Looks up the spec to see the correct behavior, just ask the person did the change, or test it yourself to see why is there a contrasting comment. May be hardware acceleration was meant to be turned off but the guy was testing it by toggling the flag and forgot to set it back. In that case the conflicting comment brings the potential bug upfront.

Find out who the author was via git blame and ask what they were thinking when writing it. Or in the case that the person who wrote it left, contact someone with some knowledge of the line in question (i.e. the person who either also wrote the majority of the code or is at least familiar with what it does) and ask. If it comes down to it and you're the only one qualified to do something about it, then just remove the line (assuming the code is functioning properly) just how I would approach it.