Unable to get capabilities for LG Ultrafine 22MD4KA - VCP detection failed

[Merlin04]

I'm encountering an error when trying to detect the capabilities of my LG Ultrafine 22MD4KA monitor. When I run sudo ddcutil detect I get:

[...]
Display 2
   I2C bus:  /dev/i2c-15
   DRM connector:           card1-DP-2
   EDID synopsis:
      Mfg id:               GSM - Goldstar Company Ltd (LG)
      Model:                LG UltraFine
      Product code:         23312  (0x5b10)
      Serial number:        801NTEP9M516
      Binary serial number: 327516 (0x0004ff5c)
      Manufacture year:     2018,  Week: 1
   VCP version:         Detection failed

and when running sudo ddcutil -d 2 -v capabilities I get:

/dev/i2c-15, Feature 0xdd should not exist, but the monitor reports it as valid
Feature definition file not found: GSM-LG_UltraFine-23312.mccs
VCP (aka MCCS) version for display is undetected or less than 2.0. Interpretation may not be accurate.
Unable to get capabilities for monitor on Display_Handle[i2c-15: fd=3].  Maximum DDC retries exceeded.

Using ddcutil to control the brightness of the monitor works fine, but prints the VCP error again:

> sudo ddcutil -d 2 setvcp 10 45
VCP (aka MCCS) version for display is undetected or less than 2.0. Interpretation may not be accurate.

Here's my ddcutil-interrogate.log.

[rockowitz]

Do you know if the errors occurred for ddcutil 1.4.5 or earlier?

Does using option --disable-dynamic-sleep resolve the problems?

What is the output from ddcutil capabilities --display 2 --trcfunc get_capabilities_info_buffer --excp

What is the output from ddcutil --display 2 getvcp df --verbose --excp

[rockowitz]

User @adlr encountered a similar situation with LG Ultrafine monitors in issue #468. The monitor reports that feature xDF (Vcp Version) is unsupported. So the message:

VCP (aka MCCS) version for display is undetected or less than 2.0. Interpretation may not be accurate.

is correct. However, it does not provide information relevant to command setvcp. It should only be reported only in the output of commands such as getvcp that need to interpret feature values.

[SinTrans]

I'm also encountering this error. --disable-dynamic-sleep didn't seem to resolve the problem.

$ sudo ddcutil --disable-dynamic-sleep detect   

[...]
Display 1                                                                                                            
   I2C bus:  /dev/i2c-14                                                                                             
   DRM connector:           card1-DP-1                                                                               
   EDID synopsis:                                                                                                    
      Mfg id:               GSM - Goldstar Company Ltd (LG)                                                          
      Model:                LG UltraFine                                                                             
      Product code:         23419  (0x5b7b)                                                                          
      Serial number:        201NTUWGL126                                                                             
      Binary serial number: 564126 (0x00089b9e)                                                                      
      Manufacture year:     2022,  Week: 1                                                                           
   VCP version:         Detection failed       

$ sudo ddcutil capabilities --display 1 --trcfunc get_capabilities_info_buffer --excp                                
Traced function not found: get_capabilities_info_buffer          

$ sudo ddcutil --display 1 getvcp df --verbose --excp
Feature definition file not found: GSM-LG_UltraFine-23419.mccs
VCP (aka MCCS) version for display is undetected or less than 2.0. Interpretation may not be accurate.

Getting data for non-table VCP code 0xdf - VCP Version:
VCP code 0xdf (VCP Version                   ): Unsupported feature code
(ddc_get_formatted_value_for_dfm) Freeing exception:
   Exception in function ddc_get_nontable_vcp_value: status=DDCRC_REPORTED_UNSUPPORTED(-3005): DDC reports facility unsupported
      Unsupported feature