[lug] Dell Optiplex 9020 + ubuntu + 4k monitor

[Zan Lynx]

On 11/7/19 10:13 AM, Bear Giles wrote:
> It's all 4k-ready HDMI. This hardware was driving the monitor at 4k with
> an old ubuntu version that had been release-update'd a few times. It
> only broke when I did a fresh install of 19.10.

There are ways to provide an EDID override to the Linux graphics system.
With a fresh install it may have defaulted to the new (newer anyway)
modeset drivers which handle all of the graphics setup in kernel instead
of in an X.org driver. Wayland requires using the modeset drivers too.

Depending on the monitor it may have been relying on a X.org modeline or
EDID override that got deleted with your fresh install.

Some monitors don't claim their advanced features in EDID because nobody
trusts anybody else to handle compatibility correctly. There might be a
configuration option in the monitor's setup menus to choose higher
levels of HDMI. It might even depend on which HDMI port on the monitor
or TV you are plugged into, if there is more than one.

The EDID overrides are funny that way because they replace what the
monitor or TV reports. But the TV will usually accept anything it will
work with, even if it didn't advertise it.

On my LG 4K televisions, they require turning on HDMI Deep Color on the
HDMI port, or you cannot do 60 Hz 4K. It is silly, but what they call
Deep Color is actually all of HDMI 2.0.

And I had an early 4K Dell monitor that only used DisplayPort, and you
had to go into the settings to enable DP 1.2 or it wouldn't do 4K at all.

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