drm_kms_helper.edid_firmware=edid/your_edid.bin

"Boot with standard options+edid"  "ro root=UUID=70cadff3-f077-4d1d-8533-bd56aee7c14c splash=silent quiet showopts drm_kms_helper.edid_firmware=/edid/MacBookPro_11_2_edid.bin"

"Boot with standard options+edid"  "ro root=UUID=70cadff3-f077-4d1d-8533-bd56aee7c14c splash=silent quiet showopts drm_kms_helper.edid_firmware=/usr/lib/firmware/edid/MacBookPro_11_2_edid.bin"

kernel: [drm:drm_load_edid_firmware [drm_kms_helper]] *ERROR* Requesting EDID firmware "/usr/lib/firmware/edid/MacBookPro_11_2_edid.bin" failed (err=-2)

$ xvidtune -show
"2880x1800"   337.75   2880 2928 2960 3040   1800 1803 1809 1852 +hsync -vsync

$ ./modeline2edid - <<< 'Modeline "2880x1800"   337.75   2880 2928 2960 3040   1800 1803 1809 1852 +hsync -vsync'
$ make