ergosteurandClaude Opus 5.5
9c3b8e48ee
An apt upgrade switched the display manager from SDDM to plasmalogin, whose kwin_wayland greeter never runs the SDDM Xsetup hook. Add a plasma-login.service user drop-in that cycles DPMS off/on with kscreen-doctor on 7.x kernels, forcing the full modeset that un-sticks i915 pipe A (a plain resolution change is absorbed by the eDP panel fitter and doesn't help). Verified across a cold reboot. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
120 lines
4.2 KiB
Bash
Executable File
120 lines
4.2 KiB
Bash
Executable File
#!/bin/sh
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# setup-i915-kernel7-fix.sh
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#
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# Run on a fresh hp-chell (HP Chromebook 13 "chell", coreboot/MrChromebox
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# firmware, KDE neon) install to apply two things:
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#
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# 1. The kernel 7.x cold-boot black-screen workaround, which forces a
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# second modeset on eDP-1 to un-stick i915's pipe A on 7.x kernels:
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# a /usr/share/sddm/scripts/Xsetup hook (SDDM) and a
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# plasma-login.service drop-in doing a DPMS cycle (Plasma Login).
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# See project CLAUDE.md for the full diagnosis writeup.
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# 2. GRUB_TIMEOUT=5 / GRUB_TIMEOUT_STYLE=menu, so the boot menu is
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# visible for 5 seconds (useful for picking a fallback kernel like
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# 6.17.0-42-generic if a future 7.x point release regresses again).
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#
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# Safe to re-run; idempotent.
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set -eu
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if [ "$(id -u)" -ne 0 ]; then
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echo "must run as root (sudo $0)" >&2
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exit 1
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fi
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echo "==> installing SDDM Xsetup i915 kernel-7.x workaround"
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cat > /usr/share/sddm/scripts/Xsetup << 'EOF'
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#!/bin/sh
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# Xsetup - run as root before the login dialog appears
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if [ -e /sbin/prime-offload ]; then
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echo running NVIDIA Prime setup /sbin/prime-offload
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/sbin/prime-offload
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fi
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# Workaround: on kernel 7.x, the first i915 modeset at cold boot (Xorg's
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# auto-modeset to the panel's native 3200x1800) leaves pipe A in a bad
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# state (persistent CPU pipe A FIFO underrun -> blank panel, backlight
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# still on, even though DRM/plane state reports healthy). Forcing a
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# second modeset unsticks it. Rather than cycle back to native, just
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# land on 1600x900 (exact half of 3200x1800, clean 2x integer scaling)
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# and stay there -- it's only the login screen; the logged-in session
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# renews the modeset itself and comes up at full native resolution.
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# Not needed on 6.17.x kernels. See project CLAUDE.md for the full
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# writeup.
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case "$(uname -r)" in
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7.*)
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xrandr --output eDP-1 --mode 1600x900 >/tmp/xsetup-modeset.log 2>&1
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echo "set eDP-1 to 1600x900 (i915 kernel 7.x cold-boot workaround)"
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;;
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esac
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EOF
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chmod 755 /usr/share/sddm/scripts/Xsetup
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# Plasma Login (plasmalogin, replaced SDDM on neon in 2026-09) runs its
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# greeter under kwin_wayland, so the SDDM Xsetup hook above never fires.
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# Equivalent fix there: a DPMS off/on cycle via kscreen-doctor, run from
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# the greeter's own systemd user manager right after KWin comes up. A
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# plain resolution change is NOT enough under KWin -- the eDP panel
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# fitter absorbs it as a fastset without a real pipe modeset; DPMS off
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# fully disables the CRTC so the "on" is a genuine full modeset.
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echo "==> installing plasmalogin greeter i915 kernel-7.x workaround"
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install -d /usr/local/libexec
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cat > /usr/local/libexec/hp-chell-i915-dpms-cycle << 'EOF'
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#!/bin/sh
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# Run as the plasmalogin greeter user (from plasma-login.service's
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# ExecStartPre). Forces a full modeset on kernel 7.x to un-stick i915
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# pipe A after the cold-boot first modeset. See hp-chell CLAUDE.md.
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case "$(uname -r)" in
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7.*) ;;
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*) exit 0 ;;
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esac
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[ "$(id -un)" = plasmalogin ] || exit 0
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export WAYLAND_DISPLAY="${WAYLAND_DISPLAY:-wayland-0}"
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export QT_QPA_PLATFORM=wayland
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# wait (up to ~20s) for KWin's output management to answer
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i=0
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until kscreen-doctor -o >/dev/null 2>&1; do
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i=$((i + 1))
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[ "$i" -ge 40 ] && { echo "kscreen-doctor never came up" >&2; exit 0; }
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sleep 0.5
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done
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kscreen-doctor --dpms off >/dev/null 2>&1
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sleep 1
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kscreen-doctor --dpms on >/dev/null 2>&1
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echo "cycled DPMS off/on (i915 kernel 7.x cold-boot workaround)"
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EOF
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chmod 755 /usr/local/libexec/hp-chell-i915-dpms-cycle
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install -d /etc/systemd/user/plasma-login.service.d
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cat > /etc/systemd/user/plasma-login.service.d/10-i915-kernel7-dpms-cycle.conf << 'EOF'
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[Service]
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ExecStartPre=-/usr/local/libexec/hp-chell-i915-dpms-cycle
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EOF
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echo "==> setting GRUB_TIMEOUT=5 / GRUB_TIMEOUT_STYLE=menu"
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grub_conf=/etc/default/grub
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set_grub_key() {
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key=$1
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value=$2
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if grep -q "^${key}=" "$grub_conf"; then
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sed -i "s|^${key}=.*|${key}=${value}|" "$grub_conf"
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elif grep -q "^#${key}=" "$grub_conf"; then
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sed -i "s|^#${key}=.*|${key}=${value}|" "$grub_conf"
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else
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echo "${key}=${value}" >> "$grub_conf"
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fi
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}
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set_grub_key GRUB_TIMEOUT 5
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set_grub_key GRUB_TIMEOUT_STYLE menu
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echo "==> running update-grub"
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update-grub
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echo "==> done"
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