OpenGL 2.x support

This might be a long shot - more a question than a bug - but how much work would it take to be able to advertise GL 2.x support? I have no idea how many of the extensions missing from OpenGL ES 2 are needed for GL 2, let alone what it'll take to implement them, but from what little I've read - specifically about the Intel GMA950 drivers going from only supporting GL 1.5 to 2.1 - coding support for occlusion queries might make this possible.

Just a hunch from a quick review of the code. I wish I understood half of it...

[robclark]

adreno a2xx lacks integer support for shaders, so it would never be able to support enough for gl2 glsl.. a3xx does support integers so that should be possible, although I'm not entirely sure about occlusion query.. that does seem to be supported in gles3 and the hw is gles3 capable but I don't have gles3 drivers yet to see how that works. I'm not sure if there might be something else missing for full gl2 support.

I'm going to assume there's no point doing a float<->int conversion hack (if such a thing is possible) for a2xx since that type of thing is usually very expensive... As for the other features, I guess I'll find out when I tell the driver to lie about its capabilities :P

[robclark]

the problem is no bitwise operations, so float<->int conversion isn't sufficient.

You can lie about the caps, it will work up until the point where a shader triggers use of some TGSI instructions that can't be supported. But I ran into a problem w/ some intrinsics compiling into things I can't support without int if I advertise a higher GLSL version.

Well I managed to get glxinfo to report OpenGL 2.1 by adding stub occlusion query support (pretty much copying from the i915 drivers). It should surprise no one that glxgears rendered crescents instead of gears at under 15FPS.
I think I satisfied my curiosity :P

[freedreno-zz]

hmm, at least for GL1.4, glxgears needed TGSI_OPCODE_LIT, which I hadn't implemented yet (although es2gears which uses glsl shaders works ok). 15fps seems like it might be software fallback? For es2gears, on HP touchpad, iirc it was around ~100+ fps, nexus4 (a320) is somewhat faster at ~400fps. And I'm sure in both cases there is lots of room for optimization.

I'm pretty sure it's running freedreno and not swrast (OpenGL vendor: freedreno, OpenGL render string: Gallium 0.4 on FD001)... Either way, it seems to be doing most of the work on the CPU, so there's definitely a software fallback happening somewhere.

[freedreno-zz]

fwiw, here are the configure flags that I use:

./autogen.sh --prefix=/usr --with-dri-drivers= --with-gallium-drivers=freedreno,swrast --with-egl-platforms=x11 --enable-gles2 --enable-gles1 --enable-debug --enable-gallium-egl --disable-gallium-llvm --enable-xa

My only significant deviation from those flags is I don't think I enabled xa. It probably won't make much of a difference. Real occlusion queries would be nice, but I figured there's no harm in sharing dumb little hacks like this. I sorted out the segfault, and I thought I'd mention es2gears runs at 60fps in near-fullscreen on my TouchPad. I'm crossing my fingers for the rumored Snapdragon Nexus 7...

Yeah, unless you want my stub occlusion query hack (unlikely since you could probably implement it for real in less time than it took me), and/or have another use for my limited skills, you may close this ticket, being that it was more of a feature request than a bug report,

[freedreno-zz]

fwiw, the a3xx should support occlusion query, and I suspect the a2xx does as well. But, as far as I can tell the gles2 blob drivers do not implement any occlusion related extension, and I think we only get gles3 on a3xx. So at least for the newer devices, I think we should eventually be able to do this in hw. But I don't have gles3 blob drivers on my nexus4, and I cannot download the latest drivers from qcom without a EULA, so I haven't been able to look into how this works yet.

Anyways, if you have a patch, feel free to post it, or even just send to mesa-devel (whichever you prefer) and I will review it.