I see/hear this structure rather frequently; (Verb) + ga ii. 来るがいい, 待つがいい, that kind of thing. However, I can't seem to find anything about it. JPod101 lessons are extremely confusing to search these days. -_-
The best I can make of this is that it's like "verb-te form + mo ii," except instead of being a question, it's an affirmation. たとえば, "来るがいい", "you can come." Am I on the right track here?
教えてください! m(-_-" )m