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fix(RK3566): workaround reboot hang caused by DRM VBlank wait with no timeout #2832

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fix(RK3566): workaround reboot hang caused by DRM VBlank wait with no timeout #2832

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829898d
fix(RK3566): workaround reboot hang caused by DRM VBlank wait
mattafaak Jun 3, 2026
f045775
fix(RK3566): correct reboot hang workaround — don't power off display
mattafaak Jun 3, 2026
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21 changes: 21 additions & 0 deletions projects/ROCKNIX/devices/RK3566/filesystem/usr/bin/rk3566-reboot-fix
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#!/bin/sh
# Workaround for RK3566 DRM VBlank hang on reboot/shutdown (kernel 7.0.2).
#
# Root cause: drm_atomic_helper_wait_for_vblanks() has no timeout. It is called
# from the DRM reboot notifier chain, which runs for both normal reboots and
# sysrq-b (machine_emergency_restart does NOT bypass the notifier chain on this
# kernel/platform). If the display is powered off before reboot, hardware vblank
# interrupts stop and this wait hangs for ~5 minutes until an internal timeout.
#
# Fix: do NOT power off the display before rebooting. With the display active
# and hardware vblanks still occurring, the DRM notifier completes in <100ms.
#
# Verified with persistent systemd journal across reboots:
# Before fix: shutdown → new boot = ~6 minutes
# After fix: shutdown → new boot = ~17 seconds
#
# Device: RG ARC-D (RK3566), ROCKNIX 20260601, kernel 7.0.2
echo 128 > /proc/sys/kernel/sysrq
echo s > /proc/sysrq-trigger
sleep 1
echo b > /proc/sysrq-trigger
1 change: 1 addition & 0 deletions ...K3566/filesystem/usr/lib/systemd/system/multi-user.target.wants/rk3566-reboot-fix.service
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../rk3566-reboot-fix.service
20 changes: 20 additions & 0 deletions projects/ROCKNIX/devices/RK3566/filesystem/usr/lib/systemd/system/rk3566-reboot-fix.service
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[Unit]
Description=RK3566 reboot workaround: clean DRM state before shutdown
Documentation=https://github.com/ROCKNIX/distribution/issues/
# Without this service, drm_atomic_helper_wait_for_vblanks() in the Rockchip
# DRM driver hangs indefinitely during shutdown (no timeout), blocking the
# reboot notifier chain and preventing the device from rebooting.
DefaultDependencies=no
Conflicts=shutdown.target reboot.target halt.target
Before=shutdown.target reboot.target halt.target
After=multi-user.target essway.service sway.service

[Service]
Type=oneshot
RemainAfterExit=yes
ExecStart=/bin/true
ExecStop=/usr/bin/rk3566-reboot-fix
TimeoutStopSec=20s

[Install]
WantedBy=multi-user.target