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#1 2025-12-30 12:17:35

themusicalduck
Member
Registered: 2011-07-04
Posts: 141

No backlight control. No HDR. Lenovo Legion Pro 7 Gen 10.

Edit2: I went back to dedicated mode because hybrid was causing issues with an external display, so I'm still interested in trying to figure out why the brightness won't work. Though I read online it could be a bug with nvidia drivers, so I might be out of luck anyway.

Edit: Brightness works in hybrid mode and hybrid mode actually seems to be reliable (I assumed it wouldn't be) so the brightness problem is solved for now.

I still can't figure out how to get HDR to work though.

Also, the integrated GPU is AMD:

08:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Granite Ridge [Radeon Graphics] (rev d4)

------------------------------------------

I have a new laptop that mostly works, but I can't get backlight control to work and there is no option to enable HDR on the inbuilt screen.

I have a secondary monitor where HDR and backlight control works fine, just not the internal screen.

GPU is: 01:00.0 VGA compatible controller: NVIDIA Corporation GB203M / GN22-X9 [GeForce RTX 5080 Max-Q / Mobile] (rev a1)

I'm running it in dedicated mode only for now and using the nvidia-open driver.

I'm using Gnome with wayland and controlling brightness with the built in slider.

Output of ddcutil detect:

Invalid display
   I2C bus:  /dev/i2c-8
   DRM_connector:           card1-eDP-1
   EDID synopsis:
      Mfg id:               SDC - Samsung Display Corp.
      Model:                ATNA60HU02-0
      Product code:         16923  (0x421b)
      Serial number:
      Binary serial number: 0 (0x00000000)
      Manufacture year:     2024,  Week: 0
   This monitor does not support DDC/CI. (I2C slave address x37 is unresponsive.)

I can see that on the internal display it says "This monitor does not support DDC/CI. (I2C slave address x37 is unresponsive.)"

I tried adding amdgpu.backlight=0 and then amdgpu.backlight=1 to boot options but it made no difference. I also tried acpi_backlight=native/video/vendor but no difference on any of those.

Output of cat /sys/class/drm/card1-eDP-1/edid | edid-decode:

edid-decode (hex):

00 ff ff ff ff ff ff 00 4c 83 1b 42 00 00 00 00
00 22 01 04 b5 22 16 78 03 66 85 ae 51 38 b9 24
0a 50 54 00 00 00 01 01 01 01 01 01 01 01 01 01
01 01 01 01 01 01 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 fd 0c 30 f0 b1
b1 73 01 0a 20 20 20 20 20 20 00 00 00 fe 00 53
44 43 20 20 20 20 20 20 20 20 20 20 00 00 00 fc
00 41 54 4e 41 36 30 48 55 30 32 2d 30 20 02 a9

70 20 79 02 00 20 00 0c ba 41 59 1b 42 00 00 00
00 00 18 00 22 00 28 00 67 11 85 ff 09 4f 00 07
00 1f 00 3f 06 c7 00 7f 00 07 00 00 67 11 05 ff
09 4f 00 07 00 1f 00 3f 06 df 15 97 15 07 00 21
00 1d 74 0d 69 08 00 0a 40 06 00 e5 7a 51 85 a3
b9 4a 02 0a 02 45 54 d0 5f 4c 64 00 45 23 78 81
00 14 73 1a 00 00 03 0b 30 f0 00 a0 8f 01 6a 02
f0 00 00 00 00 8d 00 00 00 00 00 00 00 00 0a 90

70 20 79 00 00 2b 00 0c 27 00 3c ef 00 00 27 00
30 3b 00 00 2e 00 06 00 45 d0 5f 4c 64 81 00 0b
e3 05 80 00 e6 06 05 01 8f 6a 01 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 14 90

----------------

Block 0, Base EDID:
  EDID Structure Version & Revision: 1.4
  Vendor & Product Identification:
    Manufacturer: SDC
    Model: 16923
    Made in: 2024
  Basic Display Parameters & Features:
    Digital display
    Bits per primary color channel: 10
    DisplayPort interface
    Maximum image size: 34 cm x 22 cm
    Gamma: 2.20
    Supported color formats: RGB 4:4:4
    First detailed timing includes the native pixel format and preferred refresh rate
    Display supports continuous frequencies
  Color Characteristics:
    Red  : 0.6806, 0.3183
    Green: 0.2197, 0.7246
    Blue : 0.1425, 0.0390
    White: 0.3134, 0.3291
  Established Timings I & II: none
  Standard Timings: none
  Detailed Timing Descriptors:
    Empty Descriptor
    Display Range Limits:
      Monitor ranges (Range Limits Only): 48-240 Hz V, 432-432 kHz H, max dotclock 1150 MHz
    Alphanumeric Data String: 'SDC          '
    Display Product Name: 'ATNA60HU02-0 '
  Extension blocks: 2
Checksum: 0xa9

----------------

Block 1, DisplayID Extension Block:
  Version: 2.0
  Extension Count: 0
  Display Product Primary Use Case: None of the listed primary use cases; generic display
  Product Identification Data Block (0x20), OUI BA-41-59:
    Product Code: 16923
    Year of Manufacture: 2024
  Video Timing Modes Type 7 - Detailed Timings Data Block:
    DTD:  2560x1600  240.000210 Hz  16:10   432.000 kHz   1140.481000 MHz (aspect 16:10, no 3D stereo, preferred)
               Hfront    8 Hsync  32 Hback   40 Hpol N
               Vfront  128 Vsync   8 Vback   64 Vpol N
    DTD:  2560x1600   60.000053 Hz  16:10   432.000 kHz   1140.481000 MHz (aspect 16:10, no 3D stereo)
               Hfront    8 Hsync  32 Hback   40 Hpol N
               Vfront 5528 Vsync   8 Vback   64 Vpol N
  Display Parameters Data Block (0x21):
    Image size: 344.4 mm x 215.3 mm
    Display native pixel format: 2560x1600
    Scan Orientation: Left to Right, Top to Bottom
    Luminance Information: Minimum guaranteed value
    Color Information: CIE 1931
    Audio Speaker Information: integrated
    Native Color Chromaticity:
      Primary #1:  (0.680908, 0.318115)
      Primary #2:  (0.219971, 0.725098)
      Primary #3:  (0.143066, 0.039062)
      White Point: (0.312988, 0.329102)
    Native Maximum Luminance (Full Coverage): 500.000000 cd/m^2
    Native Maximum Luminance (10% Rectangular Coverage): 1100.000000 cd/m^2
    Native Minimum Luminance: 5.000000 cd/m^2
    Native Color Depth: 12 bpc
    Display Device Technology: Organic LED
    Native Gamma EOTF: 2.20
  CTA-861 DisplayID Data Block:
  Vendor-Specific Data Block (AMD), OUI 00-00-1A:
    Version: 3
    Feature Caps: 0x0b
    Minimum Refresh Rate: 48 Hz
    Maximum Refresh Rate: 240 Hz
    Flags 1.x: 0x00
    Flags 2.x: 0xa0
    Maximum luminance: 143 (1107.128 cd/m^2)
    Minimum luminance: 1 (0.000 cd/m^2)
    Unknown: 0x6a 0x02
  Checksum: 0x0a
Checksum: 0x90

----------------

Block 2, DisplayID Extension Block:
  Version: 2.0
  Extension Count: 0
  Adaptive Sync Data Block:
    Descriptor #1:
      Native Panel Range
      Fixed Average V-Total and Adaptive V-Total
      Supports Seamless Transition
      'Max Single Frame Duration Increase' field value without jitter impact
      'Max Single Frame Duration Decrease' field value without jitter impact
      Max Duration Increase: 0.00 ms
      Max Duration Decrease: 0.00 ms
      Min Refresh Rate: 60 Hz
      Max Refresh Rate: 240 Hz
    Descriptor #2:
      Native Panel Range
      Fixed Average V-Total and Adaptive V-Total
      Supports Seamless Transition
      'Max Single Frame Duration Increase' field value without jitter impact
      'Max Single Frame Duration Decrease' field value without jitter impact
      Max Duration Increase: 0.00 ms
      Max Duration Decrease: 0.00 ms
      Min Refresh Rate: 48 Hz
      Max Refresh Rate: 60 Hz
  Brightness Luminance Range Data Block:
    Minimum SDR Luminance (Full Coverage): 5.000000 cd/m^2
    Maximum Suggested SDR Luminance (Full Coverage): 500.000000 cd/m^2
    Maximum Boost SDR Luminance: 500.000000 cd/m^2
  CTA-861 DisplayID Data Block:
  Colorimetry Data Block:
    BT2020RGB
  HDR Static Metadata Data Block:
    Electro optical transfer functions:
      Traditional gamma - SDR luminance range
      SMPTE ST2084
    Supported static metadata descriptors:
      Static metadata type 1
    Desired content max luminance: 143 (1107.128 cd/m^2)
    Desired content max frame-average luminance: 106 (496.743 cd/m^2)
    Desired content min luminance: 1 (0.000 cd/m^2)
  Checksum: 0x14
Checksum: 0x90

Suggests that HDR is possible, but when I open display settings on Gnome, there is no option to enable it. That option exists for my secondary monitor however.

Last edited by themusicalduck (2026-01-01 19:22:25)

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#2 2025-12-30 12:50:44

karabaja4
Member
From: Croatia
Registered: 2008-09-14
Posts: 1,035
Website

Re: No backlight control. No HDR. Lenovo Legion Pro 7 Gen 10.

I don't know if this is helpful as I'm not using GNOME, but I have the same laptop (275HX and 5090) and I wrote this script that I bound to a key to control the brightness:

https://github.com/karabaja4/arch/blob/ … ghtness.sh
use like: "brightness.sh 1" for up and "brightness.sh -1" for down.

Does it work for you?

Last edited by karabaja4 (2025-12-30 12:52:21)

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#3 2025-12-30 13:09:53

themusicalduck
Member
Registered: 2011-07-04
Posts: 141

Re: No backlight control. No HDR. Lenovo Legion Pro 7 Gen 10.

I did try running:

echo 20 | sudo tee /sys/class/backlight/nvidia_0/brightness

and it made no difference, which I think is the same as your script.

Thanks anyway.

I noticed that if the laptop is in hybrid mode then brightness does work, I'd still like to find out if it can work in dedicated mode though.

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#4 2025-12-30 18:10:33

seth
Member
From: Don't DM me only for attention
Registered: 2012-09-03
Posts: 72,067

Re: No backlight control. No HDR. Lenovo Legion Pro 7 Gen 10.

Fuck, should have read to the end first…

I'm running it in dedicated mode only for now and using the nvidia-open driver.
…
I noticed that if the laptop is in hybrid mode then brightness does work

Sill, 

brightnessctl -l

let's see what's actually there/detected - but it's possible that the nvidia GPU cannot control the backlight at all.

-----------------

https://wiki.archlinux.org/title/NVIDIA … ss_control
Did you install nvidia-bl-dkms for this?

NVIDIA Corporation GB203M / GN22-X9 [GeForce RTX 5080 Max-Q / Mobile

I tried adding amdgpu.backlight=0 and then amdgpu.backlight=1

and karabaja4's script links an intel device lol

lspci -k
brightnessctl -l

If this is an optimus system, the eDP is typically wired to the IGP, so you'd be operating on the intel device.

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#5 2025-12-30 18:29:08

themusicalduck
Member
Registered: 2011-07-04
Posts: 141

Re: No backlight control. No HDR. Lenovo Legion Pro 7 Gen 10.

seth wrote:

Fuck, should have read to the end first…

I'm running it in dedicated mode only for now and using the nvidia-open driver.
…
I noticed that if the laptop is in hybrid mode then brightness does work

Sill, 

brightnessctl -l

let's see what's actually there/detected - but it's possible that the nvidia GPU cannot control the backlight at all.

-----------------

https://wiki.archlinux.org/title/NVIDIA … ss_control
Did you install nvidia-bl-dkms for this?

NVIDIA Corporation GB203M / GN22-X9 [GeForce RTX 5080 Max-Q / Mobile

I tried adding amdgpu.backlight=0 and then amdgpu.backlight=1

and karabaja4's script links an intel device lol

lspci -k
brightnessctl -l

If this is an optimus system, the eDP is typically wired to the IGP, so you'd be operating on the intel device.

Sorry about that I gotta edit the post to properly reflect current state.

I see your point but actually the iGPU is AMD hence trying those options in case of some conflict happening >.< (a detail I forgot to mention).

Thanks for the link. I will try that if I go back to dedicated mode. Actually I assumed hybrid mode wouldn't work well hence turning that feature off, but so far it has been fine, so I might just stick with it.

I'm still stuck on how to enable HDR though.

Last edited by themusicalduck (2025-12-30 18:29:32)

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#6 2025-12-30 18:43:26

seth
Member
From: Don't DM me only for attention
Registered: 2012-09-03
Posts: 72,067

Re: No backlight control. No HDR. Lenovo Legion Pro 7 Gen 10.

nvidia-bl-dkms is probably bitrot and disfunct - rather don't install that.

What does the EDID look like in the hybrid mode?

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#7 2025-12-30 21:59:14

themusicalduck
Member
Registered: 2011-07-04
Posts: 141

Re: No backlight control. No HDR. Lenovo Legion Pro 7 Gen 10.

Here is the current EDID in hybrid mode:

➜  drm cat card2/card2-eDP-1/edid | edid-decode
edid-decode (hex):

00 ff ff ff ff ff ff 00 4c 83 1b 42 00 00 00 00
00 22 01 04 b5 22 16 78 03 66 85 ae 51 38 b9 24
0a 50 54 00 00 00 01 01 01 01 01 01 01 01 01 01
01 01 01 01 01 01 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 fd 0c 30 f0 b1
b1 73 01 0a 20 20 20 20 20 20 00 00 00 fe 00 53
44 43 20 20 20 20 20 20 20 20 20 20 00 00 00 fc
00 41 54 4e 41 36 30 48 55 30 32 2d 30 20 02 a9

70 20 79 02 00 20 00 0c ba 41 59 1b 42 00 00 00
00 00 18 00 22 00 28 00 67 11 85 ff 09 4f 00 07
00 1f 00 3f 06 c7 00 7f 00 07 00 00 67 11 05 ff
09 4f 00 07 00 1f 00 3f 06 df 15 97 15 07 00 21
00 1d 74 0d 69 08 00 0a 40 06 00 e5 7a 51 85 a3
b9 4a 02 0a 02 45 54 d0 5f 4c 64 00 45 23 78 81
00 14 73 1a 00 00 03 0b 30 f0 00 a0 8f 01 6a 02
f0 00 00 00 00 8d 00 00 00 00 00 00 00 00 0a 90

70 20 79 00 00 2b 00 0c 27 00 3c ef 00 00 27 00
30 3b 00 00 2e 00 06 00 45 d0 5f 4c 64 81 00 0b
e3 05 80 00 e6 06 05 01 8f 6a 01 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 14 90

----------------

Block 0, Base EDID:
  EDID Structure Version & Revision: 1.4
  Vendor & Product Identification:
    Manufacturer: SDC
    Model: 16923
    Made in: 2024
  Basic Display Parameters & Features:
    Digital display
    Bits per primary color channel: 10
    DisplayPort interface
    Maximum image size: 34 cm x 22 cm
    Gamma: 2.20
    Supported color formats: RGB 4:4:4
    First detailed timing includes the native pixel format and preferred refresh rate
    Display supports continuous frequencies
  Color Characteristics:
    Red  : 0.6806, 0.3183
    Green: 0.2197, 0.7246
    Blue : 0.1425, 0.0390
    White: 0.3134, 0.3291
  Established Timings I & II: none
  Standard Timings: none
  Detailed Timing Descriptors:
    Empty Descriptor
    Display Range Limits:
      Monitor ranges (Range Limits Only): 48-240 Hz V, 432-432 kHz H, max dotclock 1150 MHz
    Alphanumeric Data String: 'SDC          '
    Display Product Name: 'ATNA60HU02-0 '
  Extension blocks: 2
Checksum: 0xa9

----------------

Block 1, DisplayID Extension Block:
  Version: 2.0
  Extension Count: 0
  Display Product Primary Use Case: None of the listed primary use cases; generic display
  Product Identification Data Block (0x20), OUI BA-41-59:
    Product Code: 16923
    Year of Manufacture: 2024
  Video Timing Modes Type 7 - Detailed Timings Data Block:
    DTD:  2560x1600  240.000210 Hz  16:10   432.000 kHz   1140.481000 MHz (aspect 16:10, no 3D stereo, preferred)
               Hfront    8 Hsync  32 Hback   40 Hpol N
               Vfront  128 Vsync   8 Vback   64 Vpol N
    DTD:  2560x1600   60.000053 Hz  16:10   432.000 kHz   1140.481000 MHz (aspect 16:10, no 3D stereo)
               Hfront    8 Hsync  32 Hback   40 Hpol N
               Vfront 5528 Vsync   8 Vback   64 Vpol N
  Display Parameters Data Block (0x21):
    Image size: 344.4 mm x 215.3 mm
    Display native pixel format: 2560x1600
    Scan Orientation: Left to Right, Top to Bottom
    Luminance Information: Minimum guaranteed value
    Color Information: CIE 1931
    Audio Speaker Information: integrated
    Native Color Chromaticity:
      Primary #1:  (0.680908, 0.318115)
      Primary #2:  (0.219971, 0.725098)
      Primary #3:  (0.143066, 0.039062)
      White Point: (0.312988, 0.329102)
    Native Maximum Luminance (Full Coverage): 500.000000 cd/m^2
    Native Maximum Luminance (10% Rectangular Coverage): 1100.000000 cd/m^2
    Native Minimum Luminance: 5.000000 cd/m^2
    Native Color Depth: 12 bpc
    Display Device Technology: Organic LED
    Native Gamma EOTF: 2.20
  CTA-861 DisplayID Data Block:
  Vendor-Specific Data Block (AMD), OUI 00-00-1A:
    Version: 3
    Feature Caps: 0x0b
    Minimum Refresh Rate: 48 Hz
    Maximum Refresh Rate: 240 Hz
    Flags 1.x: 0x00
    Flags 2.x: 0xa0
    Maximum luminance: 143 (1107.128 cd/m^2)
    Minimum luminance: 1 (0.000 cd/m^2)
    Unknown: 0x6a 0x02
  Checksum: 0x0a
Checksum: 0x90

----------------

Block 2, DisplayID Extension Block:
  Version: 2.0
  Extension Count: 0
  Adaptive Sync Data Block:
    Descriptor #1:
      Native Panel Range
      Fixed Average V-Total and Adaptive V-Total
      Supports Seamless Transition
      'Max Single Frame Duration Increase' field value without jitter impact
      'Max Single Frame Duration Decrease' field value without jitter impact
      Max Duration Increase: 0.00 ms
      Max Duration Decrease: 0.00 ms
      Min Refresh Rate: 60 Hz
      Max Refresh Rate: 240 Hz
    Descriptor #2:
      Native Panel Range
      Fixed Average V-Total and Adaptive V-Total
      Supports Seamless Transition
      'Max Single Frame Duration Increase' field value without jitter impact
      'Max Single Frame Duration Decrease' field value without jitter impact
      Max Duration Increase: 0.00 ms
      Max Duration Decrease: 0.00 ms
      Min Refresh Rate: 48 Hz
      Max Refresh Rate: 60 Hz
  Brightness Luminance Range Data Block:
    Minimum SDR Luminance (Full Coverage): 5.000000 cd/m^2
    Maximum Suggested SDR Luminance (Full Coverage): 500.000000 cd/m^2
    Maximum Boost SDR Luminance: 500.000000 cd/m^2
  CTA-861 DisplayID Data Block:
  Colorimetry Data Block:
    BT2020RGB
  HDR Static Metadata Data Block:
    Electro optical transfer functions:
      Traditional gamma - SDR luminance range
      SMPTE ST2084
    Supported static metadata descriptors:
      Static metadata type 1
    Desired content max luminance: 143 (1107.128 cd/m^2)
    Desired content max frame-average luminance: 106 (496.743 cd/m^2)
    Desired content min luminance: 1 (0.000 cd/m^2)
  Checksum: 0x14
Checksum: 0x90

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#8 2025-12-30 22:56:10

themusicalduck
Member
Registered: 2011-07-04
Posts: 141

Re: No backlight control. No HDR. Lenovo Legion Pro 7 Gen 10.

I had a go at following this post:

https://bbs.archlinux.org/viewtopic.php … 9#p2277349

but I think I need to change the script to make it work with mine and I'm too dumb to know how to do it.

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#9 2025-12-31 00:22:02

seth
Member
From: Don't DM me only for attention
Registered: 2012-09-03
Posts: 72,067

Re: No backlight control. No HDR. Lenovo Legion Pro 7 Gen 10.

#!/usr/bin/env python3
with open("edid.bin", "rb") as f:
    original = bytearray(f.read())

block0 = bytearray(original[0:128])
block1 = bytearray(original[128:256])
block2 = bytearray(original[256:384])

# Update extension count 1 -> 2
block0[0x7E] = 0x02

# Recalculate Block 0 checksum
block0[0x7F] = 0
block0[0x7F] = (256 - (sum(block0) % 256)) % 256

# Create CTA-861 block with HDR data copied from DisplayID block
cta = bytearray(128)
cta[0:4] = [0x02, 0x03, 0x23, 0x00]  # CTA header
cta[4:24] = original[0x120:0x120+20]   # AMD VSDB (FreeSync)
cta[24:28] = original[0x134:0x134+4]   # Colorimetry (BT2020RGB)
cta[28:35] = original[0x138:0x138+7]   # HDR Static Metadata

# CTA checksum
cta[127] = (256 - (sum(cta) % 256)) % 256

patched = bytes(block0) + bytes(block1) + bytes(block2) + bytes(cta)
with open("edid-patched-hdr.bin", "wb") as f:
    f.write(patched)

print(f"Patched EDID saved: {len(patched)} bytes")

http://0x0.st/P-TY.bin

…
Block 3, CTA-861 Extension Block:                                                                                                                                                                                                                          
  Revision: 3                                                                                                                                                                                                                                              
  Native detailed modes: 0                                                                                                                                                                                                                                 
  Colorimetry Data Block:                                                                                                                                                                                                                                  
    BT2020RGB                                                                                                                                                                                                                                              
  HDR Static Metadata Data Block:                                                                                                                                                                                                                          
    Electro optical transfer functions:                                                                                                                                                                                                                    
      Traditional gamma - SDR luminance range                                                                                                                                                                                                              
      SMPTE ST2084                                                                                                                                                                                                                                         
    Supported static metadata descriptors:                                                                                                                                                                                                                 
      Static metadata type 1                                                                                                                                                                                                                               
    Desired content max luminance: 143 (1107.128 cd/m^2)                                                                                                                                                                                                   
    Desired content max frame-average luminance: 106 (496.743 cd/m^2)                                                                                                                                                                                      
    Desired content min luminance: 1 (0.000 cd/m^2)                                                                                                                                                                                                        
  Unknown CTA-861 Data Block (tag 0x00, length 0):                                                                                                                                                                                                         
  Unknown CTA-861 Data Block (tag 0x00, length 0):                                                                                                                                                                                                         
  Unknown CTA-861 Data Block (tag 0x00, length 0):                                                                                                                                                                                                         
  Unknown CTA-861 Data Block (tag 0x00, length 0):                                                                                                                                                                                                         
  Unknown CTA-861 Data Block (tag 0x00, length 0):                                                                              
  Unknown CTA-861 Data Block (tag 0x00, length 0):                                                                              
  Unknown CTA-861 Data Block (tag 0x00, length 0):                                                                              
  Unknown CTA-861 Data Block (tag 0x00, length 0):                                                                              
  Unknown CTA-861 Data Block (tag 0x00, length 0):                                                                              
  Unknown CTA-861 Data Block (tag 0x00, length 0):                                                                              
  Unknown CTA-861 Data Block (tag 0x00, length 0):                                                                              
  Unknown CTA-861 Data Block (tag 0x00, length 0):                                                                              
  Unknown CTA-861 Data Block (tag 0x00, length 0):                                                                              
  Unknown CTA-861 Data Block (tag 0x00, length 0):                                                                              
  Unknown CTA-861 Data Block (tag 0x00, length 0):                                                                              
  Unknown CTA-861 Data Block (tag 0x00, length 0):                                                                              
  Unknown CTA-861 Data Block (tag 0x00, length 0):                                                                              
  Unknown CTA-861 Data Block (tag 0x00, length 0):                                                                              
  Unknown CTA-861 Data Block (tag 0x00, length 0):                                                                              
  Unknown CTA-861 Data Block (tag 0x00, length 0):                                                                              
Checksum: 0x84  Unused space in Extension Block: 92 bytes

no idea whether that tail would be a problem

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#10 2025-12-31 02:20:50

themusicalduck
Member
Registered: 2011-07-04
Posts: 141

Re: No backlight control. No HDR. Lenovo Legion Pro 7 Gen 10.

Thanks so much for the new script.

I think the tail does break it unfortunately:

[    1.839374] amdgpu 0000:08:00.0: [drm] *ERROR* Invalid firmware EDID "edid/edp-hdr.bin"
[    1.840670] amdgpu 0000:08:00.0: [drm] *ERROR* Invalid firmware EDID "edid/edp-hdr.bin"

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#11 2025-12-31 10:31:32

seth
Member
From: Don't DM me only for attention
Registered: 2012-09-03
Posts: 72,067

Re: No backlight control. No HDR. Lenovo Legion Pro 7 Gen 10.

Not sure whether that's actually the problem, see https://en.wikipedia.org/wiki/Extended_ … ata_format and if I copy more bytes from the 2nd block nothing changes (because they're also all 0x0) and google has several hits for "Unknown CTA-861 Data Block" from actual hardware EDIDs
Can you change the edid at runtime?
Also 

md5sum /usr/lib/edid/edp-hdr.bin"

(Should be b2404fb842b7352a16695188c5edcd30) and make sure the edid was added to the initramfs if the amdgpu module is there

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#12 2025-12-31 18:06:30

themusicalduck
Member
Registered: 2011-07-04
Posts: 141

Re: No backlight control. No HDR. Lenovo Legion Pro 7 Gen 10.

Yes my md5sum matches yours.

In /etc/mkinitcpio.conf I added it to FILES like so:

FILES=(/lib/firmware/edid/edp-hdr.bin)

and regenerated with sudo mkinitcpio -P

It seems like it is possible to write to the edid at runtime, but it doesn't like the patched one:

cat /lib/firmware/edid/edp-hdr.bin > /sys/kernel/debug/dri/1/eDP-1/edid_override
cat: write error: Invalid argument

by comparison if I do the same with the original unpatched extracted bin, it completes successfully and prints nothing.

I also went back to using dedicated graphics because I was experiencing lag with an external display in hybrid mode. Maybe if I can get HDR working for proper colour management, I can use some software solution to change the brightness (since it's an oled screen).

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#13 2025-12-31 19:22:00

seth
Member
From: Don't DM me only for attention
Registered: 2012-09-03
Posts: 72,067

Re: No backlight control. No HDR. Lenovo Legion Pro 7 Gen 10.

While playing around w/ it I must have set the updated block count back to two at some point.
Try http://0x0.st/P-eP.bin

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#14 2025-12-31 20:35:44

themusicalduck
Member
Registered: 2011-07-04
Posts: 141

Re: No backlight control. No HDR. Lenovo Legion Pro 7 Gen 10.

No luck with that one sadly. My screen stays blank and it isn't recognised in gnome settings. No errors in dmesg this time.

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#15 2025-12-31 23:34:25

seth
Member
From: Don't DM me only for attention
Registered: 2012-09-03
Posts: 72,067

Re: No backlight control. No HDR. Lenovo Legion Pro 7 Gen 10.

Since the 2nd block doesn't look particularly interesting, we could just replace that: http://0x0.st/P-Ls.bin

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#16 2026-01-01 06:08:54

themusicalduck
Member
Registered: 2011-07-04
Posts: 141

Re: No backlight control. No HDR. Lenovo Legion Pro 7 Gen 10.

Same result unfortunately. A blank screen.

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#17 2026-01-01 08:58:34

seth
Member
From: Don't DM me only for attention
Registered: 2012-09-03
Posts: 72,067

Re: No backlight control. No HDR. Lenovo Legion Pro 7 Gen 10.

Do you lose the output overall or just in gnome?
Can you start an X11 session (openbox) or sway/weston/hyprland/etc. w/ that EDID?

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#18 2026-01-01 17:53:57

themusicalduck
Member
Registered: 2011-07-04
Posts: 141

Re: No backlight control. No HDR. Lenovo Legion Pro 7 Gen 10.

I do still get output on boot up until it tries to start GDM.

I do get output on openbox but not on hyprland.

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#19 2026-01-01 19:44:27

seth
Member
From: Don't DM me only for attention
Registered: 2012-09-03
Posts: 72,067

Re: No backlight control. No HDR. Lenovo Legion Pro 7 Gen 10.

Did you enable HDR on hyprland? What if you don't? Does the edid then produce ouput?
https://wiki.archlinux.org/title/HDR#Hyprland

Edit, x-ref: https://bbs.archlinux.org/viewtopic.php?id=311382

Last edited by seth (2026-01-01 19:47:53)

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#20 2026-01-04 17:41:22

themusicalduck
Member
Registered: 2011-07-04
Posts: 141

Re: No backlight control. No HDR. Lenovo Legion Pro 7 Gen 10.

I had a look in my hyperland.conf and there is no reference to xx_color_management_v4 so it looks like it was not trying to use HDR then.

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#21 2026-01-04 20:34:33

seth
Member
From: Don't DM me only for attention
Registered: 2012-09-03
Posts: 72,067

Re: No backlight control. No HDR. Lenovo Legion Pro 7 Gen 10.

https://wiki.hypr.land/Configuring/Monitors/#monitor-v2
Override the setting and force it to

{
…
supports_wide_color = -1
supports_hdr = -1
…
}

off

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