Rates are saved per display (EDID ID) and loaded by the hotplug script
for whichever display is connected. The item is on only while the
connected display is boosted; unticking removes just that one. The app
lists the saved displays and removes any of them (hdmi-forget).
The EDID override moves off the kernel command line to a hotplug script
(boot unit + udev rule) that loads it only while the display it was
tested on is connected, identified over DDC; other displays get their
own EDID.
Set up… opens a screen with the display, its resolution and the rates on
offer. The display's own faster mode is switched to right away; the other
rates can each be tried live (wait for the picture, keep within 15 s or it
switches back) and ticked; Install installs the ticked ones through
apply --hdmi. All rates are loaded when the screen opens, so a try is only a
mode switch. Also fixes switching back to a rate like 59.97 Hz.
The pinned 7.1.6 kernel doesn't read the extra EDID block (HDMI Forum
EEODB) where monitors list their fast modes, and does no HDMI 2.1, so HDMI
displays often stay at 60 Hz. The new menu item reads the display's EDID
over DDC, calculates the highest rate that fits HDMI 2.0 at the desktop
resolution (rounded down to ten, plus the hundred below as a safe option),
tests each step live with a confirmation, and makes the confirmed ones
permanent through drm.edid_firmware (Limine, sdboot-manage or GRUB).
theupriser