| 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 |
| 135 | |
| 136 | What: /sys/class/devfreq/.../related_cpus |
| 137 | Date: June 2025 |
| 138 | Contact: Linux power management list <[email protected]> |
| 139 | Description: The list of CPUs whose performance is closely related to the |
| 140 | frequency of this devfreq domain. |
| 141 | |
| 142 | This file is only present if a specific devfreq device is |
| 143 | closely associated with a subset of CPUs. |