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-rw-r--r--Documentation/cpu-freq/core.txt24
1 files changed, 13 insertions, 11 deletions
diff --git a/Documentation/cpu-freq/core.txt b/Documentation/cpu-freq/core.txt
index 4bc7287806de..978463a7c81e 100644
--- a/Documentation/cpu-freq/core.txt
+++ b/Documentation/cpu-freq/core.txt
@@ -8,6 +8,8 @@
Dominik Brodowski <linux@brodo.de>
David Kimdon <dwhedon@debian.org>
+ Rafael J. Wysocki <rafael.j.wysocki@intel.com>
+ Viresh Kumar <viresh.kumar@linaro.org>
@@ -36,10 +38,11 @@ speed limits (like LCD drivers on ARM architecture). Additionally, the
kernel "constant" loops_per_jiffy is updated on frequency changes
here.
-Reference counting is done by cpufreq_get_cpu and cpufreq_put_cpu,
-which make sure that the cpufreq processor driver is correctly
-registered with the core, and will not be unloaded until
-cpufreq_put_cpu is called.
+Reference counting of the cpufreq policies is done by cpufreq_cpu_get
+and cpufreq_cpu_put, which make sure that the cpufreq driver is
+correctly registered with the core, and will not be unloaded until
+cpufreq_put_cpu is called. That also ensures that the respective cpufreq
+policy doesn't get freed while being used.
2. CPUFreq notifiers
====================
@@ -69,18 +72,16 @@ CPUFreq policy notifier is called twice for a policy transition:
The phase is specified in the second argument to the notifier.
The third argument, a void *pointer, points to a struct cpufreq_policy
-consisting of five values: cpu, min, max, policy and max_cpu_freq. min
-and max are the lower and upper frequencies (in kHz) of the new
-policy, policy the new policy, cpu the number of the affected CPU; and
-max_cpu_freq the maximum supported CPU frequency. This value is given
-for informational purposes only.
+consisting of several values, including min, max (the lower and upper
+frequencies (in kHz) of the new policy).
2.2 CPUFreq transition notifiers
--------------------------------
-These are notified twice when the CPUfreq driver switches the CPU core
-frequency and this change has any external implications.
+These are notified twice for each online CPU in the policy, when the
+CPUfreq driver switches the CPU core frequency and this change has no
+any external implications.
The second argument specifies the phase - CPUFREQ_PRECHANGE or
CPUFREQ_POSTCHANGE.
@@ -90,6 +91,7 @@ values:
cpu - number of the affected CPU
old - old frequency
new - new frequency
+flags - flags of the cpufreq driver
3. CPUFreq Table Generation with Operating Performance Point (OPP)
==================================================================