@willy I found another funny PVTM example (part of sbc-bench results collection): http://ix.io/47IO
cpu cpu0: pvtm=1436
cpu cpu0: pvtm-volt-sel=2
cpu cpu4: pvtm=1649
cpu cpu4: pvtm-volt-sel=3
cpu cpu6: pvtm=1662
cpu cpu6: pvtm-volt-sel=3
For whatever reasons highest cpufreq OPP is 2352 (maybe configured manually by tweaking DT) but this results in some MCU declining high clockspeeds totally and limiting the upper end to below 400 MHz 
Cpufreq OPP: 2352 Measured: 394 (394.973/394.794/394.738) (-83.2%)
Cpufreq OPP: 2208 Measured: 2099 (2099.382/2099.360/2099.164) (-4.9%)
Cpufreq OPP: 2016 Measured: 1975 (1975.674/1975.674/1975.239) (-2.0%)
Cpufreq OPP: 1800 Measured: 1803 (1803.289/1803.269/1803.208)
Cpufreq OPP: 1608 Measured: 1601 (1601.416/1601.377/1601.277)
Cpufreq OPP: 1416 Measured: 1436 (1436.630/1436.454/1436.326) (+1.4%)
Cpufreq OPP: 1200 Measured: 1183 (1184.341/1184.246/1183.392) (-1.4%)
Cpufreq OPP: 1008 Measured: 967 (967.415/967.324/967.166) (-4.1%)
Cpufreq OPP: 816 Measured: 778 (778.755/778.746/778.719) (-4.7%)
Cpufreq OPP: 600 Measured: 592 (592.871/592.725/592.632) (-1.3%)
Cpufreq OPP: 408 Measured: 394 (394.987/394.955/394.844) (-3.4%)
PVTM at work 