the old drm code for i915 is probably extremely obsolete at this point. i don't think it works on anything that current does (or least, before the latest refresh -- i think there are still a couple of blank screens, but i think newer than this code would support anyway.)
the only reason i haven't removed it all is that for old radeon (R100/R200), some systems can't use new drm and you end up with both a black-on-black (or similarly unusable) console setup, and X doesn't work anyway. there's some problem with LUT setup in the current code, but there are no public docs and no one with access to them cares. removing from configs is probably a decent idea at this point. kre, this drm hasn't been the "main" drm since july 2013, we've had linux 3.8, 4.4, and now 5.6 based drm (all have the same failure mode.) .mrg.
