mfd: dt-bindings: Add RK818 device tree bindings document

[firefly-linux-kernel-4.4.55.git] / Documentation / cpu-freq / cpu-drivers.txt

diff --git a/Documentation/cpu-freq/cpu-drivers.txt b/Documentation/cpu-freq/cpu-drivers.txt
index b045fe54986a077792c80e4ad2563b2e38118a86..14f4e6336d88b7eab800163a665c38e34bdd7bb3 100644 (file)
--- a/Documentation/cpu-freq/cpu-drivers.txt
+++ b/Documentation/cpu-freq/cpu-drivers.txt
@@ -26,6 +26,7 @@ Contents:
 1.4  target/target_index or setpolicy?
 1.5  target/target_index
 1.6  setpolicy
+1.7  get_intermediate and target_intermediate
 2.   Frequency Table Helpers
 
 
@@ -79,6 +80,10 @@ cpufreq_driver.attr -                A pointer to a NULL-terminated list of
                                "struct freq_attr" which allow to
                                export values to sysfs.
 
+cpufreq_driver.get_intermediate
+and target_intermediate                Used to switch to stable frequency while
+                               changing CPU frequency.
+
 
 1.2 Per-CPU Initialization
 --------------------------
@@ -151,7 +156,7 @@ Some cpufreq-capable processors switch the frequency between certain
 limits on their own. These shall use the ->setpolicy call
 
 
-1.4. target/target_index
+1.5. target/target_index
 -------------
 
 The target_index call has two arguments: struct cpufreq_policy *policy,
@@ -160,6 +165,9 @@ 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.
 
+It should always restore to earlier frequency (i.e. policy->restore_freq) in
+case of errors, even if we switched to intermediate frequency earlier.
+
 Deprecated:
 ----------
 The target call has three arguments: struct cpufreq_policy *policy,
@@ -179,7 +187,7 @@ Here again the frequency table helper might assist you - see section 2
 for details.
 
 
-1.5 setpolicy
+1.6 setpolicy
 ---------------
 
 The setpolicy call only takes a struct cpufreq_policy *policy as
@@ -190,6 +198,23 @@ setting when policy->policy is CPUFREQ_POLICY_PERFORMANCE, and a
 powersaving-oriented setting when CPUFREQ_POLICY_POWERSAVE. Also check
 the reference implementation in drivers/cpufreq/longrun.c
 
+1.7 get_intermediate and target_intermediate
+--------------------------------------------
+
+Only for drivers with target_index() and CPUFREQ_ASYNC_NOTIFICATION unset.
+
+get_intermediate should return a stable intermediate frequency platform wants to
+switch to, and target_intermediate() should set CPU to to that frequency, before
+jumping to the frequency corresponding to 'index'. Core will take care of
+sending notifications and driver doesn't have to handle them in
+target_intermediate() or target_index().
+
+Drivers can return '0' from get_intermediate() in case they don't wish to switch
+to intermediate frequency for some target frequency. In that case core will
+directly call ->target_index().
+
+NOTE: ->target_index() should restore to policy->restore_freq in case of
+failures as core would send notifications for that.
 
 
 2. Frequency Table Helpers