linux-kernel - Re: [PATCH] cpufreq: pass policy to ->get() driver callback

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Date:	Thu, 10 Sep 2015 23:36:57 +0200
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	linaro-kernel@...ts.linaro.org, linux-pm@...r.kernel.org,
	Kristen Carlson Accardi <kristen@...ux.intel.com>,
	open list <linux-kernel@...r.kernel.org>,
	Sudeep Holla <sudeep.holla@....com>
Subject: Re: [PATCH] cpufreq: pass policy to ->get() driver callback

On Thursday, September 10, 2015 06:52:22 AM Viresh Kumar wrote:
> On 10-09-15, 03:41, Rafael J. Wysocki wrote:
> > I see one.  That unfortunately is the acpi-cpufreq driver, but it still is one.
> 
> Hmm..
> 
> > Well, cpufreq_generic_get() does _get_raw(), so I suppose acpi-cpufreq may
> > do that too?
> 
> Yeah, it can.

OK, so let's make that change.

BTW, I wonder how much of the stuff in cpufreq.h can be moved to a local header
under drivers/cpufreq/.  It looks like the majority of it is not used by
anybody else.

---
From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Subject: cpufreq: acpi-cpufreq: Use cpufreq_cpu_get_raw() in ->get()

cpufreq_cpu_get() called by get_cur_freq_on_cpu() is overkill,
because the ->get() callback is always invoked in a context in
which all of the conditions checked by cpufreq_cpu_get() are
guaranteed to be satisfied.

Use cpufreq_cpu_get_raw() instead of it and drop the
corresponding cpufreq_cpu_put() from get_cur_freq_on_cpu().

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 drivers/cpufreq/acpi-cpufreq.c |    3 +--
 drivers/cpufreq/cpufreq.c      |    2 +-
 include/linux/cpufreq.h        |    5 +++++
 3 files changed, 7 insertions(+), 3 deletions(-)

Index: linux-pm/drivers/cpufreq/acpi-cpufreq.c
===================================================================
--- linux-pm.orig/drivers/cpufreq/acpi-cpufreq.c
+++ linux-pm/drivers/cpufreq/acpi-cpufreq.c
@@ -375,12 +375,11 @@ static unsigned int get_cur_freq_on_cpu(
 
 	pr_debug("get_cur_freq_on_cpu (%d)\n", cpu);
 
-	policy = cpufreq_cpu_get(cpu);
+	policy = cpufreq_cpu_get_raw(cpu);
 	if (unlikely(!policy))
 		return 0;
 
 	data = policy->driver_data;
-	cpufreq_cpu_put(policy);
 	if (unlikely(!data || !data->freq_table))
 		return 0;
 
Index: linux-pm/drivers/cpufreq/cpufreq.c
===================================================================
--- linux-pm.orig/drivers/cpufreq/cpufreq.c
+++ linux-pm/drivers/cpufreq/cpufreq.c
@@ -238,13 +238,13 @@ int cpufreq_generic_init(struct cpufreq_
 }
 EXPORT_SYMBOL_GPL(cpufreq_generic_init);
 
-/* Only for cpufreq core internal use */
 struct cpufreq_policy *cpufreq_cpu_get_raw(unsigned int cpu)
 {
 	struct cpufreq_policy *policy = per_cpu(cpufreq_cpu_data, cpu);
 
 	return policy && cpumask_test_cpu(cpu, policy->cpus) ? policy : NULL;
 }
+EXPORT_SYMBOL_GPL(cpufreq_cpu_get_raw);
 
 unsigned int cpufreq_generic_get(unsigned int cpu)
 {
Index: linux-pm/include/linux/cpufreq.h
===================================================================
--- linux-pm.orig/include/linux/cpufreq.h
+++ linux-pm/include/linux/cpufreq.h
@@ -129,9 +129,14 @@ struct cpufreq_policy {
 #define CPUFREQ_SHARED_TYPE_ANY	 (3) /* Freq can be set from any dependent CPU*/
 
 #ifdef CONFIG_CPU_FREQ
+struct cpufreq_policy *cpufreq_cpu_get_raw(unsigned int cpu);
 struct cpufreq_policy *cpufreq_cpu_get(unsigned int cpu);
 void cpufreq_cpu_put(struct cpufreq_policy *policy);
 #else
+static inline struct cpufreq_policy *cpufreq_cpu_get_raw(unsigned int cpu)
+{
+	return NULL;
+}
 static inline struct cpufreq_policy *cpufreq_cpu_get(unsigned int cpu)
 {
 	return NULL;

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