Linux kernel modesetting driver for Grain Media GM12U320 based devices
(primarily Acer C120 projector, but there may be compatible devices).

This is based on the fb driver from Viacheslav Nurmekhamitov:
https://github.com/slavrn/gm12u320

This driver supports PRIME, allowing the projector to be setup as a slave
output of your main gpu using xrandr --listproviders and
xrandr --setprovideroutputsource. After which the projector can be used as
a second monitor using your desktop environment config panel to select
clone or second monitor mode. HW 3d rendering is supported and will use the
main gpu and the rendered images will then be send to the projector via dma.

Installation:

make
sudo make modules_install
sudo depmod -a

The gm12u320 represents itself to the system as an usb-storage device, to
avoid the usb-storage driver grabbing the device before the gm12u320 driver
can bind to it, add "usb-storage.quirks=1de1:c102:i" to your kernel cmdline.

Reboot so that the new kernel cmdline is used, all done.