rockowitz
commented
4 years ago Displays vary in how they implement DDC when multiple monitors are attached. Feature code x60 is particularly problematic. For some, setvcp works only if issued from the device whose input is selected. That is, ddcutil or ClickMonitorDDC work only if issued on the currently selected input. For others, setvcp 60 works no matter what the input.
I assume since you mention ClickMonitorDDC that you're running Windows in a VM. So as a first step, check whether ddcutil setvcp 60 or ClickMonitorDDC work when used on the currently active input.
DisplayPort connections are also problematic. Can you configure so that DVI or HDMI, not DisplayPort, is used for the 29UM69G?
Finally, LG monitors, particularly Ultrawide monitors, have been seen to depart from the DDC standard. See the description of "LG Ultrawide" in http://www.ddcutil.com/monitor_notes, which includes the following:
"When responding to a Get VCP Feature request, the monitor never sets the Result Code field of the VCP Feature Reply to Unsupported VCP Code. Instead, it always reports No Error. For unsupported VCP codes, all bytes in the response (MH, ML, SH, SL) are set to x00."
So that's the explanation for the x00 response you're seeing. ddcutil tries to figure out if a display (pathologically) uses an all 0 response to indicate unsupported, but it's a heuristic test and isn't perfect. If the answer is yes, that is stated in the monitor description.
The test that is reported by the "Supports DDC" line in the monitor description has been eliminated. It was a simple test that probed slave address x37 without actually trying to communicate. That was found to not always be accurate. Instead, ddcutil simply uses whether DDC protocol communication works. If it does, you see the "VCP version" line, if not there a message that the display does not support DDC.
Please run command "ddcutil interrogate" when the input is set to the source of the command, and send the output as an attachment.
Sanford
On 12/14/19 7:55 AM, jonpas wrote:
LG 29UM69G fails at switching monitor inputs. I did not try other capabilities. Performing |$ ddcutil --display setvcp 2 60 0x[0f|11]| simply flashes the screen, but nothing changes.
|$ ddcutil detect ... Display 2 I2C bus: /dev/i2c-6 EDID synopsis: Mfg id: GSM Model: LG ULTRAWIDE Serial number: Manufacture year: 2019 EDID version: 1.3 VCP version: 2.1 |
There is no |Supports DDC: [true|false]| in the output.
|$ ddcutil environment| shows all permissions are correct (read & write).
|$ ddcutil --display 2 getvcp 60 VCP code 0x60 (Input Source ): Invalid value (sl=0x00) |
This shows up correctly as |VGA-1 (sl=0x01)| for display 1 (secondary monitor).
|$ ddcutil capabilities --display 2 --verbose ... Unparsed capabilities string: (prot(monitor)type(lcd)UM69cmds(01 02 03 0C E3 F3)vcp(02 04 05 08 10 12 14(05 08 0B ) 16 18 1A 52 60( 11 0F 10) AC AE B2 B6 C0 C6 C8 C9 D6(01 04) DF 62 8D F4 F5(01 02 03 04) F6(00 01 02) 4D 4E 4F 15(01 06 11 13 14 15 18 19 20 22 23 24 28 29 32 48) F7(00 01 02 03) F8(00 01) F9 E4 E5 E6 E7 E8 E9 EA EB EF FA(00 01) FD(00 01) FE(00 01 02) FF)mccs_ver(2.1)mswhql(1)) ... Feature: 60 (Input Source) Values (unparsed): 11 0F 10 Values ( parsed): 0f: DisplayPort-1 10: DisplayPort-2 11: HDMI-1 |
ClickMonitorDDC on Windows has the same issue of reporting |0x00| and not being able to switch.
Both monitors are connected to both an integrated GPU (Intel CPU) and dedicated GPU (GTX 1060) in the following way (VFIO setup):
- Display 1 (secondary): o VGA -> iGPU o DVI -> dGPU
- Display 2 (primary, LG 29UM69G): o HDMI -> iGPU o DisplayPort -> dGPU
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LG 29UM69G fails at switching monitor inputs. I did not try other capabilities. Performing
$ ddcutil --display 2 setvcp 60 0x[0f|11]simply flashes the screen, but nothing changes.There is no
Supports DDC: [true|false]in the output.$ ddcutil environmentshows all permissions are correct (read & write).This shows up correctly as
VGA-1 (sl=0x01)for display 1 (secondary monitor).ClickMonitorDDC on Windows has the same issue of reporting
0x00and not being able to switch.Both monitors are connected to both an integrated GPU (Intel CPU) and dedicated GPU (GTX 1060) in the following way (VFIO setup):
Thank you in advance!