Documentation/ABI/testing/sysfs-class-devfreq

   1 What:           /sys/class/devfreq/.../
   2 Date:           September 2011
   3 Contact:        MyungJoo Ham <[email protected]>
   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 <[email protected]>
  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 <[email protected]>
  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 <[email protected]>
  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 <[email protected]>
  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/.../trans_stat
  41 Date:           October 2012
  42 Contact:        MyungJoo Ham <[email protected]>
  43 Description:
  44                 This ABI shows or clears the statistics of devfreq behavior
  45                 on a specific device. It shows the time spent in each state
  46                 and the number of transitions between states.
  47                 In order to activate this ABI, the devfreq target device
  48                 driver should provide the list of available frequencies
  49                 with its profile. If need to reset the statistics of devfreq
  50                 behavior on a specific device, enter 0(zero) to 'trans_stat'
  51                 as following::
  52
  53                         echo 0 > /sys/class/devfreq/.../trans_stat
  54
  55                 If the transition table is bigger than PAGE_SIZE, reading
  56                 this will return an -EFBIG error.
  57
  58 What:           /sys/class/devfreq/.../available_frequencies
  59 Date:           October 2012
  60 Contact:        Nishanth Menon <[email protected]>
  61 Description:
  62                 The /sys/class/devfreq/.../available_frequencies shows
  63                 the available frequencies of the corresponding devfreq object.
  64                 This is a snapshot of available frequencies and not limited
  65                 by the min/max frequency restrictions.
  66
  67 What:           /sys/class/devfreq/.../available_governors
  68 Date:           October 2012
  69 Contact:        Nishanth Menon <[email protected]>
  70 Description:
  71                 The /sys/class/devfreq/.../available_governors shows
  72                 currently available governors in the system.
  73
  74 What:           /sys/class/devfreq/.../min_freq
  75 Date:           January 2013
  76 Contact:        MyungJoo Ham <[email protected]>
  77 Description:
  78                 The /sys/class/devfreq/.../min_freq shows and stores
  79                 the minimum frequency requested by users. It is 0 if
  80                 the user does not care. min_freq overrides the
  81                 frequency requested by governors.
  82
  83 What:           /sys/class/devfreq/.../max_freq
  84 Date:           January 2013
  85 Contact:        MyungJoo Ham <[email protected]>
  86 Description:
  87                 The /sys/class/devfreq/.../max_freq shows and stores
  88                 the maximum frequency requested by users. It is 0 if
  89                 the user does not care. max_freq overrides the
  90                 frequency requested by governors and min_freq.
  91                 The max_freq overrides min_freq because max_freq may be
  92                 used to throttle devices to avoid overheating.
  93
  94 What:           /sys/class/devfreq/.../polling_interval
  95 Date:           September 2011
  96 Contact:        MyungJoo Ham <[email protected]>
  97 Description:
  98                 The /sys/class/devfreq/.../polling_interval shows and sets
  99                 the requested polling interval of the corresponding devfreq
 100                 object. The values are represented in ms. If the value is
 101                 less than 1 jiffy, it is considered to be 0, which means
 102                 no polling. This value is meaningless if the governor is
 103                 not polling.
 104
 105                 A list of governors that support the node:
 106                 - simple_ondmenad
 107                 - tegra_actmon
 108
 109 What:           /sys/class/devfreq/.../userspace/set_freq
 110 Date:           September 2011
 111 Contact:        MyungJoo Ham <[email protected]>
 112 Description:
 113                 The /sys/class/devfreq/.../userspace/set_freq shows and
 114                 sets the requested frequency for the devfreq object if
 115                 userspace governor is in effect.
 116
 117                 A list of governors that support the node:
 118                 - userspace
 119
 120 What:           /sys/class/devfreq/.../timer
 121 Date:           July 2020
 122 Contact:        Chanwoo Choi <[email protected]>
 123 Description:
 124                 This ABI shows and stores the kind of work timer by users.
 125                 This work timer is used by devfreq workqueue in order to
 126                 monitor the device status such as utilization. The user
 127                 can change the work timer on runtime according to their demand
 128                 as following::
 129
 130                         echo deferrable > /sys/class/devfreq/.../timer
 131                         echo delayed > /sys/class/devfreq/.../timer
 132
 133                 A list of governors that support the node:
 134                 - simple_ondemand