edido: init

#!/usr/bin/env bash

set -eEuo pipefail

test -z "${DEBUG:-}" || set -x

set -eEuo pipefail

FIRMWARE_PATH="${EDID_PATH:-"/run/current-system/firmware"}"

mapfile -t edid_paths <<<"${FIRMWARE_PATH//":"/$'\n'}"

err() {

  LOGGER="ERROR" log "$@"

  return 1

}

log() {

  # shellcheck disable=SC2059

  printf "[${LOGGER:-"INFO"}] $1\n" "${@:2}" >&2

}

find_path() {

  local filePath="$1"

  mapfile -t candidates < <(

    set -x

    find -L "${@:2}" -path "*/${filePath}"

  )

  if test "${#candidates[@]}" -eq 0; then

    log "'%s' path not found" "${filePath}"

    return 1

  fi

  log "'%s' path found at %s" "${filePath}" "${candidates[0]}"

  echo -n "${candidates[0]}"

}

wait_for_file() {

  local filePath="$1"

  until find_path "${filePath}" "${@:2}"; do

    backoff "${filePath}"

  done

}

backoff() {

  local what="$1" sleepFor

  backoff_start="${backoff_start:-"5"}"

  backoff_current="${backoff_current:-"${backoff_start}"}"

  backoff_jitter_multiplier="${backoff_jitter_multiplier:-"0.3"}"

  backoff_multiplier="${backoff_multiplier:-1.5}"

  sleepFor="$(bc <<<"${backoff_current} + ${RANDOM} % (${backoff_current} * ${backoff_jitter_multiplier})")"

  log "still waiting for '%s', retry in %s sec..." "${what}" "${sleepFor}"

  sleep "${sleepFor}"

  backoff_current="$(bc <<<"scale=2; ${backoff_current} * ${backoff_multiplier}")"

}

force_mode() {

  local connPath="$1" newMode="$2" currentMode

  currentMode="$(cat "$connPath/force")"

  if test "${currentMode}" == "${newMode}"; then

    log "video mode is already '%s'" "${currentMode}"

    return

  fi

  log "changing video mode from '%s' to '%s'" "${currentMode}" "${newMode}"

  echo "${newMode}" >"$connPath/force"

  CHANGED=1

}

force_edid() {

  local connPath="$1" edidPath="$2"

}

apply_mode() {

  local connPath="$1" mode="$2"

  test -n "$mode" || return

  log "setting up fb mode..."

  # see https://github.com/torvalds/linux/blob/8cd26fd90c1ad7acdcfb9f69ca99d13aa7b24561/drivers/gpu/drm/drm_sysfs.c#L202-L207

  # see https://docs.kernel.org/fb/modedb.html

  case "${mode}" in

  *d) force_mode "$connPath" off ;;

  *e) force_mode "$connPath" on ;;

  *D) force_mode "$connPath" on-digital ;;

  esac

}

apply_edid() {

  local connPath="$1" edidFilename="$2" edidPath

  test -n "${edidFilename}" || return

  log "loading EDID override..."

  edidPath="$(find_path "${edidFilename}" "${edid_paths[@]/%/"/"}" -maxdepth 2)"

  force_edid "${connPath}" "$edidPath"

  cat "$edidPath" >"${connPath}/edid_override"

  if cmp "${connPath}/edid_override" "${edidPath}" &>/dev/null; then

    log "EDID is already up to date with '%s'" "${edidPath}"

  else

    log "applying EDID override from ${edidPath}"

    cat "$edidPath" >"${connPath}/edid_override"

    CHANGED=1

  fi

}

load() {

  local conn="$1" edidFilename="$2" mode="$3"

  export LOGGER="$conn:${edidFilename}:$mode"

  CHANGED="${CHANGED:-0}"

  log "starting configuration"

  local connPath

  connPath="$(wait_for_file "$conn" /sys/kernel/debug/dri/ -maxdepth 2 -type d)"

  apply_edid "${connPath}" "${edidFilename}"

  apply_mode "${connPath}" "$mode"

  if test "${CHANGED}" != 0; then

    log "changes detected, triggering hotplug"

    echo 1 >"${connPath}/trigger_hotplug"

  else

    log "no changes detected, skipping hotplug trigger"

  fi

}

main() {

  if [[ $EUID -ne 0 ]]; then

    err "must be run as root"

  fi

  if test "$#" == 0; then

    log "loading kernel parameters from /proc/cmdline"

    # replace script arguments with kernel parameters

    mapfile -t args < <(xargs -n1 </proc/cmdline)

  else

    log "loading kernel parameters compatible arguments from commandline"

    args=("$@")

  fi

  local -A edids modes connectors

  local -a entries

  local key value

  for arg in "${args[@]}"; do

    key="${arg%%=*}"

    value=""

    test "${key}" == "${arg}" || value="${arg#*=}"

    case "${key}" in

    video)

      # one argument per connector:

      #   video=DP-4:e video=DP-1:e

      connector="${value%:*}"

      mode="${value#*:}"

      connectors["${connector}"]=""

      modes["$connector"]="$mode"

      ;;

    drm.edid_firmware)

      # single argument for all connectors:

      #   drm.edid_firmware=DP-4:edid/one.bin,DP-1:edid/two.bin

      mapfile -t entries <<<"${value//","/$'\n'}"

      for entry in "${entries[@]}"; do

        connector="${entry%:*}"

        edidFilename="${entry#*:}"

        connectors["${connector}"]=""

        edids["${connector}"]="${edidFilename}"

      done

      ;;

    esac

  done

  for connector in "${!connectors[@]}"; do

    # spawn in a subshell to easily adjust and runtime modify global variables

    (load "${connector}" "${edids["${connector}"]:-""}" "${modes["${connector}"]:-""}") &

  done

  wait

}

main "$@"

{ lib

, writeShellApplication

, bc

, diffutils

, findutils

, coreutils

, firmwarePaths ? [

    "/run/current-system/firmware"

  ]

}:

writeShellApplication {

  name = "edido";

  meta.description = "A tool to apply display configuration from `boot.kernelParams`.";

  runtimeInputs = [ diffutils findutils coreutils bc ];

  text = ''

    FIRMWARE_PATH="''${FIRMWARE_PATH:-"${builtins.concatStringsSep ":" firmwarePaths}"}"

    ${builtins.readFile ./edido.sh}

  '';

}