On Fr, 2018-10-12 at 06:15 -0700, Tony Lindgren wrote:
Hi,
Would it increase power consumption a lot or probably not really noticeable?
It will increase the idle power consumption quite a bit AFAIK, this is a sign of something being broken for sure.
Okay, I now measured the power consumption and compared a 4GB unit with Self-Refresh disabled, the same unit with Self-Refresh enabled and a 2GB RAM unit (old mainboard and old CPU board).
And... well, either Idle / Self-Refresh is not working properly or there isn't really a difference yet.
Here's what I did:
1. Booted into the 4.19 kernel with only a basic set of modules enabled (so I had LEDs and the backlight of the LCD switched on).
2. Removed the battery after booting (so it was only being powered with USB). The USB cable had a USB measurement device inbetween.
3. Let the unit sit still for 10 minutes, measuring the power consumption.
The results:
2GB RAM unit: Varying between 1.9 - 2.1W (or 0.37 - 0.41A). 4GB RAM unit: Varying between 2.1 - 2.3W (or 0.41 - 0.47A).
So as expected, power consumption with the 4GB RAM unit is a bit higher. With a 22Wh battery as we have, the runtime difference in this case between the 2GB RAM unit and the 4GB would be around an hour (11 hours with the 2GB RAM and 10 hours with the 4GB RAM). Of course, it might change when the RAM is actually used :)
However, I didn't have ANY difference betwen the MLO / U-Boot with Self-Refresh enabled or disabled.
No idea why though...