[BUG] Lenovo ThinkPad X12 Detachable Gen 2 (21LK001LGE): INT3472 discrete missing board-data / broken _DEP for OV8856 rear camera

[haju-ecos]

acpidump.bin.gz

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[BUG] Lenovo ThinkPad X12 Detachable Gen 2 (21LK001LGE): INT3472 discrete missing board-data / broken _DEP for OV8856 rear camera

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Description:

Hello,

I am trying to get the camera system working on the new Lenovo ThinkPad X12 Detachable Gen 2 under Linux (Kernel 7.1.2/7.6.2).

While the front camera (Chicony USB UVC) works out of the box, the rear camera (OmniVision OV8856, ACPI ID: OVTI8856:00) fails to probe with an I2C read timeout (error -5).

Hardware & Environment:

• System: Lenovo ThinkPad X12 Detachable Gen 2 [1.1.5]
• DMI board_name / product_name: 21LK001LGE
• Platform: Intel Meteor Lake (Core Ultra)
• Sensor: OmniVision OV8856 (OVTI8856:00)
• Kernel: Custom Gentoo build (v7.1.2 / v7.6.2)

Symptoms & Logs:

Upon boot, the ov8856 driver attempts to probe but times out on i2c_designware.2 [2.1.8]:

[   12.129093] i2c_designware i2c_designware.2: controller timed out
[   12.129110] ov8856 i2c-OVTI8856:00: failed to find sensor: -5
[   12.129125] ov8856 i2c-OVTI8856:00: probe with driver ov8856 failed with error -5

During earlier debugging, intel_skl_int3472_discrete loaded but threw the following warning [1.2.8, 2.4.4]:

[ 3453.889943] int3472-discrete INT3472:01: INT3472 seems to have no dependents.

Because of this missing ACPI dependency (_DEP / _PLD), the driver failed to map any power regulators or clocks to the sensor [2.3.2, 2.4.4].

Debugging & Root Cause Analysis:

1. Bypassing the ACPI dependency bug:
   We patched drivers/platform/x86/intel/int3472/common.c in skl_int3472_get_sensor_adev_and_name to include a manual fallback for "OVTI8856" when acpi_dev_get_next_consumer_dev returns NULL.
   With this patch, the driver successfully binds to INT3472:01 without throwing any warnings.

2. Missing Board-Data:
   Even though the driver successfully binds with the fallback patch, the ov8856 sensor still times out with -5. This is because there is no matching DMI board-data entry for 21LK001LGE in drivers/platform/x86/intel/int3472/discrete.c [3.4.4].
   The driver does not know which physical GPIO pins to toggle (reset/powerdown) or which clock to register, leaving the camera unpowered [3.1.1, 3.4.4].

Attached Files:

I have attached the acpidump from this system (acpidump.bin).

Could you please help analyze the ACPI tables to extract the correct GPIO/clock configuration and add the corresponding DMI board-data quirk for the ThinkPad X12 Detachable Gen 2 (21LK001LGE) to discrete.c? [3.4.4]

Thank you very much for your help!