busybox: add script to modify edid override with RPi bootloader

The script supports two operations:

"set" enables initramfs cpio in config.txt and adds edid and video
override kernel options for the specified connectors to cmdline.txt

"delete" removes edid.cpio initramfs loading in config.txt and
removes all edid override and video options from cmdline.txt

Signed-off-by: Matthias Reichl <hias@horus.com>

packages/sysutils/busybox/package.mk

@@ -128,6 +128,9 @@ makeinstall_target() {
       cp ${PKG_DIR}/scripts/dump-active-edids-drm ${INSTALL}/usr/bin/dump-active-edids
     fi
     cp ${PKG_DIR}/scripts/create-edid-cpio ${INSTALL}/usr/bin/
+    if [ "${PROJECT}" = "RPi" ]; then
+      cp ${PKG_DIR}/scripts/update-bootloader-edid-rpi ${INSTALL}/usr/bin/update-bootloader-edid
+    fi
     cp ${PKG_DIR}/scripts/createlog ${INSTALL}/usr/bin/
     cp ${PKG_DIR}/scripts/dthelper ${INSTALL}/usr/bin
       ln -sf dthelper ${INSTALL}/usr/bin/dtfile

packages/sysutils/busybox/scripts/update-bootloader-edid-rpi

@@ -0,0 +1,95 @@
+#!/bin/sh
+
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (C) 2021-present Team LibreELEC (https://libreelec.tv)
+
+EDID_DIR="/storage/.config/firmware/edid"
+EDID_CPIO="/flash/edid.cpio"
+CONFIG_TXT="/flash/config.txt"
+CMDLINE_TXT="/flash/cmdline.txt"
+
+usage() {
+  echo "$0 set CONNECTOR... | delete | help"
+}
+
+check_args() {
+  if [ $# -eq 0 ]; then
+    echo "error: no connector(s) specified!"
+    exit 1
+  fi
+  if [ ! -f "${EDID_CPIO}" ]; then
+    echo "error: ${EDID_CPIO} not present"
+    exit 1
+  fi
+  for conn in "$@"; do
+    if [ ! -f "${EDID_DIR}/edid-${conn}.bin" ]; then
+      echo "error: ${EDID_DIR}/edid-${conn}.bin not present"
+      exit 1
+    fi
+  done
+}
+
+cleanup_config_txt() {
+  sed -i "/^initramfs edid\.cpio/d" ${CONFIG_TXT}
+}
+
+get_cleaned_cmdline_txt() {
+  sed \
+    -e 's| drm\.edid_firmware=[^ ]*||g' \
+    -e 's| video=[^ ]*||g' \
+    ${CMDLINE_TXT}
+}
+
+add_initramfs() {
+  # make sure config.txt ends with a newline
+  if [ "$(tail -c 1 ${CONFIG_TXT} | tr -c -d '\n' | tr '\n' 'X')" != "X" ]; then
+    echo "" >> ${CONFIG_TXT}
+  fi
+  echo "initramfs edid.cpio" >> ${CONFIG_TXT}
+}
+
+add_cmdline() {
+  CMDLINE=$(get_cleaned_cmdline_txt)
+  FIRMWARE="" 
+  VIDEO=""
+  for conn in "$@"; do
+    VIDEO="${VIDEO} video=${conn}:D"
+    [ -n "${FIRMWARE}" ] && FIRMWARE="${FIRMWARE},"
+    FIRMWARE="${FIRMWARE}${conn}:edid/edid-${conn}.bin"
+  done
+  echo "${CMDLINE} drm.edid_firmware=${FIRMWARE}${VIDEO}" > ${CMDLINE_TXT}
+}
+
+set_edids() {
+  check_args "$@"
+  mount -o remount,rw /flash
+  cleanup_config_txt
+  add_initramfs
+  add_cmdline "$@"
+  mount -o remount,ro /flash
+}
+
+delete_edids() {
+  mount -o remount,rw /flash
+  cleanup_config_txt
+  CMDLINE=$(get_cleaned_cmdline_txt)
+  echo "${CMDLINE}" > ${CMDLINE_TXT}
+  mount -o remount,ro /flash
+}
+
+case $1 in
+  set)
+    shift
+    set_edids "$@"
+    ;;
+  delete)
+    delete_edids
+    ;;
+  help)
+    usage
+    ;;
+  *)
+    usage
+    exit 1
+    ;;
+esac