https://bugzilla.kernel.org/show_bug.cgi?id=221859
Bug ID: 221859
Summary: Lenovo LOQ 15ARP9: ACPI _BCM evaluation failed,
backlight control broken
Product: ACPI
Version: 2.5
Hardware: AMD
OS: Linux
Status: NEW
Severity: normal
Priority: P3
Component: ACPICA-Core
Assignee: [email protected]
Reporter: [email protected]
Regression: No
Created attachment 310606
--> https://bugzilla.kernel.org/attachment.cgi?id=310606&action=edit
ACPI firmware error on Lenovo LOQ causes a nouveau driver initialization
failure (error -22) during backlight setup, completely breaking display
brightness control.
Hello,
I am reporting an issue with backlight control on my Lenovo LOQ 15ARP9 laptop
(Ryzen 5 7235HS, discrete NVIDIA GPU).
When using the open-source Nouveau driver, the brightness slider and hotkeys do
not work. The kernel log shows:
ACPI: \_SB_.PCI0.GPP0.PEGP.LCD0: _BCM evaluation failed
Troubleshooting steps performed:
Tested with acpi_backlight=vendor (ideapad module): the kernel created a
backlight node, but writing values (0-11) to brightness resulted in no visual
reaction.
Tested with acpi_backlight=native nouveau.debug=info: the backlight
directory is empty, and the UI slider disappears.
The proprietary NVIDIA driver works correctly. Karol Herbst (Nouveau
maintainer) suggested this is an ACPI subsystem issue rather than a driver bug.
I am attaching the full dmesg log with debug info. Please advise on how to fix
this ACPI routing issue.
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