I don't know any major GPU driver that can be shown to use any patent infringement. You would know if it support S3 features or unpaid h264, v9, etc functionality pretty easily.
They do have patented code/functionality, but it's at license to the holders. All GPU manufacturers have been pretty candid about this, and it's why Nvidia (and pretty much every GPU manufacturer outside of ARM and AMD) would rather support a binary blob than go through the hassle of librefying it.
