Smooth Scaling on 3440x1440 display: Large gap in available resolutions

[TcT2k]

I've a Mac mini (M1, 2020) connected to a Xiaomi Mi 34 Ultra Wide display 3440x1440 connected via HDMI.

When enabling the smooth resolution scale for the display the first step from the native resolution is below 1080.
With a dummy I'm using 2924x1224, which I've added as a custom resolution but it wont show up as HiDPI resolution.

See the screenshot below for the available resolutions:

I'm very satisfied with the dummy resolution but would prefer the native scaling for 100hz and DRM video playback.
Is there any way to enable resolutions between native 1440 and the 1066 available or is this a hardware limitation?

[waydabber]

Resolutions below 3072 should be available with an entry level M1 at 60Hz. With 100Hz there might be stricter hardware limitations but I did not test it. Can you try 60Hz?

[TcT2k]

Thanks for the fast reply.
I've tested setting to 60hz, but it looks basically the same (except for 60Hz).

I didn't reboot after switching to 60hz, could that make a difference?

Maybe it would be different with display port, but I don't have the necessary adapter (USB-C -> DisplayPort) at hand.

[waydabber]

Yes, it would be interesting to try with DisplayPort. I did not do tests regarding resolution limits with the HDMI port so I am not sure. Hopefully others will chime in with their experiences. The M1 Mini should support higher HiDPI native resolutions, it is not entirely obvious to me why is it capped at 2546x1066.

[TcT2k]

I was able to test with a USBC to HDMI adapter and got additional resolutions. I'm waiting for a USBC to Displayport adapter, but it seems to make a difference if I use HDMI or USBC

[TcT2k]

I've now received a USBC to DisplayPort cable and there is a much larger selection in resolutions and refresh rates (but the monitor only supports > 100hz on DisplayPort).

So there is a difference between the built in HDMI port and using USB-C to DisplayPort or HDMI.

[waydabber]

Yes, if smooth scaling works properly, you should get something like this in the resolution menu (but with smooth scaling I think it is more convenient to use the resolution slider).

[brypwn]

Hi @TcT2k, how did you get to that settings screen? I have the same monitor as you but all I see is a percentage rather than a list of resolutions.

Thanks!

[waydabber]

You can change the slider from percentage to resolution by selecting this:

You can change the slider to a resolution submenu with detailed resolution info by changing the selector type to submenu and enabling all subsequent options:

(note these screenshots are taken from an unreleased beta which have slightly more options but those matter only on the latest Ventura beta anyway)