So there was one type of prime support, now there's another. And that means? What? That prime was broken before and is good now?
If I have got things right (which I seldom have) the thing here is that there are two ways of hooking up the hardware, and it comes down to which GPU is hooked up to the output (the physical connection to the screen), and which GPU could do the rendering, and "just output the image" through the chipset of the other GPU.
So PRIME is good if you computer has the intel gpu as primary, and allows the nvidia gpu to do rendering and output that trough the intel chips, while the reversed version is if your nvidia GPU is the "primary", hooked up one, but you want from time to time let the intel gpu do the rendering as it is less power hungry.
So without support for this, the first kind of hardware could never utilize the speed of the nvidia GPU since without PRIME it always used only the intel GPU, while the latter hardware was always draining power as the nvidia GPU is more hungry, and the driver could not let it step aside and let the intel GPU do the work.
At the end he mentions what reverse prime is. I think it was basically the case where the nvidia card has a displayport (or other) output and when you connect a monitor you want the nvidia card doing the rendering and the outputting stuff while the intel chip is only used to display stuff the nvidia card renders on LVDS.
I have (almost) no clue about Optimus and the Linux graphics stack. But I am wondering if this reverse PRIME support will enable the HDMI output on my Lenovo E530 Thinkpad. It has a VGA output which works (connected to Intel HD4000), but afaik the HDMI output is directly connected to the Nvidia Optimus graphic card and did not work so far.
Will reverse PRIME support bring us closer (how close?) to a plug'n'play HDMI output? Or has this nothing to do with each other?