Indeed, and it continues to be a problem on 4.16. I'm guessing something about moving from drm_kms_firmware.edid_firmware to drm.edid_firmware broke this. Maybe this should be reported upstream?
- Bug#894731: linux-image-4.15.0-2-amd64: Setting d... Henrik Friedrichsen
- Bug#894731: linux-image-4.15.0-2-amd64: Sett... Ricardo MartÃn Camarero
- Bug#894731: linux-image-4.15.0-2-amd64: Sett... Andreas Schreiner
- Bug#894731: linux-image-4.15.0-2-amd64: Sett... Henrik Friedrichsen
- Bug#894731: linux-image-4.15.0-2-amd64: Sett... Henrik Friedrichsen
- Bug#894731: linux-image-4.15.0-2-amd64: Sett... Ricardo Martin Camarero