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   Computer Nerd Kev  wrote:   
   > bp@www.zefox.net wrote:   
   >> Computer Nerd Kev  wrote:   
   >>> No the code running on the GPU is all written by Broadcom and Linux   
   >>> software just talks to that, so nothing needs to be compiled for   
   >>> the GPU in order to use functionality that's in the stock GPU   
   >>> firmware. The bottleneck at this point seems to be mainly   
   >>> application developers adding support for the APIs, but this isn't   
   >>> an issue with compilers, just the usual limits of time, money, and   
   >>> willpower.   
   >>   
   >> Ok, that clarifies things considerably. Is the API public, at least?   
   >> Then folks could experiment.   
   >   
   > Broadcom's API is DispmanX, which some programs have used directly,   
   > but libbrcmEGL is their library that presents an OpenGL interface   
   > and is thus easier to adapt software to. Separately the Linux   
   > kernel now has its own drivers, which are used via Mesa. I'm not   
   > sure how the performance compares, but the Mesa drivers are the   
   > popular ones these days.   
      
   At the risk of correcting myself about details that nobody cares   
   about anyway, it turns out the original work on Mesa's VC4 driver   
   was led by a Broadcom developer as well. So that would really be   
   Broadcom's current graphics API. Seems it actually bypasses the   
   original closed-source firmware running on the VPU, to do that   
   graphics processing on the CPU instead, which is a bit of a waste   
   of the GPU's processing abilities. But it seems they preferred that   
   to opening the sources and build system for the VPU firmware and   
   improving upon that, though that's still used for hardware   
   management tasks.   
      
   Here's the VC4 driver developer's blog:   
   https://anholt.livejournal.com/   
      
   And their post about being hired by Broadcom to write the GPU   
   driver for Mesa and the Linux kernel:   
   https://anholt.livejournal.com/44239.html   
      
   More recently the GPU drivers for the RPi4 and 5 have be developed   
   by Igalia, presumably as sub-contractor for Broadcom since Igalia   
   took over from the Broadcom developer:   
   https://www.raspberrypi.com/news/vc4-and-v3d-opengl-drivers-for-   
   aspberry-pi-an-update/   
   https://www.igalia.com/2023/09/28/Raspberry-Pi-5-Announced.html   
   https://www.igalia.com/technology/graphics   
      
   It's interesting to find out where all this code comes from.   
   Broadcom have been more involved than I thought.   
      
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