Backlight not working

Hey everyone
I have a Legion 5 (2022, Intel) with Intel Iris Xe iGPU. I have `/dev/backlight/intel_backlight0` and `backlight(8)` utility seems to work but the screen brightness doesn't change at all.
I did some research, I tried loading `acpi_video` module but it didn't export any sysctl variable and `x11/intel_backlight` port doesn't exist. Also I used `acpi_call` to invoke `\_SB.PC00.GFX0.DD1F._BCM` and `\_SB.PC00.GFX0.DD2F._BCM` but the behavior is the same as `backlight(8)` utility.
I'm running FreeBSD 15.0-RELEASE.

I guess it's worth noting that during boot, the screen brightness is higher when the device is in firmware and bootloader, and something dims the screen when FreeBSD kernel is loading ACPI. Also setting backlight to 0 turns off the display but any other value doesn't make any change.
I attached SSDT4 table too, it's where I found BQC and BCM ACPI methods.

Code:
% ls -l /dev/backlight
total 0
crw-rw----  1 root video 0x191 Dec  1 17:18 backlight0
lrwxr-xr-x  1 root wheel    23 Dec  1 17:18 intel_backlight0 -> ../backlight/backlight0

% backlight -i
Backlight name: intel_backlight
Backlight hardware type: Panel

% backlight
brightness: 100

% backlight 50
% backlight
brightness: 50

dmesg:
Code:
---<<BOOT>>---
Copyright (c) 1992-2025 The FreeBSD Project.
Copyright (c) 1979, 1980, 1983, 1986, 1988, 1989, 1991, 1992, 1993, 1994
    The Regents of the University of California. All rights reserved.
FreeBSD is a registered trademark of The FreeBSD Foundation.
FreeBSD 15.0-RELEASE releng/15.0-n280995-7aedc8de6446 GENERIC amd64
FreeBSD clang version 19.1.7 (https://github.com/llvm/llvm-project.git llvmorg-19.1.7-0-gcd708029e0b2)
VT(efifb): resolution 2560x1440
CPU: 12th Gen Intel(R) Core(TM) i7-12700H (2688.00-MHz K8-class CPU)
  Origin="GenuineIntel"  Id=0x906a3  Family=0x6  Model=0x9a  Stepping=3
  Features=0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE>
  Features2=0x7ffafbff<SSE3,PCLMULQDQ,DTES64,MON,DS_CPL,VMX,SMX,EST,TM2,SSSE3,SDBG,FMA,CX16,xTPR,PDCM,PCID,SSE4.1,SSE4.2,x2APIC,MOVBE,POPCNT,TSCDLT,AESNI,XSAVE,OSXSAVE,AVX,F16C,RDRAND>
  AMD Features=0x2c100800<SYSCALL,NX,Page1GB,RDTSCP,LM>
  AMD Features2=0x121<LAHF,ABM,Prefetch>
  Structured Extended Features=0x239c27eb<FSGSBASE,TSCADJ,BMI1,AVX2,FDPEXC,SMEP,BMI2,ERMS,INVPCID,NFPUSG,RDSEED,ADX,SMAP,CLFLUSHOPT,CLWB,PROCTRACE,SHA>
  Structured Extended Features2=0x98c007bc<UMIP,PKU,OSPKE,WAITPKG,GFNI,VAES,VPCLMULQDQ,RDPID,MOVDIRI,MOVDIR64B>
  Structured Extended Features3=0xfc18c410<FSRM,MD_CLEAR,IBT,IBPB,STIBP,L1DFL,ARCH_CAP,CORE_CAP,SSBD>
  XSAVE Features=0xf<XSAVEOPT,XSAVEC,XINUSE,XSAVES>
  IA32_ARCH_CAPS=0x1488fd6b<RDCL_NO,IBRS_ALL,SKIP_L1DFL_VME,MDS_NO,TAA_NO>
  VT-x: PAT,HLT,MTF,PAUSE,EPT,UG,VPID,VID,PostIntr
  TSC: P-state invariant, performance statistics
real memory  = 34359738368 (32768 MB)
avail memory = 33167273984 (31630 MB)
Event timer "LAPIC" quality 600
ACPI APIC Table: <LENOVO CB-01   >
FreeBSD/SMP: Multiprocessor System Detected: 20 CPUs
FreeBSD/SMP: Non-uniform topology
random: registering fast source Intel Secure Key Seed
random: fast provider: "Intel Secure Key Seed"
random: unblocking device.
ioapic0 <Version 2.0> irqs 0-119
Launching APs: 1 8 9 17 19 3 5 2 13 7 12 6 11 16 10 15 14 4 18
random: entropy device external interface
kbd1 at kbdmux0
efirtc0: <EFI Realtime Clock>
efirtc0: registered as a time-of-day clock, resolution 1.000000s
smbios0: <System Management BIOS> at iomem 0x40086000-0x4008601e
smbios0: Entry point: v2.1 (32-bit), Version: 3.3, BCD Revision: 3.3
aesni0: <AES-CBC,AES-CCM,AES-GCM,AES-ICM,AES-XTS,SHA1,SHA256>
acpi0: <LENOVO CB-01>
acpi0: Power Button (fixed)
hpet0: <High Precision Event Timer> iomem 0xfed00000-0xfed003ff on acpi0
Timecounter "HPET" frequency 19200000 Hz quality 950
Event timer "HPET" frequency 19200000 Hz quality 350
Event timer "HPET1" frequency 19200000 Hz quality 340
Event timer "HPET2" frequency 19200000 Hz quality 340
Event timer "HPET3" frequency 19200000 Hz quality 340
Event timer "HPET4" frequency 19200000 Hz quality 340
Event timer "HPET5" frequency 19200000 Hz quality 340
Event timer "HPET6" frequency 19200000 Hz quality 340
Event timer "HPET7" frequency 19200000 Hz quality 340
atrtc1: <AT realtime clock> on acpi0
atrtc1: Warning: Couldn't map I/O.
atrtc1: registered as a time-of-day clock, resolution 1.000000s
Event timer "RTC" frequency 32768 Hz quality 0
attimer0: <AT timer> port 0x40-0x43,0x50-0x53 irq 0 on acpi0
Timecounter "i8254" frequency 1193182 Hz quality 0
Event timer "i8254" frequency 1193182 Hz quality 100
Timecounter "ACPI-fast" frequency 3579545 Hz quality 900
acpi_timer0: <24-bit timer at 3.579545MHz> port 0x1808-0x180b on acpi0
acpi_ec0: <Embedded Controller: GPE 0x6e> port 0x62,0x66,0x270-0x27f on acpi0
pcib0: <ACPI Host-PCI bridge> port 0xcf8-0xcff on acpi0
pci0: <ACPI PCI bus> on pcib0
pcib1: <ACPI PCI-PCI bridge> at device 1.0 on pci0
vgapci0: <VGA-compatible display> port 0x6000-0x603f mem 0x6103000000-0x6103ffffff,0x4000000000-0x400fffffff at device 2.0 on pci0
vgapci0: Boot video device
pcib2: <ACPI PCI-PCI bridge> at device 6.0 on pci0
pci1: <ACPI PCI bus> on pcib2
pcib3: <ACPI PCI-PCI bridge> at device 6.2 on pci0
pci2: <ACPI PCI bus> on pcib3
nvme0: <Generic NVMe Device> mem 0x5e300000-0x5e303fff at device 0.0 on pci2
pcib4: <ACPI PCI-PCI bridge> at device 7.0 on pci0
xhci0: <Intel Alder Lake-P Thunderbolt 4 USB controller> mem 0x6104160000-0x610416ffff at device 13.0 on pci0
xhci0: 32 bytes context size, 64-bit DMA
xhci0: xECP capabilities <PROTO,PROTO,VEND(c0),LEGACY,VEND(c6),VEND(c7),VEND(c2),DEBUG,VEND(c3),VEND(d1),VEND(ce),VEND(c8),VEND(c9),VEND(ca),VEND(cc),VEND(cd),VEND(d2),VEND(cf),VEND(d3)>
usbus0 on xhci0
usbus0: 5.0Gbps Super Speed USB v3.0
pci0: <serial bus, USB> at device 13.2 (no driver attached)
xhci1: <Intel Alder Lake USB 3.2 controller> mem 0x5e480000-0x5e48ffff at device 20.0 on pci0
xhci1: 32 bytes context size, 64-bit DMA
xhci1: xECP capabilities <PROTO,PROTO,VEND(c0),LEGACY,VEND(c6),VEND(c7),VEND(c2),DEBUG,VEND(c3),VEND(c4),VEND(ce),VEND(c8),VEND(c9),VEND(ca),VEND(cb),VEND(cc),VEND(cd)>
usbus1: waiting for BIOS to give up control
xhci_interrupt: host controller halted
usbus1 on xhci1
usbus1: 5.0Gbps Super Speed USB v3.0
pci0: <memory, RAM> at device 20.2 (no driver attached)
pci0: <network> at device 20.3 (no driver attached)
pci0: <serial bus> at device 21.0 (no driver attached)
pci0: <serial bus> at device 21.1 (no driver attached)
pci0: <simple comms> at device 22.0 (no driver attached)
pcib5: <ACPI PCI-PCI bridge> at device 29.0 on pci0
pcib6: <ACPI PCI-PCI bridge> at device 29.1 on pci0
pci3: <ACPI PCI bus> on pcib6
re0: <RealTek 8168/8111 B/C/CP/D/DP/E/F/G PCIe Gigabit Ethernet> port 0x3000-0x30ff mem 0x5e204000-0x5e204fff,0x5e200000-0x5e203fff at device 0.0 on pci3
re0: Using 1 MSI-X message
re0: turning off MSI enable bit.
re0: ASPM disabled
re0: Chip rev. 0x54000000
re0: MAC rev. 0x00100000
miibus0: <MII bus> on re0
rgephy0: <RTL8251/8153 1000BASE-T media interface> PHY 1 on miibus0
rgephy0:  none, 10baseT, 10baseT-FDX, 10baseT-FDX-flow, 100baseTX, 100baseTX-FDX, 100baseTX-FDX-flow, 1000baseT-FDX, 1000baseT-FDX-master, 1000baseT-FDX-flow, 1000baseT-FDX-flow-master, auto, auto-flow
re0: Using defaults for TSO: 65518/35/2048
re0: Ethernet address: 9c:2d:cd:48:c3:c2
re0: netmap queues/slots: TX 1/256, RX 1/256
isab0: <PCI-ISA bridge> at device 31.0 on pci0
isa0: <ISA bus> on isab0
hdac0: <Intel Alder Lake-P HDA Controller> mem 0x6104178000-0x610417bfff,0x6104000000-0x61040fffff at device 31.3 on pci0
pci0: <serial bus> at device 31.5 (no driver attached)
acpi_acad0: <AC Adapter> on acpi0
acpi_lid0: <Control Method Lid Switch> on acpi0
acpi_button0: <Power Button> on acpi0
cpu0: <ACPI CPU> on acpi0
atkbdc0: <Keyboard controller (i8042)> port 0x60,0x64 irq 1 on acpi0
atkbd0: <AT Keyboard> irq 1 on atkbdc0
kbd0 at atkbd0
atkbd0: [GIANT-LOCKED]
acpi_syscontainer0: <System Container> on acpi0
battery0: <ACPI Control Method Battery> on acpi0
atrtc0: <AT realtime clock> at port 0x70 irq 8 on isa0
atrtc0: Warning: Couldn't map I/O.
atrtc0: registered as a time-of-day clock, resolution 1.000000s
atrtc0: Can't map interrupt.
atrtc0: non-PNP ISA device will be removed from GENERIC in FreeBSD 16.
hwpstate_intel0: <Intel Speed Shift> on cpu0
cpufreq0: <CPU frequency control> on cpu0
hwpstate_intel1: <Intel Speed Shift> on cpu1
cpufreq1: <CPU frequency control> on cpu1
hwpstate_intel2: <Intel Speed Shift> on cpu2
cpufreq2: <CPU frequency control> on cpu2
hwpstate_intel3: <Intel Speed Shift> on cpu3
cpufreq3: <CPU frequency control> on cpu3
hwpstate_intel4: <Intel Speed Shift> on cpu4
cpufreq4: <CPU frequency control> on cpu4
hwpstate_intel5: <Intel Speed Shift> on cpu5
cpufreq5: <CPU frequency control> on cpu5
hwpstate_intel6: <Intel Speed Shift> on cpu6
cpufreq6: <CPU frequency control> on cpu6
hwpstate_intel7: <Intel Speed Shift> on cpu7
cpufreq7: <CPU frequency control> on cpu7
hwpstate_intel8: <Intel Speed Shift> on cpu8
cpufreq8: <CPU frequency control> on cpu8
hwpstate_intel9: <Intel Speed Shift> on cpu9
cpufreq9: <CPU frequency control> on cpu9
hwpstate_intel10: <Intel Speed Shift> on cpu10
cpufreq10: <CPU frequency control> on cpu10
hwpstate_intel11: <Intel Speed Shift> on cpu11
cpufreq11: <CPU frequency control> on cpu11
hwpstate_intel12: <Intel Speed Shift> on cpu12
cpufreq12: <CPU frequency control> on cpu12
hwpstate_intel13: <Intel Speed Shift> on cpu13
cpufreq13: <CPU frequency control> on cpu13
hwpstate_intel14: <Intel Speed Shift> on cpu14
cpufreq14: <CPU frequency control> on cpu14
hwpstate_intel15: <Intel Speed Shift> on cpu15
cpufreq15: <CPU frequency control> on cpu15
hwpstate_intel16: <Intel Speed Shift> on cpu16
cpufreq16: <CPU frequency control> on cpu16
hwpstate_intel17: <Intel Speed Shift> on cpu17
cpufreq17: <CPU frequency control> on cpu17
hwpstate_intel18: <Intel Speed Shift> on cpu18
cpufreq18: <CPU frequency control> on cpu18
hwpstate_intel19: <Intel Speed Shift> on cpu19
cpufreq19: <CPU frequency control> on cpu19
Timecounters tick every 1.000 msec
ugen0.1: <Intel XHCI root HUB> at usbus0
ugen1.1: <Intel XHCI root HUB> at usbus1
uhub0 on usbus0
uhub0: <Intel XHCI root HUB, class 9/0, rev 3.00/1.00, addr 1> on usbus0
uhub1 on usbus1
uhub1: <Intel XHCI root HUB, class 9/0, rev 3.00/1.00, addr 1> on usbus1
hdacc0: <Realtek ALC257 HDA CODEC> at cad 0 on hdac0
hdaa0: <Realtek ALC257 Audio Function Group> at nid 1 on hdacc0
pcm0: <Realtek ALC257 (Analog 2.0+HP/2.0)> at nid 20,33 and 18 on hdaa0
pcm1: <Realtek ALC257 (Right Analog Mic)> at nid 25 on hdaa0
nda0 at nvme0 bus 0 scbus0 target 0 lun 1
nda0: <SKHynix_HFS001TEJ9X115N 51010A12 SSB5N610110605L2I>
nda0: Serial Number SSB5N610110605L2I
nda0: nvme version 1.4
nda0: 976762MB (2000409264 512 byte sectors)
Trying to mount root from ufs:/dev/nda0p7 [rw]...
uhub0: 2 ports with 2 removable, self powered
uhub1: 16 ports with 16 removable, self powered
ugen1.2: <GenesysLogic USB2.1 Hub> at usbus1
uhub2 on uhub1
uhub2: <GenesysLogic USB2.1 Hub, class 9/0, rev 2.10/23.11, addr 1> on usbus1
uhub2: MTT enabled
uhub2: 2 ports with 2 removable, self powered
ugen1.3: <ITE Tech. Inc. ITE Device(8910)> at usbus1
usbhid0 on uhub1
usbhid0: <ITE Tech. Inc. ITE Device(8910), class 0/0, rev 2.01/8.00, addr 2> on usbus1
hidbus0: <HID bus> on usbhid0
hkbd0: <ITE Tech. Inc. ITE Device(8910) Keyboard> on hidbus0
kbd2 at hkbd0
ugen1.4: <vendor 0x8087 product 0x0033> at usbus1
ugen1.5: <GenesysLogic USB3.2 Hub> at usbus1
uhub3 on uhub1
uhub3: <GenesysLogic USB3.2 Hub, class 9/0, rev 3.20/23.11, addr 4> on usbus1
uhub3: 2 ports with 2 removable, self powered
[drm] Got Intel graphics stolen memory base 0x4c800000, size 0x3c00000
drmn0: <drmn> on vgapci0
vgapci0: child drmn0 requested pci_enable_io
vgapci0: child drmn0 requested pci_enable_io
i915/adlp_dmc.bin: could not load binary firmware /boot/firmware/i915/adlp_dmc.bin either
adlp_dmc.bin: could not load binary firmware /boot/firmware/adlp_dmc.bin either
i915_adlp_dmc.bin: could not load binary firmware /boot/firmware/i915_adlp_dmc.bin either
drmn0: successfully loaded firmware image 'i915/adlp_dmc.bin'
drmn0: [drm] Finished loading DMC firmware i915/adlp_dmc.bin (v2.20)
lkpi_iic0: <LinuxKPI I2C> on drmn0
iicbus0: <Philips I2C bus> on lkpi_iic0
iic0: <I2C generic I/O> on iicbus0
lkpi_iic1: <LinuxKPI I2C> on drmn0
iicbus1: <Philips I2C bus> on lkpi_iic1
iic1: <I2C generic I/O> on iicbus1
lkpi_iic2: <LinuxKPI I2C> on drmn0
iicbus2: <Philips I2C bus> on lkpi_iic2
iic2: <I2C generic I/O> on iicbus2
lkpi_iic3: <LinuxKPI I2C> on drmn0
iicbus3: <Philips I2C bus> on lkpi_iic3
iic3: <I2C generic I/O> on iicbus3
lkpi_iic4: <LinuxKPI I2C> on drmn0
iicbus4: <Philips I2C bus> on lkpi_iic4
iic4: <I2C generic I/O> on iicbus4
lkpi_iic5: <LinuxKPI I2C> on drmn0
iicbus5: <Philips I2C bus> on lkpi_iic5
iic5: <I2C generic I/O> on iicbus5
lkpi_iic6: <LinuxKPI I2C> on drmn0
iicbus6: <Philips I2C bus> on lkpi_iic6
iic6: <I2C generic I/O> on iicbus6
lkpi_iic7: <LinuxKPI I2C> on drmn0
iicbus7: <Philips I2C bus> on lkpi_iic7
iic7: <I2C generic I/O> on iicbus7
lkpi_iic8: <LinuxKPI I2C> on drmn0
iicbus8: <Philips I2C bus> on lkpi_iic8
iic8: <I2C generic I/O> on iicbus8
drmn0: [drm] [ENCODER:244:DDI B/PHY B] unusable PPS, disabling eDP
i915/adlp_guc_70.bin: could not load binary firmware /boot/firmware/i915/adlp_guc_70.bin either
adlp_guc_70.bin: could not load binary firmware /boot/firmware/adlp_guc_70.bin either
i915_adlp_guc_70.bin: could not load binary firmware /boot/firmware/i915_adlp_guc_70.bin either
drmn0: successfully loaded firmware image 'i915/adlp_guc_70.bin'
i915/tgl_huc.bin: could not load binary firmware /boot/firmware/i915/tgl_huc.bin either
tgl_huc.bin: could not load binary firmware /boot/firmware/tgl_huc.bin either
i915_tgl_huc.bin: could not load binary firmware /boot/firmware/i915_tgl_huc.bin either
drmn0: successfully loaded firmware image 'i915/tgl_huc.bin'
drmn0: [drm] GT0: GuC firmware i915/adlp_guc_70.bin version 70.5.1
drmn0: [drm] GT0: HuC firmware i915/tgl_huc.bin version 7.9.3
drmn0: [drm] GT0: HuC: authenticated for all workloads
drmn0: [drm] GT0: GUC: submission disabled
drmn0: [drm] GT0: GUC: SLPC disabled
sysctl_add_oid: can't re-use a leaf (hw.dri.debug)!
lkpi_iic9: <LinuxKPI I2C> on drm1
iicbus9: <Philips I2C bus> on lkpi_iic9
iic9: <I2C generic I/O> on iicbus9
lkpi_iic10: <LinuxKPI I2C> on drm2
iicbus10: <Philips I2C bus> on lkpi_iic10
iic10: <I2C generic I/O> on iicbus10
lkpi_iic11: <LinuxKPI I2C> on drm3
iicbus11: <Philips I2C bus> on lkpi_iic11
iic11: <I2C generic I/O> on iicbus11
[drm] Initialized i915 1.6.0 20201103 for drmn0 on minor 0
VT: Replacing driver "efifb" with new "drmfb".
start FB_INFO:
height=1440 width=2560 depth=32
pbase=0x4000000000 vbase=0xfffffe018fc00000
name=drmn0 id=i915drmfb flags=0x0 stride=10240
end FB_INFO
iwx0: <Wi-Fi 6 AX211> mem 0x610417c000-0x610417ffff at device 20.3 on pci0
iwlwifi-so-a0-gf-a0-77.ucode: could not load firmware image, error 8
iwlwifi-so-a0-gf-a0.pnvm: could not load firmware image, error 8
iwx0: hw rev 0x370, fw 77.f92b5fed.0, pnvm 16611aa6, address 7c:b5:66:c7:54:20
iwx0: 11a rates: 6Mbps 9Mbps 12Mbps 18Mbps 24Mbps 36Mbps 48Mbps 54Mbps
iwx0: 11b rates: 1Mbps 2Mbps 5.5Mbps 11Mbps
iwx0: 11g rates: 1Mbps 2Mbps 5.5Mbps 11Mbps 6Mbps 9Mbps 12Mbps 18Mbps 24Mbps 36Mbps 48Mbps 54Mbps
iwx0: 2T2R
iwx0: 11na MCS 20MHz
iwx0: MCS 0-7: 6.5Mbps - 65Mbps
iwx0: MCS 8-15: 13Mbps - 130Mbps
iwx0: 11na MCS 20MHz SGI
iwx0: MCS 0-7: 7Mbps - 72Mbps
iwx0: MCS 8-15: 14.5Mbps - 144.5Mbps
iwx0: 11na MCS 40MHz:
iwx0: MCS 0-7: 13.5Mbps - 135Mbps
iwx0: MCS 8-15: 27Mbps - 270Mbps
iwx0: 11na MCS 40MHz SGI:
iwx0: MCS 0-7: 15Mbps - 150Mbps
iwx0: MCS 8-15: 30Mbps - 300Mbps
iwx0: 11ng MCS 20MHz
iwx0: MCS 0-7: 6.5Mbps - 65Mbps
iwx0: MCS 8-15: 13Mbps - 130Mbps
iwx0: 11ng MCS 20MHz SGI
iwx0: MCS 0-7: 7Mbps - 72Mbps
iwx0: MCS 8-15: 14.5Mbps - 144.5Mbps
iwx0: 11ng MCS 40MHz:
iwx0: MCS 0-7: 13.5Mbps - 135Mbps
iwx0: MCS 8-15: 27Mbps - 270Mbps
iwx0: 11ng MCS 40MHz SGI:
iwx0: MCS 0-7: 15Mbps - 150Mbps
iwx0: MCS 8-15: 30Mbps - 300Mbps
iwx0: [VHT] Channel Widths: 20MHz, 40MHz, 80MHz
iwx0: [VHT] Features: 31800020<SHORTGI80>
iwx0: [VHT] NSS 1: TX MCS 0..9, RX MCS 0..9
iwx0: [VHT] NSS 2: TX MCS 0..9, RX MCS 0..9
coretemp0: <CPU On-Die Thermal Sensors> on cpu0
ig4iic0: <Intel Alder Lake-P I2C Controller-0> at device 21.0 on pci0
ig4iic0: Using MSI
iicbus12: <Philips I2C bus (ACPI-hinted)> on ig4iic0
iic12: <I2C generic I/O> on iicbus12
ig4iic1: <Intel Alder Lake-P I2C Controller-1> at device 21.1 on pci0
ig4iic1: Using MSI
iicbus13: <Philips I2C bus (ACPI-hinted)> on ig4iic1
iicbus13: <unknown card> at addr 0x15
iic13: <I2C generic I/O> on iicbus13
ichsmb0: <Intel Alder Lake SMBus controller> port 0xefa0-0xefbf mem 0x6104184000-0x61041840ff at device 31.4 on pci0
smbus0: <System Management Bus> on ichsmb0
acpi_wmi0: <ACPI-WMI mapping> on acpi0
acpi_wmi0: Embedded MOF found
acpi_wmi1: <ACPI-WMI mapping> on acpi0
acpi_wmi1: Embedded MOF found
acpi_wmi2: <ACPI-WMI mapping> on acpi0
acpi_wmi2: Embedded MOF found
acpi_wmi3: <ACPI-WMI mapping> on acpi0
acpi_wmi3: Embedded MOF found
acpi_wmi4: <ACPI-WMI mapping> on acpi0
acpi_wmi4: Embedded MOF found
acpi_wmi5: <ACPI-WMI mapping> on acpi0
acpi_wmi5: Embedded MOF found
acpi_wmi6: <ACPI-WMI mapping> on acpi0
acpi_wmi6: Embedded MOF found
hcons0: <ITE Tech. Inc. ITE Device(8910) Consumer Control> on hidbus0
wlan0: Ethernet address: 7c:b5:66:c7:54:20
re0: link state changed to DOWN
lo0: link state changed to UP
wlan0: link state changed to UP
iichid0: <ELAN06FA:00 04F3:31AD I2C HID device> at addr 0x15 on iicbus13
iichid0: Using sampling mode
hidbus1: <HID bus> on iichid0
hms0: <ELAN06FA:00 04F3:31AD Mouse> on hidbus1
hms0: 2 buttons and [XY] coordinates ID=1
hmt0: <ELAN06FA:00 04F3:31AD TouchPad> on hidbus1
hconf0: <ELAN06FA:00 04F3:31AD Configuration> on hidbus1
hmt0: Multitouch touchpad with 0 external buttons, click-pad
hmt0: 5 contacts with [C] properties. Report range [0:0] - [3679:2261]
Security policy loaded: MAC/ntpd (mac_ntpd)

hw.i915kms values:
Code:
% cat /boot/loader.conf
hw.i915kms.enable_dpcd_backlight=0
hw.i915kms.enable_guc=2
hw.i915kms.invert_brightness=-1

% sysctl hw.i915kms
hw.i915kms.lmem_bar_size: 0
hw.i915kms.lmem_size: 0
hw.i915kms.request_timeout_ms: 20000
hw.i915kms.enable_dpcd_backlight: 0
hw.i915kms.enable_dp_mst: 1
hw.i915kms.guc_log_level: -1
hw.i915kms.enable_guc: 2
hw.i915kms.edp_vswing: 0
hw.i915kms.nuclear_pageflip: 0
hw.i915kms.verbose_state_checks: 1
hw.i915kms.mmio_debug: 0
hw.i915kms.memtest: 0
hw.i915kms.disable_display: 0
hw.i915kms.invert_brightness: -1
hw.i915kms.force_reset_modeset_test: 0
hw.i915kms.load_detect_test: 0
hw.i915kms.fastboot: -1
hw.i915kms.enable_dpt: 1
hw.i915kms.enable_ips: 1
hw.i915kms.disable_power_well: -1
hw.i915kms.enable_sagv: 1
hw.i915kms.enable_psr2_sel_fetch: 1
hw.i915kms.psr_safest_params: 0
hw.i915kms.enable_psr: -1
hw.i915kms.enable_hangcheck: 1
hw.i915kms.error_capture: 1
hw.i915kms.reset: 3
hw.i915kms.vbt_sdvo_panel_type: -1
hw.i915kms.panel_use_ssc: -1
hw.i915kms.lvds_channel_mode: 0
hw.i915kms.enable_fbc: -1
hw.i915kms.enable_dc: -1
hw.i915kms.modeset: -1

devinfo:
Code:
nexus0
  efirtc0
  smbios0
  cryptosoft0
  aesni0
  ram0
  apic0
  acpi0
    pcib0
      pci0
        hostb0
        pcib1
        vgapci0
          drmn0
                lkpi_iic9
                  iicbus9
                    iic9
                lkpi_iic10
                  iicbus10
                    iic10
                lkpi_iic11
                  iicbus11
                    iic11
            lkpi_iic0
              iicbus0
                iic0
            lkpi_iic1
              iicbus1
                iic1
            lkpi_iic2
              iicbus2
                iic2
            lkpi_iic3
              iicbus3
                iic3
            lkpi_iic4
              iicbus4
                iic4
            lkpi_iic5
              iicbus5
                iic5
            lkpi_iic6
              iicbus6
                iic6
            lkpi_iic7
              iicbus7
                iic7
            lkpi_iic8
              iicbus8
                iic8
        pcib2
          pci1
        pcib3
          pci2
            nvme0
        pcib4
        xhci0
          usbus0
            uhub0
        xhci1
          usbus1
            uhub1
              uhub2
              usbhid0
                hidbus0
                  hkbd0
                  hcons0
              uhub3
        iwx0
        ig4iic0
          iicbus12
            iic12
        ig4iic1
          iicbus13
            iichid0
              hidbus1
                hms0
                hmt0
                hconf0
            iic13
        pcib5
        pcib6
          pci3
            re0
              miibus0
                rgephy0
        isab0
          isa0
            atrtc0
        hdac0
          hdacc0
            hdaa0
              pcm0
              pcm1
        ichsmb0
          smbus0
    acpi_ec0
    battery0
    hpet0
    acpi_sysresource0
    atrtc1
    attimer0
    acpi_sysresource1
    atkbdc0
      atkbd0
    acpi_syscontainer0
    acpi_sysresource2
    acpi_wmi6
    acpi_sysresource3
    acpi_acad0
    acpi_lid0
    acpi_button0
    acpi_wmi0
    acpi_wmi1
    acpi_wmi2
    acpi_wmi3
    cpu0
      acpi_perf0
      hwpstate_intel0
      cpufreq0
      coretemp0
    cpu1
      acpi_perf1
      hwpstate_intel1
      cpufreq1
      coretemp1
    cpu2
      acpi_perf2
      hwpstate_intel2
      cpufreq2
      coretemp2
    cpu3
      acpi_perf3
      hwpstate_intel3
      cpufreq3
      coretemp3
    cpu4
      acpi_perf4
      hwpstate_intel4
      cpufreq4
      coretemp4
    cpu5
      acpi_perf5
      hwpstate_intel5
      cpufreq5
      coretemp5
    cpu6
      acpi_perf6
      hwpstate_intel6
      cpufreq6
      coretemp6
    cpu7
      acpi_perf7
      hwpstate_intel7
      cpufreq7
      coretemp7
    cpu8
      acpi_perf8
      hwpstate_intel8
      cpufreq8
      coretemp8
    cpu9
      acpi_perf9
      hwpstate_intel9
      cpufreq9
      coretemp9
    cpu10
      acpi_perf10
      hwpstate_intel10
      cpufreq10
      coretemp10
    cpu11
      acpi_perf11
      hwpstate_intel11
      cpufreq11
      coretemp11
    cpu12
      acpi_perf12
      hwpstate_intel12
      cpufreq12
      coretemp12
    cpu13
      acpi_perf13
      hwpstate_intel13
      cpufreq13
      coretemp13
    cpu14
      acpi_perf14
      hwpstate_intel14
      cpufreq14
      coretemp14
    cpu15
      acpi_perf15
      hwpstate_intel15
      cpufreq15
      coretemp15
    cpu16
      acpi_perf16
      hwpstate_intel16
      cpufreq16
      coretemp16
    cpu17
      acpi_perf17
      hwpstate_intel17
      cpufreq17
      coretemp17
    cpu18
      acpi_perf18
      hwpstate_intel18
      cpufreq18
      coretemp18
    cpu19
      acpi_perf19
      hwpstate_intel19
      cpufreq19
      coretemp19
    acpi_wmi4
    acpi_wmi5
    acpi_sysresource4
    acpi_timer0
 

Attachments

Have you tried without those settings?

Another thing you could try is: which drm-kmod is installed? : % pkg info -g 'drm*kmod'

If "drm-61-kmod" try graphics/drm-66-kmod.

Yeah, I added those to see if it works or not. dpcd_backlight was -1 by default and I tried 0 and 1 to test. I have drm-kmod right now (which should install drm-66-kmod) but I tried drm-latest-kmod too.
 
I just noticed something, My machine is dual-boot with Windows and FreeBSD, and when I boot FreeBSD my screen brightness changes to the last brightness I set when I was in Windows.
I guess it's worth noting that during boot, the screen brightness is higher when the device is in firmware and bootloader, and something dims the screen when FreeBSD kernel is loading ACPI.
This actually happened because last time I booted to Windows I had a brightness slightly lower than %100. Now that I booted to Windows and set the brightness to the %100 it doesn't happen anymore. If I like set the brightness to %10 in Windows and then reboot to FreeBSD I'll have that brightness, while still backlight reports 100 as my brightness.
 
I could dump GPU registers using graphics/igt-intel-tools ports, right now the backlight is set to %100 and this is the dump:
(The only backlight-related registers seem to be BLC_PWM_CTL and BLC_PWM_DATA)

Code:
BLC_PWM_CTL (0x00048250): 0x00000000 (enable 0, pipe A, blinking 0, granularity 128)
BLC_PWM_DATA (0x00048254): 0x00000001 (cycle 1, freq 0)
 

Attachments

I just noticed something, My machine is dual-boot with Windows and FreeBSD, and when I boot FreeBSD my screen brightness changes to the last brightness I set when I was in Windows.

This actually happened because last time I booted to Windows I had a brightness slightly lower than %100. Now that I booted to Windows and set the brightness to the %100 it doesn't happen anymore. If I like set the brightness to %10 in Windows and then reboot to FreeBSD I'll have that brightness, while still backlight reports 100 as my brightness.
Does the brightness level in Windows affects the level in FreeBSD only when the machine is warm rebooted (reboot the machine from windows into FreeBSD), or also in a cold reboot (machine powered off when in Windows, powered on, boot into FreeBSD)?
 
Both Cold Boot and Warm Boot are affected. Like I turned on my laptop after 2 days and booted into FreeBSD and saw it dims the screen, I couldn’t even remember that I had a lower brightness last time.
 
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