Switch musicdolphin from a Pi 4 to a Pi 5

The SD card moves over as is, so:
- pi_standard_setup can install the Pi 5 kernel (linux-image-rpi-2712, an arm64
  package on the armhf userland), which a Pi 4 image lacks. Opt-in via
  pi_standard_setup_install_pi5_kernel.
- The Pi is powered through the HiFiBerry board's GPIO header, so it cannot negotiate
  a 5A supply and would cap USB at 600mA. pi_hifiberry_amp sets
  usb_max_current_enable=1 when hifiberry_powers_pi is true (default false).
- The DHT22 poller is off: Adafruit_DHT bit-bangs BCM283x registers, which the Pi 5
  no longer has (GPIO sits behind the RP1 chip).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

host_vars/musicdolphin.yml

@@ -9,7 +9,16 @@ main_user: root
 
 mediapi_has_hifiberry_amp: true
 mediapi_ir_control: irserver
-mediapi_has_dhtsensor: true
+# Off for the Pi 5: the legacy Adafruit_DHT library bit-bangs the BCM283x registers,
+# which the Pi 5 no longer has (GPIO sits behind the RP1 chip), so the poller cannot
+# work there. Needs a libgpiod-based replacement before this goes back to true.
+mediapi_has_dhtsensor: false
+
+# Raspberry Pi 5. The SD card came from a Pi 4, whose image has no Pi 5 kernel.
+pi_standard_setup_install_pi5_kernel: true
+# The Pi is fed 5V through the HiFiBerry board's GPIO header, not USB-C, so it cannot
+# negotiate a 5A supply and would cap USB current at 600mA.
+hifiberry_powers_pi: true
 
 # Display-only MusicMouse instance: no physical mouse attached, shown on the monitor
 # via pi_kiosk instead. See roles/pi_musicmouse/files/config-musicdolphin.yml.

roles/pi_hifiberry_amp/README.md

@@ -3,4 +3,7 @@
 Deactivates the Pi's onboard analog audio and activates a HiFiBerry
 amp/DAC overlay instead.
 
-**Key vars:** `hifiberry_overlay`
+**Key vars:** `hifiberry_overlay`, `hifiberry_powers_pi`
+
+`hifiberry_powers_pi` (default `false`) is for a Pi fed through the HiFiBerry board's
+GPIO header. On a Pi 5 that sets `usb_max_current_enable=1`, or USB is capped at 600mA.

roles/pi_hifiberry_amp/defaults/main.yml

@@ -0,0 +1,2 @@
+---
+hifiberry_powers_pi: false

roles/pi_hifiberry_amp/tasks/main.yml

@@ -11,3 +11,13 @@
     regexp: "^#?dtoverlay=hifiberry-amp"
     line: "dtoverlay={{ hifiberry_overlay }}"
   notify: Reboot
+- name: Lift the Pi 5's USB current cap when the HiFiBerry board powers it
+  # A Pi 5 fed over the GPIO header has no USB-C power negotiation, so it assumes a
+  # weak supply and limits USB ports to 600mA. Unknown to a Pi 4, which ignores it.
+  ansible.builtin.lineinfile:
+    path: /boot/firmware/config.txt
+    regexp: "^#?usb_max_current_enable="
+    line: "usb_max_current_enable=1"
+    insertafter: EOF
+  when: hifiberry_powers_pi
+  notify: Reboot

roles/pi_standard_setup/defaults/main.yml

@@ -9,3 +9,8 @@ pi_standard_setup_wifi_pass_url: "bauer_wifi" # has to be in keepass with url "w
 ansible_ssh_pass: "raspberry"
 ansible_become_password: "raspberry"
 ansible_become: true
+
+# Install the Pi 5 (BCM2712) kernel, kernel_2712.img (an arm64 package, hence the :arm64 on
+# the armhf userland). A card imaged on a Pi 4 does not have
+# it, and a Pi 5 will not boot without. Harmless on a Pi 4, which keeps its own kernel.
+pi_standard_setup_install_pi5_kernel: false

roles/pi_standard_setup/tasks/main.yml

@@ -115,6 +115,13 @@
       - telnet
     cache_valid_time: 7200
     state: present
+- name: Install the Pi 5 kernel
+  ansible.builtin.apt:
+    name: "linux-image-rpi-2712:arm64"
+    cache_valid_time: 7200
+    state: present
+  when: pi_standard_setup_install_pi5_kernel
+  notify: Reboot
 - name: Copy vim config
   ansible.builtin.copy:
     src: vimrc