usb power

[felipepanza]

Hi how can my Mac mini m1 send usb power to a monitor Dell P2917HC with usb cable? It is connected with HDMI and I can't use usb c connection because Luna Display dongle is connected already in one of the two usb c.

Here are the specs for the monitor:

Input Connectors
1 HDMI port
1 DP(in) port
1 DP(out) port
1 USB Type-C port
2 USB 2.0 downstream ports (rear)
2 USB 3.0 downstream ports (side)

 

[joevt]

The Dell display has its own power supply. It is not powered by USB.

The Mac mini has its own power supply. It is not powered by USB.

If you want to use the USB downstream ports of the display, then you should connect a USB-A to USB-C cable from one of the Mac mini's USB-A ports because if you use a USB-C to USB-C cable then you may interfere with the Luna Display dongle since the M1 Macs can only output to one display from the Thunderbolt ports.

I don't know if USB-A to USB-C will work when using HDMI. You'll have to try it to find out. You might want to set the "Auto Select for USB-C" option to "No". Also, set "MST" to "OFF".

If this doesn't work, then use USB-C to USB-C for the Dell and move the Luna Display to the HDMI port using an HDMI to DisplayPort or USB/C adapter.
https://www.club-3d.com/en/detail/2517/hdmi_to_usb_c_4k60hz_active_adapter_m-f/
https://www.club-3d.com/en/detail/2491/hdmit_to_displayportt_4k60hz_m-f_active_adapter/

There's a HDMI Luna Display for Windows. I wonder why they don't advertise it for macOS?

 

[felipepanza]

You are right I want to use the USB downstream, sorry for my bad English.

Are you sure Lunda display will work with HMDI to USB C?

 

[lcubed]

silly question, will the luna display dongle work if plugged into the downstream usb port of the monitor and the monitor is connected by the usb-c to the mini?

 

[joevt]

Are you sure Lunda display will work with HMDI to USB C?

I don't have Luna display or an HDMI to USB-C adapter so I don't know.

silly question, will the luna display dongle work if plugged into the downstream usb port of the monitor and the monitor is connected by the usb-c to the mini?

I believe @felipepanza has the USB-C version of the Luna Display. Luna Display also has a MiniDisplayPort and HDMI version. They say the Luna Display acts as a real display because it connects to the GPU like a real display. That leads me to believe that the USB-C version uses DisplayPort Alt Mode so it cannot work from USB-A.

The Dell display has a downstream DisplayPort, but it cannot be used with macOS because macOS doesn't support MST for multiple displays even on Intel Macs.

The Dell display has downstream USB ports, so you could use DisplayLink adapter. I wonder if DisplayLink + Luna Display could work? DisplayLink removes the direct GPU benefit. But with M1 Macs, that may be its own benefit since M1 Macs can only connect 1 or 2 displays to directly to GPU. I wonder what the quality of DisplayLink + Luna Display would be like? They both use compression which might not be good combined together.