Dear Maintainer,

USB-C DisplayPort output does not work on my Lenovo Chromebook
(board name TANIKS) with the stock Debian amd64 kernel.

The system uses MrChromebox UEFI firmware and Debian 14. The internal
display works normally, but an external monitor connected through a
USB-C DisplayPort Alt Mode adapter is not detected.

The stock Debian 7.1.8+deb14.1-amd64 kernel configuration contains:

    # CONFIG_TYPEC_MUX_INTEL_PMC is not set
    CONFIG_INTEL_SCU_IPC=y
    # CONFIG_INTEL_SCU_PLATFORM is not set

The machine exposes the following relevant ACPI devices:

    INTC1026:00
    INTC105C:00

With the stock kernel, /sys/class/typec is empty and the deferred-device
list contains:

    INTC105C:00
    GOOG0014:00    cros-ec-typec: Failed to register port 0

The DRM connectors for the external outputs also remain disconnected:

    card0-DP-1: disconnected
    card0-DP-2: disconnected

I rebuilt the exact Debian 7.1.8 source using the stock Debian kernel
configuration and performed the following tests.

Test 1:

    CONFIG_TYPEC_MUX_INTEL_PMC=m
    # CONFIG_INTEL_SCU_PLATFORM is not set

Result: intel_pmc_mux was present and loaded, but INTC105C remained
deferred, cros_ec_typec could not register port 0, and USB-C DisplayPort
still did not work.

Test 2:

    CONFIG_TYPEC_MUX_INTEL_PMC=m
    CONFIG_INTEL_SCU_PLATFORM=m

Kconfig also selected:

    CONFIG_INTEL_SCU=y

CONFIG_INTEL_SCU_IPC=y was already enabled in the Debian configuration.

Result: after booting this kernel, the USB-C Type-C stack initializes
correctly and the external DisplayPort monitor works.

No kernel source changes were required. The only required changes were
enabling the existing upstream kernel configuration options.

This appears to be a Debian amd64 kernel configuration issue. Please
consider enabling:

    CONFIG_TYPEC_MUX_INTEL_PMC=m
    CONFIG_INTEL_SCU_PLATFORM=m

in the default Debian amd64 kernel configuration.

The controlled results were:

    stock Debian configuration:
        USB-C DisplayPort broken

    + CONFIG_TYPEC_MUX_INTEL_PMC=m:
        still broken

    + CONFIG_INTEL_SCU_PLATFORM=m:
        USB-C DisplayPort works

Expected result:
USB-C DisplayPort Alt Mode should work with the stock Debian kernel on
TANIKS without requiring a custom kernel.