Same issue for me on an ThinkPad X1 extreme (gen 2), EDID info:
# edid-decode /sys/class/drm/card0-eDP-1/edid [09:29:37] Extracted contents: header: 00 ff ff ff ff ff ff 00 serial number: 4c 83 41 41 00 00 00 00 13 1d version: 01 04 basic params: b5 22 13 78 02 chroma info: 94 91 ae 51 3e b7 24 0b 50 54 established: 00 00 00 standard: 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 descriptor 1: f0 d4 00 40 f1 70 18 80 30 20 44 00 58 c2 10 00 00 1b descriptor 2: f0 d4 00 40 f1 70 18 80 30 20 44 00 58 c2 10 00 00 1b descriptor 3: 00 00 00 0f 00 ff 09 3c ff 09 3c 2c 80 00 00 00 00 00 descriptor 4: 00 00 00 fe 00 41 54 4e 41 35 36 57 52 30 38 2d 30 20 extensions: 01 checksum: 15 Manufacturer: SDC Model 4141 Serial Number 0 Made week 19 of 2019 EDID version: 1.4 Digital display 10 bits per primary color channel DisplayPort interface Maximum image size: 34 cm x 19 cm Gamma: 2.20 Supported color formats: RGB 4:4:4 First detailed timing is preferred timing Established timings supported: Standard timings supported: Detailed mode: Clock 545.120 MHz, 344 mm x 194 mm 3840 3888 3920 4160 hborder 0 2160 2164 2168 2184 vborder 0 +hsync -vsync Detailed mode: Clock 545.120 MHz, 344 mm x 194 mm 3840 3888 3920 4160 hborder 0 2160 2164 2168 2184 vborder 0 +hsync -vsync Manufacturer-specified data, tag 15 ASCII string: ATNA56WR08-0 Has 1 extension blocks Checksum: 0x15 (valid) CEA extension block Extension version: 3 11 bytes of CEA data Extended tag: Colorimetry data block xvYCC601 xvYCC709 sYCC601 AdobeYCC601 AdobeRGB BT2020cYCC BT2020YCC BT2020RGB Extended tag: HDR static metadata data block Electro optical transfer functions: Traditional gamma - SDR luminance range Traditional gamma - HDR luminance range SMPTE ST2084 Supported static metadata descriptors: Static metadata type 1 Desired content max luminance: 115 Desired content max frame-average luminance: 109 Desired content min luminance: 7 0 native detailed modes Checksum: 0xab (valid) EDID block does NOT conform to EDID 1.3! Missing name descriptor Missing monitor ranges Detailed block string not properly terminated -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1831587 Title: brightness control not work with OLED panel To manage notifications about this bug go to: https://bugs.launchpad.net/hwe-next/+bug/1831587/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs