USB hierarchy

[Chris85]

Hi there,

I stumbled over something interresting:
Today I plugged an USB-HUB with 3 devices (joystick, thrust lever and pedals) into a free USB-Slot (USB2 or 3) of my mainboard (backside of the PC).
I also plugged my HP-Reverb G2 into another rear USB-C Port.

Now when starting my PC I cant get into the bios, as my keyboard doesnt get recognized by the system until Windows 11 starts. (My mouse and keyboard both are plugged into the monitor, which functions as USB-Hub that is plugged into one of the rear mainboard USB-Slots)
When unplugging either the VR Headset or the USB Hub with the 3 devices plugged into, I can enter the bios as my keyboard gets beeing recongnized while startup.

So is there some kind of like "USB-hierarchy" that defines which device should be plugged into which specific mainboard-USB-slot in order to be able to get into the bios without unplugging any device?

Edit: The USB-Hub is optionally powered by a power adapter - no matter if I power the hub with the power adapter or not- the outcome is like described above.

Cheers
Chris

 

[cvaldes]

USB hierarchy? Not to my knowledge. If there were, we would have been reading about it incessantly in PC Q&A forums for the past two decades.

I have a couple of PCs right now that can easily access the BIOS via a mouse and keyboard plugged into powered USB hubs. That said, every time I set up a new motherboard, I always plug wired mouse and keyboard directly into USB ports on the motherboard for the initial setup and Windows installation.

One thing I know from experience is that super cheap USB hubs can cause problems. So can USB hubs built into monitors. Therefore I don't plug in critical devices like mice and keyboards into the monitor USB ports and I won't buy cheapo hubs nor will I daisy chain mice and keyboards.

There were some versions of AMD's AGESA BIOS that had USB problems. (Use your favorite search engine to read about this, it was heavily covered by PC hardware media sites.) These problems were eliminated with later versions of the BIOS. You didn't bother to list your PC hardware configuration (that's what the System Specs feature is for) so there's no way to tell if this might be your problem.

Anyhow best of luck.

 

[ir_cow]

I've found certain USB ports are not active until past the boot sequence or until windows. Its becoming increasingly rare. What your seeing I believe is that USB port (probably more than one) is not connected directly to the USB or chipset. Instead a third-party chip like ASMedia. This is usually so a bunch of ports can share the same bandwidth. Which is technically cheating the specs since they won't all be able to run at maximum bandwidth at once. Without drivers, the chip does nothing and therefore cannot be used during the boot sequence.

That is my theory anyways. Like I said, its rare these days, but I've used my far share of pre-builts that function exactly as your describe. Also back about 20 years ago I ran into this problem as well.

 

[Chris85]

USB hierarchy? Not to my knowledge. If there were, we would have been reading about it incessantly in PC Q&A forums for the past two decades.

I have a couple of PCs right now that can easily access the BIOS via a mouse and keyboard plugged into powered USB hubs. That said, every time I set up a new motherboard, I always plug wired mouse and keyboard directly into USB ports on the motherboard for the initial setup and Windows installation.

One thing I know from experience is that super cheap USB hubs can cause problems. So can USB hubs built into monitors. Therefore I don't plug in critical devices like mice and keyboards into the monitor USB ports and I won't buy cheapo hubs nor will I daisy chain mice and keyboards.

There were some versions of AMD's AGESA BIOS that had USB problems. (Use your favorite search engine to read about this, it was heavily covered by PC hardware media sites.) These problems were eliminated with later versions of the BIOS. You didn't bother to list your PC hardware configuration (that's what the System Specs feature is for) so there's no way to tell if this might be your problem.

Anyhow best of luck.

Thank you,

I filled in the specs so that you guys should be able to see them now.

 

[qubit]

Plug the keyboard and mouse directly into the back of the PC and see if the problem goes away, then leave it like that. Plug in other, non-critical stuff into the monitor's USB ports.

 

[micropage7]

although it said universal, sometimes it blocks like when you try entering bios or any weird stuff, maybe you can check one by one. i agree if you connect any important peripheral straight to the board without using hub or any add on card or through monitor, then check one by one

 

[Chris85]

Here comes the update
I did some tests and I found this out:

1. Keyboard directly plugged to any usb port of the PC - no matter how many peripherals are plugged in I always can enter bios.
2. Initially my keyboard and mouse were plugged into the monitor that functioned as powered usb hub, that was plugged into a usb-splitter (to be able to switch mouse and keyboard between pc and PlayStation without replugging everything). With this setup I was not able to enter bios with the keyboard. But without the usb-splitter I was able to get into the bios.
3. When plugging the keyboard into another unpowered usb hub I was not able to enter bios

Conclusion:
No matter what setup I used, in windows the keyboard was always detected. Directly plugging the keyboard into the pc is the best way to ensure being able to enter the bios.
Powered switches seem also to do the job but not with any splitters in between.
I must confess that my setup seems a bit „special“ with these usb-hub/splitter connnections but maybe someone finds my research results helpful.

Cheers!
Chris