Pandora 2 could switch to Broadcom and get open-source 3D drivers

[larry]

Broadcom just open-sourced the 3D driver used for the part in the Raspberry Pi:


http://www.raspberrypi.org/archives/2221


Obviously an open-source driver is highly desirable for Pandora 2. Clearly P2 wouldn't use the same hardware as in the Raspberry Pi. But perhaps by then the writing will be on the wall and Broadcom will open-source all their 3D drivers.

 

[Binky]

You know, using the same hardware as the Rpi could be a really good move, as you get free:

• marketing hype
  
• heaps of software
  
• noticed by another positive nerdy crowd
  

An RPi model B in a pandora body would by awesome

 

[ShleeDragon]

The Raspi SOC is old hat.. considering it's the GPU userland stuff... that would be awesome if it's supported by newer releases.

 

[_wb_]

Something that is backwards compatible to the Rpi would be nice, but not essential.


Having open source drivers/firmware for as much of the hardware as possible would certainly be a good thing.

 

[Binky]

Maybe an RPi SOC could be available through Craig's modular system

 

[wermy]

Maybe someone like Exophase would care to chime in here: how does the RPi GPU compare to the Pandora's?

 

[notaz]

Using the same SoC would be crazy, it's slower than what's on pandora1 and it doesn't even have NEON. I haven't looked at that driver codedrop, but I would be surprised if it supported anything but RPi's chip.

 

[Binky]

null

 

[Exophase]

Maybe someone like Exophase would care to chime in here: how does the RPi GPU compare to the Pandora's?

Broadcom hasn't said that much about how it works, and those details are probably still hidden under blobs that run on the GPU itself. One of the RPi people said it'd outperform Tegra 3's GPU before Tegra 3 devices were even out. From what I've heard it sounds like it has code running on specialized DSPs. Broadcom claims 1 gigapixel/s fill rate, which is far beyond the true fill rate of Pandora (110 megapixel/s or 200 for the 1GHz models)


It appears to be using some kind of specialized vector floating point DSP. It has been RE'd a bit here: https://github.com/h...grammers-Manual


There's a big 64x64x8bit vector matrix available for 16-wide operations. I would guess they're doing tiled rendering directly to this matrix. I don't know anything about what resources it has for texturing; it surely has to have some dedicated TMUs and probably dedicated rasterizers to get good performance.

 

[hns]

Well, view RasPI more or less as a copy of a BeagleBoard - by swapping the OMAP3 from Texas Instruments (the same as in OpenPandora and e.g. GTA04) with something else. Of course it comes with a different GPU - but is anything better with it?


And there is also a FSF project to write a free and open replacement driver for the PowerVR GPUs used in the OpenPandora and many other devices (e.g. iPhone 5):


http://powervr.gnu.o...ku.php?id=start


I find it is a better strategy to support this project as good as we can rather than switching to a different GPU.

 

[Pickle]

The driver drop is less appealing than what is being marketed. The real driver code is running on the VideoCore GPU which is not open. Anaylsis so far reveals that what was released boils down to being a software shim. The VideoCore API is closely designed around the OpenGL API so that the shim justs passes the data to the gpu.


So really its a slight of hand to claim the driver is completly being opensourced.


I agree with the above opinions this would not be a great choice for pandora in the future. The performance is lacking. Of course it makes sense for the RPi project as it isnt meant to be cutting edge but cost effective.

 

[Exophase]

I guess people are used to more low level GPUs (ie almost all of them) that don't have OpenGL drivers running on-chip.

 

[larry]

What Pickle said.


http://airlied.livejournal.com/76383.html

 

[Exophase]

There's been some anger over this from the FSF faithful, but the fact is this is still pretty useful because it means the drivers can be ported to other operating systems and still work. Chalk it up to Broadcom's unusual architecture more than any willingness to be more open than the others, but it's still an advantage.


Some people are just never going to appreciate anything that isn't 100% what they want...