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@xxxxxxxxxx>
---
Documentation/cpu-freq/cpu-drivers.txt | 6 ++++++
Documentation/cpu-freq/user-guide.txt | 8 ++++----
include/linux/cpufreq.h | 6 ++++--
3 files changed, 14 insertions(+), 6 deletions(-)
diff --git a/Documentation/cpu-freq/cpu-drivers.txt b/Documentation/cpu-freq/cpu-drivers.txt
index c436096..72f70b1 100644
--- 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
--- 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 b60f6ba..04d2e84 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -86,8 +86,10 @@ 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 registered CPU */
--
1.7.12.rc2.18.g61b472e
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