Apple Plans to Develop a Fully Custom GPU Architecture
Apple will develop its own custom graphics architecture to power the GPUs for its future devices, according to UK-based firm Imagination Technologies, Apple’s current GPU provider. The new GPUs should be ready in 15 months to two years time and will be the first Apple-made GPUs that will bear no resemblance to Imagination Technologies’.
This is how Imagination Technologies have announced Apple’s decision, which would have been otherwise remained undisclosed, given the known secretiveness of the company:
[Apple] has been working on a separate, independent graphics design in order to control its products and will be reducing its future reliance on Imagination’s technology.
In fact, speculation about Apple aiming to develop its own GPU architecture was widespread in the industry, since Apple has been known to poach Imagination Technologies’ and other companies’ graphics hardware engineers since at least October 2016. And indeed, according to Real World Technologies’ David Kanter, a first Apple-own GPU design made its debut on the iPhone 7 last year, although that was speculatively only partially original and mostly based on the pre-existing design from Imagination Technologies. Among the differences between Apple's and Image Technologies’ designs that were identified by Kanter, are the GPU register file organization and data conversion pipeline.
Now, based on Imagination Technologies disclosure, it seems that Apple is working towards a completely new architecture that "will no longer require Imagination's technology, without violating Imagination's patents, intellectual property and confidential information". It is not known in which direction Apple will drive the evolution of its current GPU design, though Benedict Evans suggests that:
Apple is pushing into ‘computational photography’ with the iPhone 7+ camera, GPUs are central to running machine learning locally […], and, further out, Apple is (probably) working on augmented reality glasses, which will need to do all sorts of computer vision and image processing to work well.
The move towards a fully custom architecture for the GPU resembles the decision to start creating a fully proprietary architecture for the CPU which led to the A4 design in 2010, and which continued to the latest A10 design that powers the iPhone 7. Apple’s CPU architecture, being extremely optimized for use on handheld devices, is considered to be one of the most important factors behind Apple’s performance advantage over competitors.
Imagination Technologies has powered the iPhone GPU stack from its introduction with its PowerVR architecture, specifically aimed to OpenGL ES, OpenVG, and OpenCL acceleration. Among its distinctive features, PowerVR enabled the creation of low-power system-on-a-chip implementations that were suitable for use in handheld devices such as Apple’s, including the iPhone, the iPad, the Apple Watch, and the Apple TV. The adoption of a dedicated GPU natively supporting 2D and 3D animations is considered a key factor that made iOS responsive even on rather under-powered hardware such as that used with the original iPhone.