Emerge.Config.DRM (Emerge v0.5.1)

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A display connected directly to Linux DRM/KMS, without a window manager. Set this record as Emerge.Config.output.

%Emerge.Config{
  output: %Emerge.Config.DRM{card: "/dev/dri/card0", connector: "DSI-1"},
  renderer: %Emerge.Config.Renderer{api: :opengl}
}

Fields

  • card — absolute path to the display's KMS device; defaults to "/dev/dri/card0". A stable /dev/dri/by-path/...-card path is also accepted.
  • connector — connector name, such as "DSI-1" or "DP-1". The default nil selects an available output automatically.
  • mode — an advertised mode ID or a mode map returned by EmergeSkia.drm_outputs/1. Defaults to nil for automatic mode selection. An explicit mode also requires an explicit connector. Invalid selections return an error rather than silently choosing another display or mode.
  • preferred_size — optional {width, height} hint for automatic mode selection. Defaults to nil. The selected mode determines the actual display size.
  • display — :on (default) or :off. Off blanks the display and ignores its UI input; it does not suspend your application or the operating system.
  • backlight — Emerge.Config.Backlight, defaulting to automatic association. Use it to select a panel backlight and request brightness.
  • hotplug_interval_ms — connector hotplug polling interval in milliseconds; defaults to 750. Set it to nil to disable polling for built-in panels.

Discover connector names and modes with EmergeSkia.drm_outputs(drm_card: path).

Changing settings

display and backlight brightness can change through config with an explicit OpenGL, Vulkan or raster renderer. Raster supports CPU presentation (including its :auto default) and explicit raster_present: :gpu_upload, which requires the OpenGL DRM presenter build. Automatic API selection does not support these controls. Off destroys the internal presenter; on recreates it and enables a managed backlight after its first application presentation. GPU resources are not restored.

Changing the card, connector, mode, size hint, backlight device or hotplug polling interval requires a new viewport. Applications using off/on need an independent wake source, such as a power-button reader; input from the blanked display cannot wake it.

Summary

Types

display()

Desired display state, not application or system power state.

normalized_t()

Canonical form after nested keyword records have been expanded.

t()

Types

display()

@type display() :: :on | :off

Desired display state, not application or system power state.

normalized_t()

@type normalized_t() :: %Emerge.Config.DRM{
  backlight: Emerge.Config.Backlight.normalized_t(),
  card: String.t(),
  connector: String.t() | nil,
  display: display(),
  hotplug_interval_ms: pos_integer() | nil,
  mode: String.t() | map() | nil,
  preferred_size: {pos_integer(), pos_integer()} | nil
}

Canonical form after nested keyword records have been expanded.

t()

@type t() :: %Emerge.Config.DRM{
  backlight: Emerge.Config.Backlight.t() | Emerge.Config.Backlight.options(),
  card: String.t(),
  connector: String.t() | nil,
  display: display(),
  hotplug_interval_ms: pos_integer() | nil,
  mode: String.t() | map() | nil,
  preferred_size: {pos_integer(), pos_integer()} | nil
}