On Mon, Nov 26, 2012 at 5:32 PM, Thierry Reding <thierry.reding@xxxxxxxxxxxxxxxxx> wrote: > On Sun, Nov 25, 2012 at 09:51:46PM -0500, Alex Deucher wrote: >> On Sat, Nov 24, 2012 at 4:09 PM, Thierry Reding >> <thierry.reding@xxxxxxxxxxxxxxxxx> wrote: >> > going into Linux 3.8 and NVIDIA posting initial patches >> > for 2D acceleration on top of it, I've been looking at the various ways >> > how this can best be leveraged. >> > >> > The most obvious choice would be to start work on an xf86-video-tegra >> > driver that uses the code currently in the works to implement the EXA >> > callbacks that allow some of the rendering to be offloaded to the GPU. >> > The way I would go about this is to fork xf86-video-modesetting, do some >> > rebranding and add the various bits required to offload rendering. >> > >> > However, that has all the usual drawbacks of a fork so I thought maybe >> > it would be better to write some code to xf86-video-modesetting to add >> > GPU-specific acceleration on top. Such code could be leveraged by other >> > drivers as well and all of them could share a common base for the >> > functionality provided through the standard DRM IOCTLs. >> > >> > That approach has some disadvantages of its own, like the potential >> > bloat if many GPUs do the same. It would also be a bit of a step back >> > to the old monolithic days of X. >> >> Just fork and fill in your own GPU specific bits. Most accel stuff >> ends up being very GPU specific. > > That doesn't exclude the alternative that I described. Maybe I didn't > express what I had in mind very clearly. What I propose is to add some > code to the modesetting driver that would allow GPU-specific code to be > called if matching hardware is detected (perhaps as stupidly as looking > at the DRM driver name/version). Such code could perhaps be called from > the DDX' .ScreenInit and call the GPU-specific function to register an > EXA driver. > > That would allow a large body of code (modesetting, VT switching, ...) > to be shared among a number of drivers instead of duplicating the code > for each one and having to keep merging updates from the modesetting > driver as it evolves. So the GPU-specific acceleration would just sit on > top of the existing code and only be activated on specific hardware. > What I'm *not* proposing is to create an abstraction layer for > acceleration. > vmware kinda did something like that initially with modesetting, it was a bit messier, it would be nice though to just plug in stuff like glamor and things, but you still need to deal with pixmap allocation on a per-gpu basis. I'd rather make the modesetting code into a library, either separate or in the X server, but i've also investigated that and found it was too much effort for me at the time also. Dave. -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
