Link to  documentation:
https://dri.freedesktop.org/docs/drm/gpu/amdgpu.html#power-dpm-force-performance-level

Quote:
pp_od_clk_voltage

The amdgpu driver provides a sysfs API for adjusting the clocks and voltages in
each power level within a power state. The pp_od_clk_voltage is used for this.

< For Vega10 and previous ASICs >

Reading the file will display:

    a list of engine clock levels and voltages labeled OD_SCLK
    a list of memory clock levels and voltages labeled OD_MCLK
    a list of valid ranges for sclk, mclk, and voltage labeled OD_RANGE

To manually adjust these settings, first select manual using
power_dpm_force_performance_level. ...