cpufreq: Update Documentation for cpus and related_cpus

Documentation related to cpus and related_cpus is confusing and not very clear.
Over that CPUFreq core has seen much changes recently. Lets update documentation
and comments for cpus and related_cpus.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/Documentation/cpu-freq/cpu-drivers.txt b/Documentation/cpu-freq/cpu-drivers.txt
index c436096..72f70b1 100644 (file)
--- a/Documentation/cpu-freq/cpu-drivers.txt
+++ b/Documentation/cpu-freq/cpu-drivers.txt
@@ -111,6 +111,12 @@ policy->governor           must contain the "default policy" for
 For setting some of these values, the frequency table helpers might be
 helpful. See the section 2 for more information on them.
 
+SMP systems normally have same clock source for a group of cpus. For these the
+.init() would be called only once for the first online cpu. Here the .init()
+routine must initialize policy->cpus with mask of all possible cpus (Online +
+Offline) that share the clock. Then the core would copy this mask onto
+policy->related_cpus and will reset policy->cpus to carry only online cpus.
+
 
 1.3 verify
 ------------

diff --git a/Documentation/cpu-freq/user-guide.txt b/Documentation/cpu-freq/user-guide.txt
index 04f6b32..ff2f283 100644 (file)
--- a/Documentation/cpu-freq/user-guide.txt
+++ b/Documentation/cpu-freq/user-guide.txt
@@ -190,11 +190,11 @@ scaling_max_freq          show the current "policy limits" (in
                                first set scaling_max_freq, then
                                scaling_min_freq.
 
-affected_cpus :                        List of CPUs that require software coordination
-                               of frequency.
+affected_cpus :                        List of Online CPUs that require software
+                               coordination of frequency.
 
-related_cpus :                 List of CPUs that need some sort of frequency
-                               coordination, whether software or hardware.
+related_cpus :                 List of Online + Offline CPUs that need software
+                               coordination of frequency.
 
 scaling_driver :               Hardware driver for cpufreq.
 

diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index 5fdc6c6..753b198 100644 (file)
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -89,8 +89,10 @@ struct cpufreq_real_policy {
 };
 
 struct cpufreq_policy {
-       cpumask_var_t           cpus;   /* CPUs requiring sw coordination */
-       cpumask_var_t           related_cpus; /* CPUs with any coordination */
+       /* CPUs sharing clock, require sw coordination */
+       cpumask_var_t           cpus;   /* Online CPUs only */
+       cpumask_var_t           related_cpus; /* Online + Offline CPUs */
+
        unsigned int            shared_type; /* ANY or ALL affected CPUs
                                                should set cpufreq */
        unsigned int            cpu;    /* cpu nr of CPU managing this policy */