Nvidia drivers screen brightness and back light

[blubee blubeeme]

Hi

I am trying to tune this device a bit to be able to control the back light
/ screen brightness of the screen.

Here's the info on my GPU

vgapci0 at pci0:1:0:0: class=0x030000 card=0x0130106b chip=0x0fe910de rev=0xa1
hdr=0x00

    vendor     = 'NVIDIA Corporation'

    device     = 'GK107M [GeForce GT 750M Mac Edition]'

    class      = display

    subclass   = VGA

    cap 01[60] = powerspec 3  supports D0 D3  current D0

    cap 05[68] = MSI supports 1 message, 64 bit enabled with 1 message

    cap 10[78] = PCI-Express 2 endpoint max data 256(256) RO NS

                 link x8(x16) speed 8.0(8.0) ASPM L0s/L1(L0s/L1)

    cap 09[b4] = vendor (length 20)

    ecap 0002[100] = VC 1 max VC0

    ecap 0004[128] = Power Budgeting 1

    ecap 0001[420] = AER 2 0 fatal 0 non-fatal 0 corrected

    ecap 000b[600] = Vendor 1 ID 1

    ecap 0019[900] = PCIe Sec 1 lane errors 0


Here is the acpi information for this machine : http://paste2.org/LUcIwtzn

I came from running linux and typically there's a video or some acpi
settings that will control the brightness of the screen but on FreeBSD,
there doesn't seem to be anything like this so my monitor is constantly at
100% brightness. Shouldn't there be some way to dim the brightness through
the acpi interface?

Can I get some support to be able to dim the screen brightness?

Here is the output of my xorg.conf

# nvidia-xconfig: X configuration file generated by nvidia-xconfig

# nvidia-xconfig:  version 367.35  Wed Sep  7 17:03:49 CST 2016


Section "ServerLayout"

    Identifier     "Layout0"

    Screen      0  "Screen0"

    InputDevice    "Keyboard0" "CoreKeyboard"

    InputDevice    "Mouse0" "CorePointer"

EndSection


Section "Files"

EndSection


Section "InputDevice"

    # generated from default

    Identifier     "Mouse0"

    Driver         "mouse"

    Option         "Protocol" "auto"

    Option         "Device" "/dev/sysmouse"

    Option         "Emulate3Buttons" "no"

    Option         "ZAxisMapping" "4 5"

EndSection


Section "InputDevice"

    # generated from default

    Identifier     "Keyboard0"

    Driver         "keyboard"

EndSection


Section "Monitor"

    Identifier     "Monitor0"

    VendorName     "Unknown"

    ModelName      "Unknown"

    HorizSync       28.0 - 33.0

    VertRefresh     43.0 - 72.0

    Option         "DPMS"

EndSection


Section "Device"

    Identifier     "Device0"

    Driver         "nvidia"

    VendorName     "NVIDIA Corporation"

EndSection


Section "Screen"

    Identifier     "Screen0"

    Device         "Device0"

    Monitor        "Monitor0"

    DefaultDepth    24

    SubSection     "Display"

        Depth       24

    EndSubSection

EndSection


I use redshift and passing redshift -t x:x -b[0.0-1.0] allows some
brightness controls but then xrandr has to warm up and go from a cool color
screen to a warmer color then it adjusts the brightness.


There's also xrandr --ouput ACTIVE_DEVICE -brightness [0.0-1.0] this seems
to work but it won't work while redshift is working. They seem to fight for
control of the display then redshift takes control and the screen goes back
to somewhat full brightness.


Is there a more efficient way to control the screen brightness?