1. DSP voltage boost is applied ONLY if DSP is active and overclocked
2. There is a /sys/power variable for adjusting boost voltage, called "sr_vdd1_dsp_boost". Its value is used in the following (pseudo)formula to calculate what voltage to be applied on top of what SR has already calculated:

dsp_volt_boost = ( DSP_FREQ(vdd1_opp) - 430 ) * sr_vdd1_dsp_boost * (VDD1_OPP9-vdd1_opp)

The above formula calculates boost voltage in uV. Default for sr_vdd1_dsp_boost is 125, and it could be changed between 0 and 250. There is a limit of 100mV for voltage boost.

Using the above one can choose whether to move DSP overclocking frequencies to higher MPU frequencies, or to adjust voltage when DSP is active (and overclocked above 430).