Vim3 USB Power

Ruby Zhuang

unread,

Mar 5, 2021, 2:03:01 PM3/5/21

to drive...@fuchsia.dev

Hi everyone!

TLDR; If you're developing on Vim3, make sure the USB port supplying power to your Vim3 can draw up to 24 W.

I recently enabled DVFS on Vim3, which may cause the device to draw more power (up to 24 W) while under heavy load. If you are bus-powering your VIM3 from a USB-A port, ensure the port can supply up to 24W of power (or up to 4.8A of drive current). Otherwise, you can disable DVFS (and the temperature sensors) by commenting out ThermalInit() here: https://cs.opensource.google/fuchsia/fuchsia/+/master:src/devices/board/drivers/vim3/vim3.cc;l=137

Thanks,
Ruby

Suraj Malhotra

unread,

Mar 5, 2021, 2:20:57 PM3/5/21

to Ruby Zhuang, drive...@fuchsia.dev

If we expect some folks to necessarily disable this feature often, we should consider adding a GN arg to do it or a kernel arg, rather than have folks modify the source.

What is the expected maximum power draw with DVFS disabled? Also I've noticed we don't have a vim3 page on fuchsia.dev, should we add one and note this information on it so it doesn't get lost in the void?

--
All posts must follow the Fuchsia Code of Conduct https://fuchsia.dev/fuchsia-src/CODE_OF_CONDUCT or may be removed.
---
You received this message because you are subscribed to the Google Groups "drivers-dev" group.
To unsubscribe from this group and stop receiving emails from it, send an email to drivers-dev...@fuchsia.dev.
To view this discussion on the web visit https://groups.google.com/a/fuchsia.dev/d/msgid/drivers-dev/CAMiNcDoOmKM3aSJpRhgr_GoQK-LWgCk5NBrmajzdsmJ_3LDtjQ%40mail.gmail.com.

Sam Hansen

unread,

Mar 5, 2021, 2:22:53 PM3/5/21

to Suraj Malhotra, Ruby Zhuang, drive...@fuchsia.dev

Prior to the DVFS stuff, I had been powering the board from a 900mA
hub port without issue. I'm unsure of what the out-of-reset power
profile is though.

> To view this discussion on the web visit https://groups.google.com/a/fuchsia.dev/d/msgid/drivers-dev/CAFFy6-C-z9WvSHqbODQ8wmTrN4szKGGRhjMGxGKWPCW%3Du7Czyg%40mail.gmail.com.

Curtis Galloway

unread,

Mar 5, 2021, 2:52:32 PM3/5/21

to Sam Hansen, Suraj Malhotra, Ruby Zhuang, drive...@fuchsia.dev

The VIM3 can detect the characteristics of the power supply I believe, so I think this is an interesting use case for figuring out how to propagate that information through our power management system appropriately. This is getting more common so will be a good pattern to support.

I captured this in fxb/71610 – Ruby, could you do a little research on how the power interface works?

--Curtis

To view this discussion on the web visit https://groups.google.com/a/fuchsia.dev/d/msgid/drivers-dev/CAP9bUy7MegfVcj1-BTFk%2BcDOTRrz_B2_X2TTjcqOu87u7FPWcw%40mail.gmail.com.

Ruby Zhuang

unread,

Mar 5, 2021, 2:59:48 PM3/5/21

to Curtis Galloway, Sam Hansen, Suraj Malhotra, drive...@fuchsia.dev

Ok! Will look into it. And figure out how to add a GN arg!

Allan MacKinnon

unread,

Mar 5, 2021, 3:07:57 PM3/5/21

to Ruby Zhuang, Curtis Galloway, Sam Hansen, Suraj Malhotra, drive...@fuchsia.dev

Just in case it was missed, I saw Khadas made some changes in V13 of the VIM3 (Nov. 2020):

https://www.khadas.com/post/vim3-v13-whats-new

To view this discussion on the web visit https://groups.google.com/a/fuchsia.dev/d/msgid/drivers-dev/CAMiNcDoOa-DeimqBmfdi-mcPtFja9tR1mOCRWUqmk%3DSUOH2n0g%40mail.gmail.com.

Message has been deleted

Curtis Galloway

unread,

May 1, 2021, 12:42:42 PM5/1/21

to drivers-dev, Allan MacKinnon, Curtis Galloway, Sam Hansen, Suraj Malhotra, drive...@fuchsia.dev, Ruby Zhuang

Looks like they increased the USB port current and fixed the problem of blowing up the board if you connect both VIN and USB. Ruby, you might want to get a few v13 boards for comparison. --Curtis

Reply all

Reply to author

Forward