This bug might need reassigning to the kernel instead.
I'm guessing that (like Mir) the mode-setting driver doesn't invent in-between modes like Xorg drivers do (and like legacy VGA BIOS's do for old CRTs)
Please run this command to see if the kernel is the one failing to report those modes: grep . /sys/class/drm/*/modes
This bug might need reassigning to the kernel instead.
I'm guessing that (like Mir) the mode-setting driver doesn't invent in-between modes like Xorg drivers do (and like legacy VGA BIOS's do for old CRTs)
Please run this command to see if the kernel is the one failing to report those modes: drm/*/modes
grep . /sys/class/