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Old 2019-07-08, 09:11   #23
ldesnogu
 
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Quote:
Originally Posted by M344587487 View Post
powertop is worth a shot if it works, on my laptop it can disable controllers for USB, ethernet, SATA and other PCI devices.
I'm afraid powertop is Intel-only (not even AMD as far as I understand).
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Old 2019-07-08, 09:35   #24
M344587487
 
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Quote:
Originally Posted by ldesnogu View Post
I'm afraid powertop is Intel-only (not even AMD as far as I understand).
It started as an intel thing but that's the beauty of open source:
Quote:
PowerTOP is a software utility designed to measure, explain and minimise a computer's electrical power consumption. It was released by Intel in 2007 under the GPLv2 license. It works for Intel, AMD, ARM and UltraSPARC processors
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Old 2019-07-08, 10:01   #25
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Okay I assumed wrong earlier, that it's x86 and CPU only... Well, it happens to be available on that Gentoo 64-bit image, but unfortunately none of the Tunables make any difference to the current consumption.
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Old 2019-07-08, 10:28   #26
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If you don't mind feeling around in the dark you could try a modified version of a suggestion from here: https://stackoverflow.com/questions/...n-raspberry-pi

Namely:
Quote:
Disabling an ethernet interface actually doesn't power down the hardware. You have to disable the chip via bus power. But I'm afraid, that the same chip which contains the ethernet driver also contains the USB driver.
See this question on raspberrypi.stackexchange.com. There is different chip (LAN9512) discussed, but disabling it should be same. I just wonder why you have different chip, maybe different Raspberry Pi's revision?
So to power down the chip, just write 0 to the file /sys/devices/platform/bcm2708_usb/buspower:
If this even applies the pi4 will have different chips (and I assume they no longer have a unified USB/ethernet chip), so list the contents of /sys/devices/platform, figure out which are for ethernet, USB and whatever else is unnecessary and see if they can be disabled.
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Old 2019-07-08, 11:38   #27
nomead
 
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Quote:
Originally Posted by M344587487 View Post
If this even applies the pi4 will have different chips (and I assume they no longer have a unified USB/ethernet chip), so list the contents of /sys/devices/platform, figure out which are for ethernet, USB and whatever else is unnecessary and see if they can be disabled.
Yeah the Pi4 has Ethernet on the SoC now, and USB (and only USB) is handled by the external VL805 chip, that just got the firmware update. But anyway, poking around, I only found /sys/devices/platform/soc/fe980000.usb/buspower that I could write to, and writing a zero to it didn't have any effect on current consumption. So probably that isn't the VL805 but something else, then. There's supposed to be USB 2.0 functionality on the SoC so maybe that's it. Some other power controls only suspend 5V power to the USB ports if they're not in use. But again, maybe some things are not yet accessible in the kernel version that the Gentoo build is using. Let's see on the Raspbian side.

There's certainly extra stuff visible on Raspbian, under /sys/devices/platform/scb/fd500000.pcie/pci0000:00/0000:00:00.0/0000:01:00.0 but I think none of that applies either for disabling the whole module...
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