Backlight doesn't work on drm-kmod 5.10 or 5/26 master

[neelchauhan]

Describe the bug

On an Intel TigerLake system, I am unable to use the backlight on drm-kmod 5.10. Older drm-kmod releases, until v5.9_2 worked fine.

FreeBSD version

neel@concorde:~ % uname -a

FreeBSD concorde.neelc.org 14.0-CURRENT FreeBSD 14.0-CURRENT #1 main-n255824-20b2b464ebb: Thu May 26 00:03:21 PDT 2022 neel@concorde.neelc.org:/usr/obj/usr/src/amd64.amd64/sys/GENERIC-NODEBUG amd64

PCI Info

pciconf -lv

hostb0@pci0:0:0:0: class=0x060000 rev=0x01 hdr=0x00 vendor=0x8086 device=0x9a14 subvendor=0x103c subdevice=0x87f7 vendor = 'Intel Corporation' device = '11th Gen Core Processor Host Bridge/DRAM Registers' class = bridge subclass = HOST-PCI vgapci0@pci0:0:2:0: class=0x030000 rev=0x01 hdr=0x00 vendor=0x8086 device=0x9a49 subvendor=0x103c subdevice=0x87f7 vendor = 'Intel Corporation' device = 'TigerLake-LP GT2 [Iris Xe Graphics]' class = display subclass = VGA none0@pci0:0:4:0: class=0x118000 rev=0x01 hdr=0x00 vendor=0x8086 device=0x9a03 subvendor=0x103c subdevice=0x87f7 vendor = 'Intel Corporation' device = 'TigerLake-LP Dynamic Tuning Processor Participant' class = dasp pcib1@pci0:0:7:0: class=0x060400 rev=0x01 hdr=0x01 vendor=0x8086 device=0x9a23 subvendor=0x103c subdevice=0x87f6 vendor = 'Intel Corporation' device = 'Tiger Lake-LP Thunderbolt 4 PCI Express Root Port' class = bridge subclass = PCI-PCI pcib2@pci0:0:7:1: class=0x060400 rev=0x01 hdr=0x01 vendor=0x8086 device=0x9a25 subvendor=0x103c subdevice=0x87f6 vendor = 'Intel Corporation' device = 'Tiger Lake-LP Thunderbolt 4 PCI Express Root Port' class = bridge subclass = PCI-PCI none1@pci0:0:8:0: class=0x088000 rev=0x01 hdr=0x00 vendor=0x8086 device=0x9a11 subvendor=0x103c subdevice=0x87f7 vendor = 'Intel Corporation' device = 'GNA Scoring Accelerator module' class = base peripheral xhci0@pci0:0:13:0: class=0x0c0330 rev=0x01 hdr=0x00 vendor=0x8086 device=0x9a13 subvendor=0x103c subdevice=0x87f7 vendor = 'Intel Corporation' device = 'Tiger Lake-LP Thunderbolt 4 USB Controller' class = serial bus subclass = USB none2@pci0:0:13:2: class=0x0c0340 rev=0x01 hdr=0x00 vendor=0x8086 device=0x9a1b subvendor=0x2222 subdevice=0x1111 vendor = 'Intel Corporation' device = 'Tiger Lake-LP Thunderbolt 4 NHI' class = serial bus subclass = USB pcib3@pci0:0:14:0: class=0x010400 rev=0x00 hdr=0x00 vendor=0x8086 device=0x9a0b subvendor=0x8086 subdevice=0x0000 vendor = 'Intel Corporation' device = 'Volume Management Device NVMe RAID Controller' class = mass storage subclass = RAID none3@pci0:0:18:0: class=0x070000 rev=0x20 hdr=0x00 vendor=0x8086 device=0xa0fc subvendor=0x103c subdevice=0x87f7 vendor = 'Intel Corporation' device = 'Tiger Lake-LP Integrated Sensor Hub' class = simple comms subclass = UART xhci1@pci0:0:20:0: class=0x0c0330 rev=0x20 hdr=0x00 vendor=0x8086 device=0xa0ed subvendor=0x103c subdevice=0x87f7 vendor = 'Intel Corporation' device = 'Tiger Lake-LP USB 3.2 Gen 2x1 xHCI Host Controller' class = serial bus subclass = USB none4@pci0:0:20:2: class=0x050000 rev=0x20 hdr=0x00 vendor=0x8086 device=0xa0ef subvendor=0x103c subdevice=0x87f7 vendor = 'Intel Corporation' device = 'Tiger Lake-LP Shared SRAM' class = memory subclass = RAM iwlwifi0@pci0:0:20:3: class=0x028000 rev=0x20 hdr=0x00 vendor=0x8086 device=0xa0f0 subvendor=0x8086 subdevice=0x0074 vendor = 'Intel Corporation' device = 'Wi-Fi 6 AX201' class = network ig4iic0@pci0:0:21:0: class=0x0c8000 rev=0x20 hdr=0x00 vendor=0x8086 device=0xa0e8 subvendor=0x103c subdevice=0x87f7 vendor = 'Intel Corporation' device = 'Tiger Lake-LP Serial IO I2C Controller' class = serial bus ig4iic1@pci0:0:21:1: class=0x0c8000 rev=0x20 hdr=0x00 vendor=0x8086 device=0xa0e9 subvendor=0x103c subdevice=0x87f7 vendor = 'Intel Corporation' device = 'Tiger Lake-LP Serial IO I2C Controller' class = serial bus none5@pci0:0:22:0: class=0x078000 rev=0x20 hdr=0x00 vendor=0x8086 device=0xa0e0 subvendor=0x103c subdevice=0x87f7 vendor = 'Intel Corporation' device = 'Tiger Lake-LP Management Engine Interface' class = simple comms pcib6@pci0:0:28:0: class=0x060400 rev=0x20 hdr=0x01 vendor=0x8086 device=0xa0bd subvendor=0x103c subdevice=0x87f7 vendor = 'Intel Corporation' device = 'Tigerlake PCH-LP PCI Express Root Port' class = bridge subclass = PCI-PCI none6@pci0:0:29:0: class=0x088000 rev=0x00 hdr=0x00 vendor=0x8086 device=0x09ab subvendor=0x103c subdevice=0x87f6 vendor = 'Intel Corporation' class = base peripheral isab0@pci0:0:31:0: class=0x060100 rev=0x20 hdr=0x00 vendor=0x8086 device=0xa082 subvendor=0x103c subdevice=0x87f7 vendor = 'Intel Corporation' device = 'Tiger Lake-LP LPC Controller' class = bridge subclass = PCI-ISA hdac0@pci0:0:31:3: class=0x040100 rev=0x20 hdr=0x00 vendor=0x8086 device=0xa0c8 subvendor=0x103c subdevice=0x87f6 vendor = 'Intel Corporation' device = 'Tiger Lake-LP Smart Sound Technology Audio Controller' class = multimedia subclass = audio ichsmb0@pci0:0:31:4: class=0x0c0500 rev=0x20 hdr=0x00 vendor=0x8086 device=0xa0a3 subvendor=0x103c subdevice=0x87f7 vendor = 'Intel Corporation' device = 'Tiger Lake-LP SMBus Controller' class = serial bus subclass = SMBus none7@pci0:0:31:5: class=0x0c8000 rev=0x20 hdr=0x00 vendor=0x8086 device=0xa0a4 subvendor=0x103c subdevice=0x87f7 vendor = 'Intel Corporation' device = 'Tiger Lake-LP SPI Controller' class = serial bus pcib4@pci65532:224:29:0: class=0x060400 rev=0x20 hdr=0x01 vendor=0x8086 device=0xa0b0 subvendor=0x103c subdevice=0x87f7 vendor = 'Intel Corporation' device = 'Tiger Lake-LP PCI Express Root Port' class = bridge subclass = PCI-PCI pcib5@pci65532:224:29:2: class=0x060400 rev=0x20 hdr=0x01 vendor=0x8086 device=0xa0b2 subvendor=0x103c subdevice=0x87f7 vendor = 'Intel Corporation' class = bridge subclass = PCI-PCI nvme0@pci65532:225:0:0: class=0x010802 rev=0x03 hdr=0x00 vendor=0x8086 device=0x0975 subvendor=0x8086 subdevice=0x8410 vendor = 'Intel Corporation' class = mass storage subclass = NVM nvme1@pci65532:226:0:0: class=0x010802 rev=0x00 hdr=0x00 vendor=0x8086 device=0x0975 subvendor=0x8086 subdevice=0x8510 vendor = 'Intel Corporation' class = mass storage subclass = NVM rtsx0@pci0:87:0:0: class=0xff0000 rev=0x01 hdr=0x00 vendor=0x10ec device=0x525a subvendor=0x103c subdevice=0x87f7 vendor = 'Realtek Semiconductor Co., Ltd.' device = 'RTS525A PCI Express Card Reader'

DRM KMOD version

Both drm-510-kmod 5.10.113 and e229eef88b2dea3eab966b1ca52009682733ef3 as of 5/26.

To Reproduce Steps to reproduce the behavior:

Take a Intel TigerLake system using DPCD backlight

The TigerLake HP Spectre x360 14 is a good example as I use this system. I can't speak for the newer AlderLake model, however.

Screenshots

N/A

Additional context

System: HP Spectre x360 14-ea0023dx. This system requires the DPCD backlight. Backlight got broken with the drm-kmod 5.10 update. Don't know if it's DPCD or not, everything else I have (personal and work) uses 8th Gen.

[evadot]

Could you bisect ?

[neelchauhan]

Sorry for taking so long to respond. I cannot bisect as 5.9 does not compile on recent CURRENTs.

[uqs]

I too have non-working acpi_video after upgrading my 13-STABLE system overnight.

/boot/kernel.old is from Aug 20th and I was running the fbsd13-kmod thing from Aug20th as well. Now I got a kernel from today and drm-510-kmod-5.10.113_8

This is on a Thinkpad T490

[evadot]

Use backlight(8)

[uqs]

Perfect, thank you!

[evadot]

@neelchauhan do you still have this problem ?

[evadot]

Closing as we have no news from original reporter.