[CPUFREQ] Only set sampling_rate_max deprecated, sampling_rate_min is useful

Update the documentation accordingly.
Cleanup and use printk_once.

Signed-off-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Dave Jones <davej@redhat.com>

Documentation/cpu-freq/governors.txt

diff --git a/Documentation/cpu-freq/governors.txt b/Documentation/cpu-freq/governors.txt
index ce73f3eb..aed082f 100644
--- a/Documentation/cpu-freq/governors.txt
+++ b/Documentation/cpu-freq/governors.txt
@@ -119,10 +119,6 @@
 what to do about the frequency.  Typically this is set to values of
 around '10000' or more. It's default value is (cmp. with users-guide.txt):
 transition_latency * 1000
-The lowest value you can set is:
-transition_latency * 100 or it may get restricted to a value where it
-makes not sense for the kernel anymore to poll that often which depends
-on your HZ config variable (HZ=1000: max=20000us, HZ=250: max=5000).
 Be aware that transition latency is in ns and sampling_rate is in us, so you
 get the same sysfs value by default.
 Sampling rate should always get adjusted considering the transition latency
@@ -131,14 +127,20 @@
 echo `$(($(cat cpuinfo_transition_latency) * 750 / 1000)) \
     >ondemand/sampling_rate
 
-show_sampling_rate_(min|max): THIS INTERFACE IS DEPRECATED, DON'T USE IT.
-You can use wider ranges now and the general
-cpuinfo_transition_latency variable (cmp. with user-guide.txt) can be
-used to obtain exactly the same info:
-show_sampling_rate_min = transtition_latency * 500    / 1000
-show_sampling_rate_max = transtition_latency * 500000 / 1000
-(divided by 1000 is to illustrate that sampling rate is in us and
-transition latency is exported ns).
+show_sampling_rate_min:
+The sampling rate is limited by the HW transition latency:
+transition_latency * 100
+Or by kernel restrictions:
+If CONFIG_NO_HZ is set, the limit is 10ms fixed.
+If CONFIG_NO_HZ is not set or no_hz=off boot parameter is used, the
+limits depend on the CONFIG_HZ option:
+HZ=1000: min=20000us  (20ms)
+HZ=250:  min=80000us  (80ms)
+HZ=100:  min=200000us (200ms)
+The highest value of kernel and HW latency restrictions is shown and
+used as the minimum sampling rate.
+
+show_sampling_rate_max: THIS INTERFACE IS DEPRECATED, DON'T USE IT.
 
 up_threshold: defines what the average CPU usage between the samplings
 of 'sampling_rate' needs to be for the kernel to make a decision on

drivers/cpufreq/cpufreq_conservative.c

diff --git a/drivers/cpufreq/cpufreq_conservative.c b/drivers/cpufreq/cpufreq_conservative.c
index 06bfe1c..7fc58af 100644
--- a/drivers/cpufreq/cpufreq_conservative.c
+++ b/drivers/cpufreq/cpufreq_conservative.c
@@ -167,26 +167,13 @@
 /************************** sysfs interface ************************/
 static ssize_t show_sampling_rate_max(struct cpufreq_policy *policy, char *buf)
 {
-	static int print_once;
-
-	if (!print_once) {
-		printk(KERN_INFO "CPUFREQ: conservative sampling_rate_max "
-		       "sysfs file is deprecated - used by: %s\n",
-		       current->comm);
-		print_once = 1;
-	}
+	printk_once(KERN_INFO "CPUFREQ: conservative sampling_rate_max "
+		    "sysfs file is deprecated - used by: %s\n", current->comm);
 	return sprintf(buf, "%u\n", -1U);
 }
 
 static ssize_t show_sampling_rate_min(struct cpufreq_policy *policy, char *buf)
 {
-	static int print_once;
-
-	if (!print_once) {
-		printk(KERN_INFO "CPUFREQ: conservative sampling_rate_max "
-		       "sysfs file is deprecated - used by: %s\n", current->comm);
-		print_once = 1;
-	}
 	return sprintf(buf, "%u\n", min_sampling_rate);
 }
 

drivers/cpufreq/cpufreq_ondemand.c

diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c
index a235114..1911d17 100644
--- a/drivers/cpufreq/cpufreq_ondemand.c
+++ b/drivers/cpufreq/cpufreq_ondemand.c
@@ -205,27 +205,13 @@
 /************************** sysfs interface ************************/
 static ssize_t show_sampling_rate_max(struct cpufreq_policy *policy, char *buf)
 {
-	static int print_once;
-
-	if (!print_once) {
-		printk(KERN_INFO "CPUFREQ: ondemand sampling_rate_max "
-		       "sysfs file is deprecated - used by: %s\n",
-		       current->comm);
-		print_once = 1;
-	}
+	printk_once(KERN_INFO "CPUFREQ: ondemand sampling_rate_max "
+	       "sysfs file is deprecated - used by: %s\n", current->comm);
 	return sprintf(buf, "%u\n", -1U);
 }
 
 static ssize_t show_sampling_rate_min(struct cpufreq_policy *policy, char *buf)
 {
-	static int print_once;
-
-	if (!print_once) {
-		printk(KERN_INFO "CPUFREQ: ondemand sampling_rate_min "
-		       "sysfs file is deprecated - used by: %s\n",
-		       current->comm);
-		print_once = 1;
-	}
 	return sprintf(buf, "%u\n", min_sampling_rate);
 }