1. 06 Sep, 2016 1 commit
  2. 30 Mar, 2015 1 commit
  3. 30 Jan, 2015 1 commit
    • Chanwoo Choi's avatar
      PM / devfreq: event: Add devfreq_event class · f262f28c
      Chanwoo Choi authored
      This patch adds a new class in devfreq, devfreq_event, which provides
      raw data (e.g., memory bus utilization, GPU utilization) for devfreq
      governors.
      
      - devfreq_event device : Provides raw data for a governor of a devfreq device
      - devfreq device       : Monitors device state and changes frequency/voltage
      			of the device using the raw data from its
      			devfreq_event device.
      
      A devfreq device dertermines performance states (normally the frequency
      and the voltage vlues) based on the results its designtated devfreq governor:
      e.g., ondemand, performance, powersave.
      
      In order to give such results required by a devfreq device, the devfreq
      governor requires data that indicates the performance requirement given
      to the devfreq device. The conventional (previous) implementatino of
      devfreq subsystem requires a devfreq device driver to implement its own
      mechanism to acquire performance requirement for its governor. However,
      there had been issues with such requirements:
      
      1. Although performance requirement of such devices is usually acquired
       from common devices (PMU/PPMU), we do not have any abstract structure to
       represent them properly.
      2. Such performance requirement devices (PMU/PPMU) are actual hardware
       pieces that may be represented by Device Tree directly while devfreq device
       itself is a virtual entity that are not considered to be represented by
       Device Tree according to Device Tree folks.
      
      In order to address such issues, a devferq_event device (represented by
      this patch) provides a template for device drivers representing
      performance monitoring unit, which gives the basic or raw data for
      preformance requirement, which in turn, is required by devfreq governors.
      
      The following description explains the feature of two kind of devfreq class:
      - devfreq class (existing)
       : devfreq consumer device use raw data from devfreq_event device for
         determining proper current system state and change voltage/frequency
         dynamically using various governors.
      
      - devfreq_event class (new)
       : Provide measured raw data to devfreq device for governor
      
      Cc: MyungJoo Ham <myungjoo.ham@samsung.com>
      Cc: Kyungmin Park <kyungmin.park@samsung.com>
      Signed-off-by: default avatarChanwoo Choi <cw00.choi@samsung.com>
      [Commit message rewritten & conflict resolved by MyungJoo]
      Signed-off-by: default avatarMyungJoo Ham <myungjoo.ham@samsung.com>
      f262f28c