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Parameterize and fix race condition for i2samp #404

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Merged
makermelissa merged 2 commits into from
Jun 30, 2026
Merged

Parameterize and fix race condition for i2samp #404

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5f1df77
Parameterize and fix race condition for i2samp
makermelissa Jun 30, 2026
959091e
Address review suggestions
makermelissa Jun 30, 2026
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52 changes: 43 additions & 9 deletions i2samp.py
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,8 @@
PRODUCT_NAME = "I2S Amplifier"
OVERLAY = "googlevoicehat-soundcard"
CARD_NAME_FALLBACK = "sndrpigooglevoi"
I2SAMP_INIT_SERVICE = "adafruit-i2samp-init.service"
APLAY_SERVICE = "aplay.service"

def get_card_name(overlay):
"""Load overlay at runtime and discover the ALSA card id from aplay -l."""
Expand Down Expand Up @@ -48,10 +50,13 @@ def uninstall():
if config is None:
shell.bail("No Device Tree Detected, not supported")

print("\nStopping and removing aplay systemd unit...")
shell.run_command("sudo systemctl stop aplay", suppress_message=True)
shell.run_command("sudo systemctl disable aplay", suppress_message=True)
shell.remove("/etc/systemd/system/aplay.service")
print("\nStopping and removing systemd units...")
shell.run_command(f"sudo systemctl stop {APLAY_SERVICE}", suppress_message=True)
shell.run_command(f"sudo systemctl disable {APLAY_SERVICE}", suppress_message=True)
shell.run_command(f"sudo systemctl stop {I2SAMP_INIT_SERVICE}", suppress_message=True)
shell.run_command(f"sudo systemctl disable {I2SAMP_INIT_SERVICE}", suppress_message=True)
shell.remove(f"/etc/systemd/system/{APLAY_SERVICE}")
shell.remove(f"/etc/systemd/system/{I2SAMP_INIT_SERVICE}")
shell.run_command("sudo systemctl daemon-reload")

print(f"Removing Device Tree overlay from {config}")
Expand Down Expand Up @@ -192,12 +197,40 @@ def install():
shell.run_command(f"amixer -D 'plug:softvol' sset PCM 100% > /dev/null 2>&1")
shell.run_command("sudo alsactl store")

print("Installing I2S amplifier initialization systemd unit")
shell.write_text_file(f"/etc/systemd/system/{I2SAMP_INIT_SERVICE}", f"""
[Unit]
Description=Initialize Adafruit I2S amplifier softvol control.
After=local-fs.target sound.target
Wants=sound.target
Before={APLAY_SERVICE}
StartLimitBurst=5
StartLimitIntervalSec=60

[Service]
Type=oneshot
RemainAfterExit=yes
Restart=on-failure
RestartSec=5s

ExecStartPre=/bin/sh -c 'i=0; while [ "$i" -lt 30 ]; do \\
/usr/bin/aplay -l | /bin/grep -qi "{card_name}" && exit 0; \\
i=$((i+1)); /bin/sleep 1; \\
done; exit 1'
ExecStart=/bin/sh -c '/usr/bin/amixer -c "{card_name}" controls | \\
/bin/grep -qi "name=.*PCM" || \\
/usr/bin/amixer -D plug:softvol sset PCM 100%'
ExecStart=-/usr/sbin/alsactl restore

[Install]
WantedBy=multi-user.target""", append=False)

print("Installing aplay systemd unit")
shell.write_text_file("/etc/systemd/system/aplay.service", """
shell.write_text_file(f"/etc/systemd/system/{APLAY_SERVICE}", f"""
[Unit]
Description=Invoke aplay from /dev/zero at system start.
After=sound.target
Wants=sound.target
Requires={I2SAMP_INIT_SERVICE}
After={I2SAMP_INIT_SERVICE}
StartLimitBurst=5
StartLimitIntervalSec=60

Expand All @@ -211,12 +244,13 @@ def install():
WantedBy=multi-user.target""", append=False)

shell.run_command("sudo systemctl daemon-reload")
shell.run_command("sudo systemctl disable aplay")
shell.run_command(f"sudo systemctl enable {I2SAMP_INIT_SERVICE}")
shell.run_command(f"sudo systemctl disable {APLAY_SERVICE}")
print("\nYou can optionally activate '/dev/zero' playback in\n"
"the background at boot. This will remove all\n"
"popping/clicking but does use some processor time.\n\n")
if shell.prompt("Activate '/dev/zero' playback in background? [RECOMMENDED]\n", default="y"):
shell.run_command("sudo systemctl enable aplay")
shell.run_command(f"sudo systemctl enable {APLAY_SERVICE}")
reboot = True

if driver_loaded("max98357a"):
Expand Down