The SGX graphics accelerator on the Beaglebone was always a debacle:
TI didn't opensource the drivers or even release proper documentation.
This apparently was due to the proprietary conditions they received
from the IP author, Imagination.
Apparently Imagination business model, instead of pure shrewdness,
turned out to be deeply flawed, and they seem to be on the ropes now:
http://www.eetimes.com/document.asp?doc_id=1328932&%3B_mc=NL_EET_EDT_EET_review_20160220&%3Bcid=NL_EET_EDT_EET_review_20160220&elqTrackId=d1a283ddfdd749989b48e29b1f0d368a&elq=a5703da753fe448e8e6cffa899d286fb&elqaid=30961&elqat=1&elqCampaignId=27068
I wonder if this would somehow help the case of open-source graphics driver...