This small command line utility allows for changing the brightness of one or more Apple Studio Display(s) attached to a Linux or Windows PC.
Tool to get or set the brightness for Apple Studio Displays Usage: asdbctl [OPTIONS] <COMMAND> Commands: get Get the current brightness in % set Set the current brightness in % up Increase the brightness down Decrease the brightness help Print this message or the help of the given subcommand(s) Options: -s, --serial <SERIAL> Serial number of the display for which to adjust the brightness -h, --help Print help
Prebuild releases are not available. Only Rust is required to build from source.
git clone https://github.com/juliuszint/asdbctl.git && cd asdbctl
# either just run from here
cargo run --release -- help
# or install with
cargo install --path .In case regular users are not allowed to access raw HID devices, you can use the udev rule in the rules.d directory.
Dumping the USB traffic on macOS with Wireshark and setting the proper filters will show the USB Control transfers to set the brightness
bmRequestType: 0x21 bRequest : 0x9 wValue : 0x0301 wIndex: : 0x000c wLength : 0x7
with this data package when setting it to the minimum brightness value
[ 0x01, 0x90, 0x01, 0x00, 0x00, 0x00, 0x00 ]
The 0x90 and 0x01 are the brightness value encoded with the least
significant byte first (LSB).
Its possible to operate the Studio Display in 3 different USB configurations
and Linux will use the first. This means that the USB interface number for
controlling the brightness is not 0xc (extracted from the dump) but 0x7.
Apple Studio Display HID report descriptor # device 0:0 # 0x05, 0x80, // Usage Page (Monitor) 0 # 0x09, 0x01, // Usage (Monitor Control) 2 # 0xa1, 0x01, // Collection (Application) 4 # 0x85, 0x01, // Report ID (1) 6 # 0x06, 0x82, 0x00, // Usage Page (VESA Virtual Controls) 8 # 0x09, 0x10, // Usage (Brightness) 11 # 0x16, 0x90, 0x01, // Logical Minimum (400) 13 # 0x27, 0x60, 0xea, 0x00, 0x00, // Logical Maximum (60000) 16 # 0x67, 0xe1, 0x00, 0x00, 0x01, // Unit (SILinear: cm⁻² * cd) 21 # 0x55, 0x0e, // Unit Exponent (-2) 26 # 0x75, 0x20, // Report Size (32) 28 # 0x95, 0x01, // Report Count (1) 30 # 0xb1, 0x42, // Feature (Data,Var,Abs,Null) 32 # 0x05, 0x0f, // Usage Page (Vendor Usage Page 0x0f) 34 # 0x09, 0x50, // Usage (Vendor Usage 0x50) 36 # 0x15, 0x00, // Logical Minimum (0) 38 # 0x26, 0x20, 0x4e, // Logical Maximum (20000) 40 # 0x66, 0x10, 0x01, // Unit (None) 43 # 0x55, 0x0d, // Unit Exponent (-3) 46 # 0x75, 0x10, // Report Size (16) 48 # 0xb1, 0x42, // Feature (Data,Var,Abs,Null) 50 # 0x06, 0x82, 0x00, // Usage Page (VESA Virtual Controls) 52 # 0x09, 0x10, // Usage (Brightness) 55 # 0x16, 0x90, 0x01, // Logical Minimum (400) 57 # 0x27, 0x60, 0xea, 0x00, 0x00, // Logical Maximum (60000) 60 # 0x67, 0xe1, 0x00, 0x00, 0x01, // Unit (SILinear: cm⁻² * cd) 65 # 0x55, 0x0e, // Unit Exponent (-2) 70 # 0x75, 0x20, // Report Size (32) 72 # 0x95, 0x01, // Report Count (1) 74 # 0x81, 0x02, // Input (Data,Var,Abs) 76 # 0xc0, // End Collection 78 R: 79 05 80 09 01 a1 01 85 01 06 82 00 09 10 16 90 01 27 60 ea 00 00 67 e1 00 00 01 55 0e 75 20 95 01 b1 42 05 0f 09 50 15 00 26 20 4e 66 10 01 55 0d 75 10 b1 42 06 82 00 09 10 16 90 01 27 60 ea 00 00 67 e1 00 00 01 55 0e 75 20 95 01 81 02 c0 N: device 0:0 I: 3 0001 0001
Other projects that helped along the way were LG-ultrafine-brightness and acdcontrol.