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    Brightness

    Brightness control uses the kernel backlight interface by default. ddcutil support is opt-in for external monitors that expose DDC/CI brightness.

    [brightness]
    enable_ddcutil     = false
    ignore_mmids       = []     # e.g. ["ACI-ROG_PG279Q-10220"] - skip in all ddcutil commands
    minimum_brightness = 0.0    # never let brightness drop below this floor (0.0 to 1.0)
    sync_all_monitors = false   # if set to true, makes every display have the same brightness
    

    [brightness.monitor.eDP-1]
    backend = "backlight"   # auto | none | backlight | ddcutil
    backlight_device = "intel_backlight"   # explicit sysfs device name or path
    

    [brightness.monitor.DP-1]
    backend = "ddcutil"

    Notes:

    • enable_ddcutil = true only enables DDC/CI discovery - it does not force every monitor to ddcutil.
    • ignore_mmids passes --ignore-mmid to every ddcutil invocation. Run ddcutil --verbose detect to find monitor model id strings.
    • minimum_brightness is an opt-in floor (default 0.0 = disabled). Any brightness change is clamped to at least this value, and the control center slider cannot go below it - useful to keep the screen from going completely dark.
    • sync_all_monitors only syncs the brightnesses when one of the display brightnesses change, it does not actively sync them every now and then
    • Per-monitor overrides use the same connector/description matching rules as bar monitor overrides.
    • backend = "auto" prefers kernel backlight when available and falls back to ddcutil.
    • backend = "none" hides brightness control for the matched monitor.
    • backlight_device pins a monitor to a specific sysfs backlight device when a connector exposes more than one - accepts a bare name (intel_backlight) or a full path; run noctalia msg brightness-list-backlight-devices to list the available device names.
    • ddcutil is treated as best-effort - repeated DDC failures cool down that monitor to avoid hammering the bus.

    DDC/CI discovery runs in the background. If a monitor is not ready when Noctalia starts or outputs change, Noctalia retries discovery up to three times, waiting one, two, and four seconds after each completed attempt. Working brightness controls remain available while other monitors are being discovered. Command timeouts can extend the total recovery time.

    If controls are still missing after those retries, open Control Center → Monitor and use Rescan DDC/CI monitors (the refresh icon) to start another discovery attempt and retry cycle. Changing brightness configuration also starts a new cycle. Outputs configured with backend = "none" or backend = "backlight", and outputs already served by kernel backlight in auto mode, are excluded from DDC recovery.

    Section titled “Related IPC”

    For brightness commands, targets, accepted value formats, and OSD behavior, see System Controls → Brightness.