Apply k4412 kernel from HardKernel for ODROID-X.

1 files changed, 38 insertions, 0 deletions

diff --git a/Documentation/cpu-freq/governors.txt b/Documentation/cpu-freq/governors.txt
index e74d0a2eb1c..51b1cd360c3 100644
--- a/Documentation/cpu-freq/governors.txt
+++ b/Documentation/cpu-freq/governors.txt
@@ -28,6 +28,7 @@ Contents:
 2.3  Userspace
 2.4  Ondemand
 2.5  Conservative
+2.6  Interactive
 
 3.   The Governor Interface in the CPUfreq Core
 
@@ -193,6 +194,43 @@ governor but for the opposite direction.  For example when set to its
 default value of '20' it means that if the CPU usage needs to be below
 20% between samples to have the frequency decreased.
 
+
+2.6 Interactive
+---------------
+
+The CPUfreq governor "interactive" is designed for latency-sensitive,
+interactive workloads. This governor sets the CPU speed depending on
+usage, similar to "ondemand" and "conservative" governors.  However,
+the governor is more aggressive about scaling the CPU speed up in
+response to CPU-intensive activity.
+
+Sampling the CPU load every X ms can lead to under-powering the CPU
+for X ms, leading to dropped frames, stuttering UI, etc.  Instead of
+sampling the cpu at a specified rate, the interactive governor will
+check whether to scale the cpu frequency up soon after coming out of
+idle.  When the cpu comes out of idle, a timer is configured to fire
+within 1-2 ticks.  If the cpu is very busy between exiting idle and
+when the timer fires then we assume the cpu is underpowered and ramp
+to MAX speed.
+
+If the cpu was not sufficiently busy to immediately ramp to MAX speed,
+then governor evaluates the cpu load since the last speed adjustment,
+choosing the highest value between that longer-term load or the
+short-term load since idle exit to determine the cpu speed to ramp to.
+
+The tuneable values for this governor are:
+
+min_sample_time: The minimum amount of time to spend at the current
+frequency before ramping down. This is to ensure that the governor has
+seen enough historic cpu load data to determine the appropriate
+workload.  Default is 80000 uS.
+
+go_maxspeed_load: The CPU load at which to ramp to max speed.  Default
+is 85.
+
+timer_rate: Sample rate for reevaluating cpu load when the system is
+not idle.  Default is 30000 uS.
+
 3. The Governor Interface in the CPUfreq Core
 =============================================