Lots Of X.Org GLAMOR Improvements Planned
Eric Anholt presented this past week at Linux.Conf.Au 2014 about his recent GLAMOR work, which can be watched via this mirror (MP4 file). GLAMOR is the implementation of X.Org 2D code-paths implemented using OpenGL shaders. GLAMOR continues to be offered as a build-time option for the Intel DDX while it's required within the AMD Radeon driver for 2D acceleration on Radeon HD 7000 series graphics processors and newer.
The benefit to GLAMOR is that around 200,000 lines of device dependent code could be replaced by a few thousand lines of device independent code. Besides having device-dependent 2D-focused code being a huge maintenance burden, it's an ever-growing burden with new code being needed for each driver and each new graphics hardware generation. The huge work involved is part of the reason why AMD has already committed to GLAMOR for all new hardware.
The downside though to using GLAMOR right now is slower performance than having dedicated 2D DDX code-paths. There's also higher CPU overhead in using 2D with OpenGL. On the performance front, Eric has been making some improvements in his various branched code-bases, but much work is left ahead.
Some of the upcoming items left to be accomplished in the GLAMOR world include finishing DRI2/DRI3 page-flipping for the generic DDX mode-setting driver, fixing the DRI3 API for PRIME support, adding X-Video overlay support, finishing OpenGL ES 2.0 support, porting GLAMOR to core OpenGL, and making it all an automatic page-flipping no-tearing X compositor experience.
Those wishing to learn more on the current and future work should watch Eric's presentation from the aforementioned link. There's also many other Phoronix articles on GLAMOR.