Power management on rock 5b

[Merblud]

Greetings to the happy owners of the rock 5b. Tell me if the rock 5b turns off the power to all its components when shutting down. I understand that the power from the external power supply is still being supplied. And what happens to the devices on the board: ssd, fan, wifi etc.

[gounthar]

I have no idea unfortunately.
But this board is finicky when it comes to power...
It worked well with a dummy 5V power supply for me, and even with my PinePower WC3.0 port.
I then added an NVME, and since then, it does not want to boot anymore, with or without NVME...

[specs]

PD has advantages when you use the cables at 2A for a long time. But that is typically for charging a phone or a laptop in a short time.

 

With a PD-adapter the power consumption is pretty bad for the Rock5.

With a constant Voltage power supply it is only bad in combination with NVMe and good in combination with eMMC.

When powered of, without removing the power cable, the Rock5B still uses about 0,5W (slightly worse than a RPI4, which is already bad).

 

When using eMMC the Rock5B uses about 1.8-2W in idle. When you are using a general 30-65W PD adapter make it 2.4-3W in idle (the DC-DC conversion from  20V to 5V is very inefficient, if you have a small and cheap PD adapter this adds to the  inefficiency).

 

When using an NVMe you could get the power consumption as low as 4W in idle, with a 12V constant voltage adapter.

CPU 0-3: 1200 ( 600 Mhz - 1800 MHz / conservative)
CPU 4-5:  816 ( 408 Mhz - 2400 MHz / conservative)
CPU 6-7:  600 ( 408 Mhz - 2400 MHz / conservative)
GPU    :  300 ( 300 Mhz - 1000 MHz / simple_ondemand)
DMC    : 1560 ( 528 Mhz - 1560 MHz / dmc_ondemand)

Here the pcie_aspm (NVMe connection) is set to powersupersave.

 

With the pcie_aspm set to performance and all the cpu and gpu settings to max you get 6W in idle.

CPU 0-3: 1800 (1800 Mhz - 1800 MHz / performance)
CPU 4-5: 2400 (1000 Mhz - 2400 MHz / performance)
CPU 6-7: 2400 (1000 Mhz - 2400 MHz / performance)
GPU    : 1000 ( 300 Mhz - 1000 MHz / performance)
DMC    : 2112 ( 528 Mhz - 2112 MHz / performance)

The Kingston A2000 might not be the most energie-efficient NVMe, but other brands generally also focus on performance instead of efficiency.

 

The above summary is made by parsing the settings from:
  /sys/devices/system/cpu/cpufreq/policyX/

  /sys/devices/platform/fb000000.gpu/devfreq/fb000000.gpu/

  /sys/devices/platform/dmc/devfreq/dmc/

  /sys/module/pcie_aspm/parameters/

(You can also use the sys-tree to quickly change the settings with a script).

 

Ondemand and conservative are generally similar for power consumption in idle mode.

 

Earlier experiences that low power consumption and NVMe are a bad combination is true for the Rock5 as well. PowerSuperSave can not be considered a stable option for all NVMe drives. But still with lowpower solutions NVMe might be preferable to eMMC since it is slightly better protected against data loss.

 

In performance mode, during a compilation, the consumption easily reaches 13W (with NVMe, without large USB users, without much GPU use).

(I use a cheap power supply with monitoring to get the general idea of power consumption, not a calibrated solution).

 

Finally you could use a constant power supply of 5V to lower the power consumption in idle. I would not recommend that , I think optimizing for 1.5A at peak performance is better, resulting in 9V or 12V for most cases. (Instead of PD, QC is probably cheaper and more power efficient).