Use custom config.txt

config/config.exs

@@ -104,6 +104,9 @@ config :nerves_hub_link,
   host: "https://your-nerves-hub-server.com",
   configurator: NervesHubLink.Configurator.SharedSecret
 
+config :nerves, :firmware,
+  fwup_conf: "config/fwup.conf"
+
 if Mix.target() == :host do
   import_config "host.exs"
 else

config/config.txt

@@ -0,0 +1,72 @@
+# Default Nerves RPi 4 config.txt
+#
+# It's possible to override this file by using a custom fwup.conf
+# configuration to pull in a replacement.
+#
+# Useful links:
+# http://rpf.io/configtxt
+# https://www.raspberrypi.org/documentation/configuration/device-tree.md
+# https://github.com/raspberrypi/documentation/blob/master/configuration/device-tree.md
+# https://github.com/raspberrypi/firmware/blob/master/boot/overlays/README
+
+# Enable 64-bit support
+arm_64bit=1
+
+# We always use the same names. The variant is selected in fwup.conf.
+start_file=start4.elf
+fixup_file=fixup4.dat
+
+# Disable the boot rainbow
+disable_splash=1
+
+# This, along with the Raspberry Pi "x" firmware is needed for the camera
+# to work. The Raspberry Pi "x" firmware is selected via the Buildroot
+# configuration. See Target packages->Hardware handling->Firmware.
+gpu_mem=192
+
+# Enable I2C and SPI
+dtparam=i2c_arm=on
+dtparam=spi=on
+dtparam=i2c_arm_baudrate=400000
+
+# Enable audio (loads snd_bcm3825)
+dtparam=audio=on
+
+# Automatically load overlays for detected cameras
+camera_auto_detect=1
+
+# Automatically load overlays for detected DSI displays
+display_auto_detect=1
+
+# Enable DRM VC4 V3D driver
+dtoverlay=vc4-kms-v3d
+max_framebuffers=2
+
+# Don't have the firmware create an initial video= setting in cmdline.txt.
+# Use the kernel's default instead.
+disable_fw_kms_setup=1
+
+# Disable compensation for displays with overscan
+disable_overscan=1
+
+# Comment this in or modify to enable OneWire
+# NOTE: check that the overlay that you specify is in the boot partition or
+#       this won't work.
+#dtoverlay=w1-gpio-pullup,gpiopin=4
+
+# Support USB gadget mode on the USB-C port
+dtoverlay=dwc2
+
+# The ramoops overlay works with the pstore driver to preserve crash
+# information across reboots in DRAM
+dtoverlay=ramoops
+
+# Enable the UART (/dev/ttyS0)
+enable_uart=1
+
+[cm4]
+# Raspberry Pi CM4-only settings
+
+# For the CM4 I/O board, USB is disabled by default. This enables it.
+dtoverlay=dwc2,dr_mode=host
+