ThinkPad PrivacyScreen handle /proc/acpi/ibm/lcdshadow does not toggle hardware

[Pellaeon Lin]

My laptop is equipped with PrivacyGuard, however the hardware feature does not work since one upgrade in Ubuntu 23.04. I just upgraded to 23.10 and this issue is still not fixed. It used to work when I was using 22.04.

I have tested writing to the procfs interface directly: `echo 0 > /proc/acpi/ibm/lcdshadow` This command have no effect, even though the status `cat /proc/acpi/ibm/lcdshadow` is changed.

I also tried rebooting into the UEFI setup, then pressing Ctrl+D (the PrivacyGuard hotkey). This works as expected. (Toggles the PrivacyGuard.)

Currently, under 23.10, the PrivacyGuard seemed to be stuck on the "on" state.

Ubuntu release: 23.10
Kernel version: 6.5.0-13-generic

ProblemType: Bug
DistroRelease: Ubuntu 23.10
Package: linux-image-6.5.0-13-generic 6.5.0-13.13
ProcVersionSignature: Ubuntu 6.5.0-13.13-generic 6.5.3
Uname: Linux 6.5.0-13-generic x86_64
NonfreeKernelModules: zfs
ApportVersion: 2.27.0-0ubuntu5
Architecture: amd64
CasperMD5CheckResult: pass
CurrentDesktop: KDE
Date: Thu Nov 23 21:11:40 2023
HibernationDevice: RESUME=none
InstallationDate: Installed on 2021-12-17 (706 days ago)
InstallationMedia: Ubuntu 21.10 "Impish Indri" - Release amd64 (20211012)
MachineType: {report['dmi.sys.vendor']} {report['dmi.product.name']}
ProcFB: 0 amdgpudrmfb
ProcKernelCmdLine: BOOT_IMAGE=/BOOT/ubuntu_vt52bg@/vmlinuz-6.5.0-13-generic root=ZFS=rpool/ROOT/ubuntu_vt52bg ro quiet splash vt.handoff=1
PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No PulseAudio daemon running, or not running as session daemon.
RelatedPackageVersions:
 linux-restricted-modules-6.5.0-13-generic N/A
 linux-backports-modules-6.5.0-13-generic N/A
 linux-firmware 20230919.git3672ccab-0ubuntu2.2
SourcePackage: linux
UpgradeStatus: Upgraded to mantic on 2023-10-31 (23 days ago)
dmi.bios.date: 06/27/2022
dmi.bios.release: 1.21
dmi.bios.vendor: LENOVO
dmi.bios.version: R1NET51W (1.21)
dmi.board.asset.tag: Not Available
dmi.board.name: 20XHCTO1WW
dmi.board.vendor: LENOVO
dmi.board.version: SDK0R32862 WIN
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: None
dmi.ec.firmware.release: 1.21
dmi.modalias: dmi:bvnLENOVO:bvrR1NET51W(1.21):bd06/27/2022:br1.21:efr1.21:svnLENOVO:pn20XHCTO1WW:pvrThinkPadX13Gen2a:rvnLENOVO:rn20XHCTO1WW:rvrSDK0R32862WIN:cvnLENOVO:ct10:cvrNone:skuLENOVO_MT_20XH_BU_Think_FM_ThinkPadX13Gen2a:
dmi.product.family: ThinkPad X13 Gen 2a
dmi.product.name: 20XHCTO1WW
dmi.product.sku: LENOVO_MT_20XH_BU_Think_FM_ThinkPad X13 Gen 2a
dmi.product.version: ThinkPad X13 Gen 2a
dmi.sys.vendor: LENOVO