ec/lenovo/h8/acpi: Fix regression (MS Windows crash on boot)

Fix a regression introduced by #21227 0709dc04
(ec/lenovo/h8/acpi/thermal: Add ACPI fan control).

The commit caused Windows to crash as EC reads aren't allowed in the fan
device or it's powerresource's methods. Implement the same approach as all
other platforms using a GNVS variable named FLVL instead of reading from EC.

In addition to EC reads writing to FIELD elements, in another ACPI scope,
seems to be broken. Introduce a new method to set the fan disengage mode.

Tested on Windows 7 and Lenovo T500.

Change-Id: Ia99f8814ac14194578dcd1aa50a63e3f35c042dd
Signed-off-by: Patrick Rudolph <>
Tested-by: build bot (Jenkins) <>
Reviewed-by: Alexander Couzens <>
2 files changed