c
> @@ -10,21 +10,29 @@
> */
> #include <linux/init.h>
> #include <linux/kernel.h>
> +#include <linux/clk.h>
> +#include <linux/cpufreq.h>
> #include <linux/delay.h>
> #include <linux/device.h>
> +#include <linux/err.h>
> #include <linux/smp.h>
> #include <linux/jiffies.h>
> #include <linux/clockchips.h>
> #include <linux/irq.h>
> #include <linux/io.h>
> +#include <linux/percpu.h>
>
> #include <asm/smp_twd.h>
> #include <asm/hardware/gic.h>
>
> +#define TWD_MIN_RANGE 4
> +
Loose this. Let the framework decide using the function below.
> /* set up by the platform code */
> void __iomem *twd_base;
>
> +static struct clk *twd_clk;
> static unsigned long twd_timer_rate;
> +static DEFINE_PER_CPU(struct clock_event_device *, twd_ce);
>
> static void twd_set_mode(enum clock_event_mode mode,
> struct clock_event_device *clk)
> @@ -80,6 +88,49 @@ int twd_timer_ack(void)
> return 0;
> }
>
> +/*
> + * Updates clockevent frequency when the cpu frequency changes.
> + * Called on the cpu that is changing frequency with interrupts disabled.
> + */
> +static void twd_update_frequency(void *data)
> +{
> + twd_timer_rate = clk_get_rate(twd_clk);
> +
> + clockevents_reconfigure(__get_cpu_var(twd_ce), twd_timer_rate,
> + TWD_MIN_RANGE);
Changed name to clockevents_update_freq(), dropped range argument.
> +}
> +
> +static int twd_cpufreq_transition(struct notifier_block *nb,
> + unsigned long state, void *data)
> +{
> + struct cpufreq_freqs *freqs = data;
> +
> + /*
> + * The twd clock events must be reprogrammed to account for the new
> + * frequency. The timer is local to a cpu, so cross-call to the
> + * changing cpu.
> + */
> + if (state == CPUFREQ_POSTCHANGE || state == CPUFREQ_RESUMECHANGE)
> + smp_call_function_single(freqs->cpu, twd_update_frequency,
> + NULL, 1);
> +
> + return NOTIFY_OK;
> +}
> +
> +static struct notifier_block twd_cpufreq_nb = {
> + .notifier_call = twd_cpufreq_transition,
> +};
> +
> +static int twd_cpufreq_init(void)
> +{
> + if (!IS_ERR_OR_NULL(twd_clk))
> + return cpufreq_register_notifier(&twd_cpufreq_nb,
> + CPUFREQ_TRANSITION_NOTIFIER);
> +
> + return 0;
> +}
> +core_initcall(twd_cpufreq_init);
> +
> static void __cpuinit twd_calibrate_rate(void)
> {
> unsigned long count;
> @@ -124,7 +175,16 @@ static void __cpuinit twd_calibrate_rate(void)
> */
> void __cpuinit twd_timer_setup(struct clock_event_device *clk)
> {
> - twd_calibrate_rate();
> + if (twd_clk == NULL) {
> + twd_clk = clk_get_sys("smp_twd", NULL);
> + if (IS_ERR_OR_NULL(twd_clk))
> + pr_warn("%s: no clock found\n", __func__);
> + }
> +
> + if (!IS_ERR_OR_NULL(twd_clk))
> + twd_timer_rate = clk_get_rate(twd_clk);
> + else
> + twd_calibrate_rate();
>
> clk->name = "local_timer";
> clk->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT |
> @@ -132,13 +192,16 @@ void __cpuinit twd_timer_setup(struct clock_event_device *clk)
> clk->rating = 350;
> clk->set_mode = twd_set_mode;
> clk->set_next_event = twd_set_next_event;
> - clk->shift = 20;
> - clk->mult = div_sc(twd_timer_rate, NSEC_PER_SEC, clk->shift);
> +
> + clockevents_calc_mult_shift(clk, twd_timer_rate, TWD_MIN_RANGE);
> +
> clk->max_delta_ns = clockevent_delta2ns(0xffffffff, clk);
> clk->min_delta_ns = clockevent_delta2ns(0xf, clk);
Get rid of everything between clk->shift ... and here and replace it with:
clockevents_config_and_register(clk, twd_timer_rate,
0xf, 0xffffffff);
> /* Make sure our local interrupt controller has this enabled */
> gic_enable_ppi(clk->irq);
>
> + __get_cpu_var(twd_ce) = clk;
> +
> clockevents_register_device(clk);
> }
Or just smack in this patch on top:
>From fd546090b8f0cb5df06103c014466c86cf58b73a Mon Sep 17 00:00:00 2001
From: Linus Walleij <linus.walleij@...ricsson.com>
Date: Thu, 19 May 2011 18:55:22 +0200
Subject: [PATCH] Fix smallish cleanup
---
arch/arm/kernel/smp_twd.c | 13 +++----------
1 files changed, 3 insertions(+), 10 deletions(-)
diff --git a/arch/arm/kernel/smp_twd.c b/arch/arm/kernel/smp_twd.c
index dbf58d4..968f298 100644
--- a/arch/arm/kernel/smp_twd.c
+++ b/arch/arm/kernel/smp_twd.c
@@ -25,8 +25,6 @@
#include <asm/smp_twd.h>
#include <asm/hardware/gic.h>
-#define TWD_MIN_RANGE 4
-
/* set up by the platform code */
void __iomem *twd_base;
@@ -96,8 +94,7 @@ static void twd_update_frequency(void *data)
{
twd_timer_rate = clk_get_rate(twd_clk);
- clockevents_reconfigure(__get_cpu_var(twd_ce), twd_timer_rate,
- TWD_MIN_RANGE);
+ clockevents_update_freq(__get_cpu_var(twd_ce), twd_timer_rate);
}
static int twd_cpufreq_transition(struct notifier_block *nb,
@@ -193,15 +190,11 @@ void __cpuinit twd_timer_setup(struct
clock_event_device *clk)
clk->set_mode = twd_set_mode;
clk->set_next_event = twd_set_next_event;
- clockevents_calc_mult_shift(clk, twd_timer_rate, TWD_MIN_RANGE);
-
- clk->max_delta_ns = clockevent_delta2ns(0xffffffff, clk);
- clk->min_delta_ns = clockevent_delta2ns(0xf, clk);
-
/* Make sure our local interrupt controller has this enabled */
gic_enable_ppi(clk->irq);
__get_cpu_var(twd_ce) = clk;
- clockevents_register_device(clk);
+ clockevents_config_and_register(clk, twd_timer_rate,
+ 0xf, 0xffffffff);
}
--
1.7.3.2
With these changes (provided they work) all should be well, so:
Tested-by: Linus Walleij <linus.walleij@...aro.org>
If all is well on your side as well, ask Thomas to take this into the
timers/clockevents branch where all dependencies are.
Yours,
Linus Walleij
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