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Message-ID: <alpine.LRH.2.02.1405141024520.11670@file01.intranet.prod.int.rdu2.redhat.com>
Date: Wed, 14 May 2014 10:25:25 -0400 (EDT)
From: Mikulas Patocka <mpatocka@...hat.com>
To: Viresh Kumar <viresh.kumar@...aro.org>, cpufreq@...r.kernel.org
cc: linux-kernel@...r.kernel.org,
"Rafael J. Wysocki" <rjw@...ysocki.net>, linux-pm@...r.kernel.org
Subject: [PATCH 2/2] speedstep: clean up interrupt disabling
This patch cleans up interrupt disabling in speedstep-smi and
speedstep-lib. It doesn't fix any bug.
speedstep_get_freqs in speedstep-lib may be called from speedstep-smi or
speedstep-ich. When it is called from speedstep-ich, it needs to calculate
transition latency. When it is called from speedstep-smi, transition
latency doesn't have to be calculated.
The function speedstep_set_state in speedstep-smi needs to enable
interrupts. Previously it enabled interrupts even if it was called with
disabled interrupts, but it is dirty.
This patch changes speedstep_get_freqs so that it disables interrupts only
when it is called from speedstep-ich and when it is measuring the
transition latency. This avoids much of the code dirtiness.
Signed-off-by: Mikulas Patocka <mpatocka@...hat.com>
---
drivers/cpufreq/speedstep-lib.c | 13 ++++++-------
drivers/cpufreq/speedstep-smi.c | 11 ++++-------
2 files changed, 10 insertions(+), 14 deletions(-)
Index: linux-3.14-rc1/drivers/cpufreq/speedstep-lib.c
===================================================================
--- linux-3.14-rc1.orig/drivers/cpufreq/speedstep-lib.c 2014-02-03 19:06:21.000000000 +0100
+++ linux-3.14-rc1/drivers/cpufreq/speedstep-lib.c 2014-02-03 19:06:26.000000000 +0100
@@ -400,9 +400,6 @@ unsigned int speedstep_get_freqs(enum sp
pr_debug("previous speed is %u\n", prev_speed);
- preempt_disable();
- local_irq_save(flags);
-
/* switch to low state */
set_state(SPEEDSTEP_LOW);
*low_speed = speedstep_get_frequency(processor);
@@ -414,15 +411,19 @@ unsigned int speedstep_get_freqs(enum sp
pr_debug("low speed is %u\n", *low_speed);
/* start latency measurement */
- if (transition_latency)
+ if (transition_latency) {
+ local_irq_save(flags);
do_gettimeofday(&tv1);
+ }
/* switch to high state */
set_state(SPEEDSTEP_HIGH);
/* end latency measurement */
- if (transition_latency)
+ if (transition_latency) {
do_gettimeofday(&tv2);
+ local_irq_restore(flags);
+ }
*high_speed = speedstep_get_frequency(processor);
if (!*high_speed) {
@@ -464,8 +465,6 @@ unsigned int speedstep_get_freqs(enum sp
}
out:
- local_irq_restore(flags);
- preempt_enable();
return ret;
}
Index: linux-3.14-rc1/drivers/cpufreq/speedstep-smi.c
===================================================================
--- linux-3.14-rc1.orig/drivers/cpufreq/speedstep-smi.c 2014-02-03 19:06:21.000000000 +0100
+++ linux-3.14-rc1/drivers/cpufreq/speedstep-smi.c 2014-02-03 19:06:26.000000000 +0100
@@ -148,16 +148,16 @@ static int speedstep_smi_get_freqs(unsig
static void speedstep_set_state(unsigned int state)
{
unsigned int result = 0, command, new_state, dummy;
- unsigned long flags;
unsigned int function = SET_SPEEDSTEP_STATE;
unsigned int retry = 0;
if (state > 0x1)
return;
- /* Disable IRQs */
+ WARN_ON_ONCE(irqs_disabled());
+
+ /* Disable preemption so that other processes don't run */
preempt_disable();
- local_irq_save(flags);
command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
@@ -177,9 +177,7 @@ static void speedstep_set_state(unsigned
*/
pr_debug("retry %u, previous result %u, waiting...\n",
retry, result);
- local_irq_enable();
mdelay(retry * 50);
- local_irq_disable();
}
retry++;
__asm__ __volatile__(
@@ -194,8 +192,7 @@ static void speedstep_set_state(unsigned
);
} while ((new_state != state) && (retry <= SMI_TRIES));
- /* enable IRQs */
- local_irq_restore(flags);
+ /* enable preemption */
preempt_enable();
if (new_state == state)
--
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