Missing brightness control on LM 18.3 for desktop with dual graphics hardware

[FanOfLinux]

I have a unique situation with two graphics devices on board for the desktop:

$ lspci | grep VGA
21:00.0 VGA compatible controller: NVIDIA Corporation GP102 [TITAN Xp] (rev a1)
42:00.0 VGA compatible controller: ASPEED Technology, Inc. ASPEED Graphics Family (rev 41)

Normally I would see brightness control when I clicked the battery icon in the taskbar.
But it is missing. I suspect it is partly due to two graphics devices I have.

I normally use the NVidia graphics card for display.
What is the default graphics app to install for brightness control,
and how do you deal with dual graphics chip devices as in my case?

Thank you.