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-rw-r--r--Documentation/cpu-freq/cpu-drivers.txt27
1 files changed, 18 insertions, 9 deletions
diff --git a/Documentation/cpu-freq/cpu-drivers.txt b/Documentation/cpu-freq/cpu-drivers.txt
index 40282e617913..8b1a4451422e 100644
--- a/Documentation/cpu-freq/cpu-drivers.txt
+++ b/Documentation/cpu-freq/cpu-drivers.txt
@@ -23,8 +23,8 @@ Contents:
1.1 Initialization
1.2 Per-CPU Initialization
1.3 verify
-1.4 target or setpolicy?
-1.5 target
+1.4 target/target_index or setpolicy?
+1.5 target/target_index
1.6 setpolicy
2. Frequency Table Helpers
@@ -56,7 +56,8 @@ cpufreq_driver.init - A pointer to the per-CPU initialization
cpufreq_driver.verify - A pointer to a "verification" function.
cpufreq_driver.setpolicy _or_
-cpufreq_driver.target - See below on the differences.
+cpufreq_driver.target/
+target_index - See below on the differences.
And optionally
@@ -66,7 +67,7 @@ cpufreq_driver.resume - A pointer to a per-CPU resume function
which is called with interrupts disabled
and _before_ the pre-suspend frequency
and/or policy is restored by a call to
- ->target or ->setpolicy.
+ ->target/target_index or ->setpolicy.
cpufreq_driver.attr - A pointer to a NULL-terminated list of
"struct freq_attr" which allow to
@@ -103,8 +104,8 @@ policy->governor must contain the "default policy" for
this CPU. A few moments later,
cpufreq_driver.verify and either
cpufreq_driver.setpolicy or
- cpufreq_driver.target is called with
- these values.
+ cpufreq_driver.target/target_index is called
+ with these values.
For setting some of these values (cpuinfo.min[max]_freq, policy->min[max]), the
frequency table helpers might be helpful. See the section 2 for more information
@@ -133,20 +134,28 @@ range) is within policy->min and policy->max. If necessary, increase
policy->max first, and only if this is no solution, decrease policy->min.
-1.4 target or setpolicy?
+1.4 target/target_index or setpolicy?
----------------------------
Most cpufreq drivers or even most cpu frequency scaling algorithms
only allow the CPU to be set to one frequency. For these, you use the
-->target call.
+->target/target_index call.
Some cpufreq-capable processors switch the frequency between certain
limits on their own. These shall use the ->setpolicy call
-1.4. target
+1.4. target/target_index
-------------
+The target_index call has two arguments: struct cpufreq_policy *policy,
+and unsigned int index (into the exposed frequency table).
+
+The CPUfreq driver must set the new frequency when called here. The
+actual frequency must be determined by freq_table[index].frequency.
+
+Deprecated:
+----------
The target call has three arguments: struct cpufreq_policy *policy,
unsigned int target_frequency, unsigned int relation.