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                 If the transition table is bigger than PAGE_SIZE, reading
  70                 this will return an -EFBIG error.
  71
  72 What:           /sys/class/devfreq/.../userspace/set_freq
  73 Date:           September 2011
  74 Contact:        MyungJoo Ham <myungjoo.ham@samsung.com>
  75 Description:
  76                 The /sys/class/devfreq/.../userspace/set_freq shows and
  77                 sets the requested frequency for the devfreq object if
  78                 userspace governor is in effect.
  79
  80 What:           /sys/class/devfreq/.../available_frequencies
  81 Date:           October 2012
  82 Contact:        Nishanth Menon <nm@ti.com>
  83 Description:
  84                 The /sys/class/devfreq/.../available_frequencies shows
  85                 the available frequencies of the corresponding devfreq object.
  86                 This is a snapshot of available frequencies and not limited
  87                 by the min/max frequency restrictions.
  88
  89 What:           /sys/class/devfreq/.../available_governors
  90 Date:           October 2012
  91 Contact:        Nishanth Menon <nm@ti.com>
  92 Description:
  93                 The /sys/class/devfreq/.../available_governors shows
  94                 currently available governors in the system.
  95
  96 What:           /sys/class/devfreq/.../min_freq
  97 Date:           January 2013
  98 Contact:        MyungJoo Ham <myungjoo.ham@samsung.com>
  99 Description:
 100                 The /sys/class/devfreq/.../min_freq shows and stores
 101                 the minimum frequency requested by users. It is 0 if
 102                 the user does not care. min_freq overrides the
 103                 frequency requested by governors.
 104
 105 What:           /sys/class/devfreq/.../max_freq
 106 Date:           January 2013
 107 Contact:        MyungJoo Ham <myungjoo.ham@samsung.com>
 108 Description:
 109                 The /sys/class/devfreq/.../max_freq shows and stores
 110                 the maximum frequency requested by users. It is 0 if
 111                 the user does not care. max_freq overrides the
 112                 frequency requested by governors and min_freq.
 113                 The max_freq overrides min_freq because max_freq may be
 114                 used to throttle devices to avoid overheating.
 115
 116 What:           /sys/class/devfreq/.../timer
 117 Date:           July 2020
 118 Contact:        Chanwoo Choi <cw00.choi@samsung.com>
 119 Description:
 120                 This ABI shows and stores the kind of work timer by users.
 121                 This work timer is used by devfreq workqueue in order to
 122                 monitor the device status such as utilization. The user
 123                 can change the work timer on runtime according to their demand
 124                 as following::
 125
 126                         echo deferrable > /sys/class/devfreq/.../timer
 127                         echo delayed > /sys/class/devfreq/.../timer