No-reboot switching: source preflight

Recorded 2026-10-09T14:53:11.176690+00:00. Evidence class: local kernel source inspection only. No device tree was trial-booted and no physical plug/unplug transition was observed at this inspection. The accepted HDMI trial is prior evidence; the subsequent board preflight found the protected panel boot running (see panel-raw-hpd.json).

The existing LT9611 driver cannot be made a standalone monitor merely by adding its I2C node to the panel device tree:

• lt9611_parse_dt() requires a remote DSI node on input port 0 or 1, otherwise returning -ENODEV before revision detection.
• Its successful probe registers a DRM bridge and attaches a DSI device. Task 4.1 needs status monitoring while the panel keeps that host.
• HPD polling in lt9611_bridge_detect() reads register 0x825e and uses bits 2 or 0. Existing polling belongs to an attached HDMI connector; it does not establish a standalone poller during the panel boot.
• canaan_dsi_bind() resolves its downstream panel or bridge from the device-tree graph at bind time. canaan_dsi_attach() stores one device, and detach clears its panel, device and bridge pointers. This is not a runtime display-selection API.

Task 4.1 therefore needs a monitoring path that avoids attaching a second DSI consumer and leaves touch’s shared reset/IRQ ownership intact. Its physical proof remains open: the monitor must probe alongside the active panel, and actual cable changes must be checked. The HPD register’s behavior in that mode is still UNVERIFIED. Do not enable the shared HDMI IRQ merely because its electrical drive type remains unknown.

This does not establish that seamless switching is impossible. After a successful task-4.1 board proof, task 4.2 requires explicit kernel design for switching the DSI consumer and compositor-visible output. The optional reboot-based Settings prototype is not a substitute for that result.

Source artifacts at inspection:

• nix/patches/mainline/drm/lontium-lt9611-k230.c, SHA256 9efcaeffc8483725de6caccb0b5b7625df9a31db75ae76e0c5442f71ca54408c.
• nix/patches/mainline/drm/canaan_dsi.c, SHA256 6fec2adf9a154e09783c0892ff05fa3af3830094017f0444c2d6571bb3d38ac7.

Inspection command:

rg -n 'parse_dt|probe|detect|attach_dsi' nix/patches/mainline/drm/lontium-lt9611-k230.c
rg -n 'find_panel|bridge|attach|detach|bind' nix/patches/mainline/drm/canaan_dsi.c

Task 4.1 is not complete; no hardware outcome is inferred from this reading.