Documentation/ABI/testing/sysfs-class-devfreq

   1 What:           /sys/class/devfreq/.../
   2 Date:           September 2011
   3 Contact:        MyungJoo Ham <myungjoo.ham@samsung.com>
   4 Description:
   5                 Provide a place in sysfs for the devfreq objects.
   6                 This allows accessing various devfreq specific variables.
   7                 The name of devfreq object denoted as ... is same as the
   8                 name of device using devfreq.
   9
  10 What:           /sys/class/devfreq/.../name
  11 Date:           November 2019
  12 Contact:        Chanwoo Choi <cw00.choi@samsung.com>
  13 Description:
  14                 The /sys/class/devfreq/.../name shows the name of device
  15                 of the corresponding devfreq object.
  16
  17 What:           /sys/class/devfreq/.../governor
  18 Date:           September 2011
  19 Contact:        MyungJoo Ham <myungjoo.ham@samsung.com>
  20 Description:
  21                 The /sys/class/devfreq/.../governor show or set the name of the
  22                 governor used by the corresponding devfreq object.
  23
  24 What:           /sys/class/devfreq/.../cur_freq
  25 Date:           September 2011
  26 Contact:        MyungJoo Ham <myungjoo.ham@samsung.com>
  27 Description:
  28                 The /sys/class/devfreq/.../cur_freq shows the current
  29                 frequency of the corresponding devfreq object. Same as
  30                 target_freq when get_cur_freq() is not implemented by
  31                 devfreq driver.
  32
  33 What:           /sys/class/devfreq/.../target_freq
  34 Date:           September 2012
  35 Contact:        Rajagopal Venkat <rajagopal.venkat@linaro.org>
  36 Description:
  37                 The /sys/class/devfreq/.../target_freq shows the next governor
  38                 predicted target frequency of the corresponding devfreq object.
  39
  40 What:           /sys/class/devfreq/.../polling_interval
  41 Date:           September 2011
  42 Contact:        MyungJoo Ham <myungjoo.ham@samsung.com>
  43 Description:
  44                 The /sys/class/devfreq/.../polling_interval shows and sets
  45                 the requested polling interval of the corresponding devfreq
  46                 object. The values are represented in ms. If the value is
  47                 less than 1 jiffy, it is considered to be 0, which means
  48                 no polling. This value is meaningless if the governor is
  49                 not polling; thus. If the governor is not using
  50                 devfreq-provided central polling
  51                 (/sys/class/devfreq/.../central_polling is 0), this value
  52                 may be useless.
  53
  54 What:           /sys/class/devfreq/.../trans_stat
  55 Date:           October 2012
  56 Contact:        MyungJoo Ham <myungjoo.ham@samsung.com>
  57 Description:
  58                 This ABI shows or clears the statistics of devfreq behavior
  59                 on a specific device. It shows the time spent in each state
  60                 and the number of transitions between states.
  61                 In order to activate this ABI, the devfreq target device
  62                 driver should provide the list of available frequencies
  63                 with its profile. If need to reset the statistics of devfreq
  64                 behavior on a specific device, enter 0(zero) to 'trans_stat'
  65                 as following::
  66
  67                         echo 0 > /sys/class/devfreq/.../trans_stat
  68
  69 What:           /sys/class/devfreq/.../userspace/set_freq
  70 Date:           September 2011
  71 Contact:        MyungJoo Ham <myungjoo.ham@samsung.com>
  72 Description:
  73                 The /sys/class/devfreq/.../userspace/set_freq shows and
  74                 sets the requested frequency for the devfreq object if
  75                 userspace governor is in effect.
  76
  77 What:           /sys/class/devfreq/.../available_frequencies
  78 Date:           October 2012
  79 Contact:        Nishanth Menon <nm@ti.com>
  80 Description:
  81                 The /sys/class/devfreq/.../available_frequencies shows
  82                 the available frequencies of the corresponding devfreq object.
  83                 This is a snapshot of available frequencies and not limited
  84                 by the min/max frequency restrictions.
  85
  86 What:           /sys/class/devfreq/.../available_governors
  87 Date:           October 2012
  88 Contact:        Nishanth Menon <nm@ti.com>
  89 Description:
  90                 The /sys/class/devfreq/.../available_governors shows
  91                 currently available governors in the system.
  92
  93 What:           /sys/class/devfreq/.../min_freq
  94 Date:           January 2013
  95 Contact:        MyungJoo Ham <myungjoo.ham@samsung.com>
  96 Description:
  97                 The /sys/class/devfreq/.../min_freq shows and stores
  98                 the minimum frequency requested by users. It is 0 if
  99                 the user does not care. min_freq overrides the
 100                 frequency requested by governors.
 101
 102 What:           /sys/class/devfreq/.../max_freq
 103 Date:           January 2013
 104 Contact:        MyungJoo Ham <myungjoo.ham@samsung.com>
 105 Description:
 106                 The /sys/class/devfreq/.../max_freq shows and stores
 107                 the maximum frequency requested by users. It is 0 if
 108                 the user does not care. max_freq overrides the
 109                 frequency requested by governors and min_freq.
 110                 The max_freq overrides min_freq because max_freq may be
 111                 used to throttle devices to avoid overheating.
 112
 113 What:           /sys/class/devfreq/.../timer
 114 Date:           July 2020
 115 Contact:        Chanwoo Choi <cw00.choi@samsung.com>
 116 Description:
 117                 This ABI shows and stores the kind of work timer by users.
 118                 This work timer is used by devfreq workqueue in order to
 119                 monitor the device status such as utilization. The user
 120                 can change the work timer on runtime according to their demand
 121                 as following::
 122
 123                         echo deferrable > /sys/class/devfreq/.../timer
 124                         echo delayed > /sys/class/devfreq/.../timer