[display] Add automatic cpu governor policy

MCE has cpu scaling governor feature that was meant to be used for
activating performance governor during bootup / shutdown and otherwise
select interactive governor. It was never taken in active use as is
was found to interfere with more advanced already existing android
side services. However - after fixing some obvious faults - having such
feature available might be useful for some device ports.

Make it possible to configure the following governor modes:
- performance - maximum performance
- interactive - high performance
- inactive    - medium performance
- powersave   - low performance

Implement policy that switches active governor based on device
state.

Utilize a run-time setting for:
- disabling the whole feature
- explicitly selecting one of the modes
- automatically switching between the modes depending on device state

Also provide:
- an annotated example configuration file
- python script for generating skeleton configuration files

Signed-off-by: Simo Piiroinen <[email protected]>

inifiles/cpu-governor.ini

@@ -0,0 +1,63 @@
+# Configuration file for MCE - CPU Governor control data
+#
+# Having configuration is completely optional.
+#
+# Also note that defining a configuration might not work
+# as expected for example when:
+# - there is some other daemon adjusting frequencies
+#   (adjustments get overridden / otherwise out of sync)
+# - sysfs control files appear/disapper dynamically
+#   (configured files do not exist when they would be written to)
+#
+# The mode can be selected explicitly or automatically based
+# on device state
+#
+#   mcetool --set-cpu-scaling-governor=<mode>
+#
+# Where mode is one of:
+# - disabled    - The feature is disabled
+# - performance - "Default" configuration is applied
+# - interactive - "Interactive" configuration is applied
+# - inactive    - "Inactive" configuration is applied
+# - idle        - "Idle" configuration is applied
+# - automatic   - Configuration is selected based on device state
+
+# "Default" values are applied when:
+# - device is booting up / shutting down
+# - mce is starting up / about to exit
+[CPUScalingGovernorDefault]
+path1=/sys/devices/system/cpu/cpu*/cpufreq/scaling_min_freq
+data1=432000
+
+# Up to 32 path/data pairs can be defined. Writing is done
+# in the given order. Each block is handled as-defined, i.e.
+# if it is somehow benefitial they can have different sets
+# of files to write to.
+#path2=xxx
+#data2=yyy
+# :
+#path32=xxx
+#data32=yyy
+
+# When the "Default" is not enforced, other values can be
+# either selected explicitly, or automatically based on
+# device state.
+
+# In automatic mode "Interactive" values are applied when:
+# - display is on and there is user activity
+# - during display power up / down
+[CPUScalingGovernorInteractive]
+path1=/sys/devices/system/cpu/cpu*/cpufreq/scaling_min_freq
+data1=432000
+
+# In automatic mode "Inactive" values are applied when:
+# - display is on and there is no user activity
+[CPUScalingGovernorInactive]
+path1=/sys/devices/system/cpu/cpu*/cpufreq/scaling_min_freq
+data1=384000
+
+# In automatic mode "Idle" values are applied when:
+# - display is off
+[CPUScalingGovernorIdle]
+path1=/sys/devices/system/cpu/cpu*/cpufreq/scaling_min_freq
+data1=216000