Raspberry Pi VC4 Graphics Driver Working To Support QPU Shaders
Written by Michael Larabel in Hardware on 12 October 2016 at 09:28 AM EDT. Add A Comment
HARDWARE --
The latest Raspberry Pi graphics driver hacking by Eric Anholt of Broadcom has been working to support QPU shaders by this open-source driver stack. QPUs are the shader core of the graphics hardware found in the Raspberry Pi SoC, but come up short of supporting OpenCL or OpenGL compute shaders.

QPU shaders aren't suitable enough for handling OpenGL compute shaders or OpenCL for GPGPU, but does allow writing QPU shaders in raw assembly for execution on these shader cores. Anholt hasn't been working on supporting QPU shaders via the open-source VC4 driver stack due to these limitations plus there are security implications too since the lack of an MMU allows the GPU shader programs to access anywhere in system memory.

Eric is looking at supporting QPU shaders now though with this open-source driver stack since it can be used for accelerated video decode. For now he's pursuing an approach where there is root-only execution of the QPU shaders due to lack of validation support. He's got an experimental implementation currently running in his kernel tree and is looking like this support might come to the VC4 DRM driver with the Linux 4.10 kernel.

Those interested in more information can read this blog post.

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Michael Larabel is the principal author of Phoronix.com and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 10,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and OpenBenchmarking.org automated benchmarking software. He can be followed via Twitter or contacted via MichaelLarabel.com.

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