Mac mini 2018 + Dell P2415Q = noop

[bismark]

Following setup:

• Mac mini (2018)
• macOS 10.14.1
• Dell P2415Q
  • HDMI 2.0 enabled
• Connected over HDMI

Setting the brightness/contrast appears to just do nothing 🙁

Output from a debug build:

$ ./ddcctl -d 1 -b 42 -c 26
2018-12-02 23:30:37.003 ddcctl[2043:40754] D: NSScreen #724070914 (1920x1080 0°) HiDPI
2018-12-02 23:30:37.003 ddcctl[2043:40754] I: found 1 external display
2018-12-02 23:30:37.003 ddcctl[2043:40754] I: polling display 1's EDID

Framebuffer: AppleIntelFramebuffer
IOService:/AppleACPIPlatformExpert/PCI0@0/AppleACPIPCI/IGPU@2/AppleIntelFramebuffer@2/display0/AppleDisplay
VN:4268 PN:41157 SN:825312066 UN:2 IN:14083 Serial:

2018-12-02 23:30:37.010 ddcctl[2043:40754] I: got edid.serial: G3D7F89Q11CB
2018-12-02 23:30:37.010 ddcctl[2043:40754] I: got edid.name: DELL P2415Q
2018-12-02 23:30:37.010 ddcctl[2043:40754] D: action: b: 42
2018-12-02 23:30:37.010 ddcctl[2043:40754] D: setting VCP control #16 => 42

Framebuffer: AppleIntelFramebuffer
IOService:/AppleACPIPlatformExpert/PCI0@0/AppleACPIPCI/IGPU@2/AppleIntelFramebuffer@2/display0/AppleDisplay
VN:4268 PN:41157 SN:825312066 UN:2 IN:14371 Serial:

2018-12-02 23:30:37.138 ddcctl[2043:40754] D: action: c: 26
2018-12-02 23:30:37.138 ddcctl[2043:40754] D: setting VCP control #18 => 26

Framebuffer: AppleIntelFramebuffer
IOService:/AppleACPIPlatformExpert/PCI0@0/AppleACPIPCI/IGPU@2/AppleIntelFramebuffer@2/display0/AppleDisplay
VN:4268 PN:41157 SN:825312066 UN:2 IN:17715 Serial:

[kfix]

Oh shoot, was thinking about getting the new MM.
So its just Intel Graphics inside?
Have any other monitors worked over the HDMI port?
How about via USB3 ports using dongles (🤢 )?

[sse1234]

I'm also facing problems with the MM 2018 and an Eizo EV2785.

When connected via USB-C, I receive an error and adjustments aren't performed:

$ ./ddcctl -d 1 -b 30
2018-12-18 10:02:27.710 ddcctl[10670:1714365] D: NSScreen #1892340716 (2560x1440 0°) HiDPI
2018-12-18 10:02:27.710 ddcctl[10670:1714365] I: found 1 external display
2018-12-18 10:02:27.710 ddcctl[10670:1714365] I: polling display 1's EDID

Framebuffer: AppleIntelFramebuffer
IOService:/AppleACPIPlatformExpert/PCI0@0/AppleACPIPCI/IGPU@2/AppleIntelFramebuffer@0/display0/AppleDisplay
VN:5571 PN:10513 SN:32348078 UN:0 IN:14083 Serial:

2018-12-18 10:02:27.722 ddcctl[10670:1714365] I: got edid.name: EV2785
2018-12-18 10:02:27.722 ddcctl[10670:1714365] D: action: b: 30
2018-12-18 10:02:27.722 ddcctl[10670:1714365] D: setting VCP control #16 => 30

Framebuffer: AppleIntelFramebuffer
IOService:/AppleACPIPlatformExpert/PCI0@0/AppleACPIPCI/IGPU@2/AppleIntelFramebuffer@0/display0/AppleDisplay
VN:5571 PN:10513 SN:32348078 UN:0 IN:18451 Serial:

2018-12-18 10:02:27.770 ddcctl[10670:1714365] E: Failed to send DDC command!

When connected via HDMI, I receive no error, but adjustments aren't performed either:

$ ./ddcctl -d 1 -b 30
2018-12-18 10:06:22.283 ddcctl[11125:1723309] D: NSScreen #1892340398 (2560x1440 0°) HiDPI
2018-12-18 10:06:22.283 ddcctl[11125:1723309] I: found 1 external display
2018-12-18 10:06:22.283 ddcctl[11125:1723309] I: polling display 1's EDID

Framebuffer: AppleIntelFramebuffer
IOService:/AppleACPIPlatformExpert/PCI0@0/AppleACPIPCI/IGPU@2/AppleIntelFramebuffer@2/display0/AppleDisplay
VN:5571 PN:10516 SN:32348078 UN:2 IN:12547 Serial:

2018-12-18 10:06:22.289 ddcctl[11125:1723309] I: got edid.name: EV2785
2018-12-18 10:06:22.289 ddcctl[11125:1723309] D: action: b: 30
2018-12-18 10:06:22.289 ddcctl[11125:1723309] D: setting VCP control #16 => 30

Framebuffer: AppleIntelFramebuffer
IOService:/AppleACPIPlatformExpert/PCI0@0/AppleACPIPCI/IGPU@2/AppleIntelFramebuffer@2/display0/AppleDisplay
VN:5571 PN:10516 SN:32348078 UN:2 IN:16679 Serial:

@kfix I have a Mac Mini 2018 here that I was able to test, and ddcctl works only over a USB-C to HDMI adapter that uses DisplayPort Alt Mode (tested with a Plugable-branded one). No dice on the built-in HDMI port (although it can read the display's serial number and looks like it's working, but the monitor does not appear to be receiving the signal since its OSD stays up when a command is sent instead of disappearing).

I have a theory that the Mini is using HDMI Alt Mode or something weird for its built-in HDMI port, as it shows up as "DisplayPort" audio output in the Sound preferences. If it were DP Alt Mode it would probably be working (?) given successes with the adapter.

That stated, as of 10.14.6 using the DP adapter instead of the built-in port also means that FileVault can't be used and the Apple logo does not display on boot up. Looks like Apple's missing EFI support for DP out or something. :/ But display control does work. Sometimes it takes a few tries, but it works. I2C timings can be annoying.

[kfix]

I have the AmazonBasics DP<->USB-C converter on my MM2018 and am getting crashes, assuming #42 minReplyDelay changes for AMD are causing that.

interesting observation about the OSD!

[damoen]

Facing the same problem on my Mac mini (2018) connected to 43UN700-B via HDMI.

[tealord]

Same problem here with the Mac Mini 2018 and the LG34UC97 via HDMI. Setting the brightness and volume when the display is connected via Thunderbolt works fine.

[kambala-decapitator]

same issue with HDMI to HDMI on BenQ GW2765, works fine with USB-C to DP