BananaPi Pro - Power Consumption

[WolfDonner]

Greetings,

after a long time I am playing with my old Banana Pi Pro again. This time with the intention to probably use it on IoT purposes. That implies I only need WIFI and the GPIO pins.

Which gives some opportunity to save power by powering down every thing else which is not needed.

My first approach here is to strip down everything from the device tree I don´t need. That means everything related to:

• framebuffer
• hdmi
• lcd
• sata
• display engine
• ethernet
• video codec
• usb
• ir
• gpu/mali

 

That resulted in a drop in power consumption in idle from: ~0.990 - ~1.330W

to: ~0.700 - ~1.000W

Roughly 0.3W lower consumption. Furthermore I underclocked the CPU to the minimum of 144MHz with power save governor.

Resulting in a idle power consumption of: ~0.670 - ~0.720W

 

I also tried setting the default kernel tick rate from 250HZ to 100HZ but that gave no measurable gains.

And just for curiosity I deactivated the WIFI from the device tree resulting in a consumption of: ~0.470 - ~0.520W

Thats pretty much for one needed component and I am asking myself if there is some saving potential here. So I found out from iwconfig that power management is not enabled. Enabling it by changing /etc/NetworkManager/conf.d/20-override-wifi-powersave-disable.conf wifi.powersave from 2 to 3 changed what iwconfig shows. But it has no influence on power consumption at all.

 

So my questions here are the following:

1. Is there a possibility to save power on wifi?
2. Are there other things I can do aside from these I have done?

 

[arox]

"Are there other things I can do aside from these I have done?"

 

Lowering DRAM refresh rate was the most efficient powersaving trick. But I don't know if and how it can be done with modern kernel ?

 

https://github.com/armbian/build/blob/master/packages/bsp/h3consumption

[Werner]

Some of those things might still work but by adjusting manually and not within the script since that -  as correctly guessed -  was written for legacy 3.x kernels and rely on fex rather than modern dtb.

[WolfDonner]

I tried to lower the DRAM clock by setting

CONFIG_DRAM_CLK=240

in the kernel config. Sadly this did not make a difference.

 

Still I am thinking about to maybe get something out of the wifi. I do not need it at full speed. 10MBits would be totally enough.

Setting Tx-Power with iwconfig also made no difference. And Bit Rate was not settable at all.

Maybe I could fall back to use only b/g wifi and deactivate n. Is that possible?