They're still in the operating range according to i.MX 8M Quad datasheet. There's some headroom added over minimal values to account for voltage drop.
Operational ranges (min - typ - max [selected]):
- VDD_SOC (BUCK1): 0.81 - 0.9 - 0.99 [0.88]
- VDD_ARM (BUCK2): 0.81 - 0.9 - 1.05 [0.84] (1000MHz)
0.90 - 1.0 - 1.05 [0.93] (1500MHz)
- VDD_GPU (BUCK3): 0.81 - 0.9 - 1.05 [0.85] (800MHz)
0.90 - 1.0 - 1.05 [ -- ] (1000MHz)
- VDD_VPU (BUCK4): 0.81 - 0.9 - 1.05 [ -- ] (550/500/588MHz)
0.90 - 1.0 - 1.05 [0.93] (660/600/800MHz)Idle power consumption doesn't appear to be influenced much,
but a simple load test (cat /dev/urandom | pigz - > /dev/null
combined with running Animatch) seems to show about 0.3W of
difference.
Care is advised, as there may be differences between each units in how low can they be undervolted - in my experience, reaching that point usually makes the phone fail to boot. In my case, it appears that my Birch phone can go down the most.
This is a somewhat conservative set of values that I've seen working well on all my devices; I haven't tried very hard to optimize it, so more experiments are welcome.