iPhone X chip shows problems of Imagination

September 15, 2017 // By Nick Flaherty
The launch of the latest Apple iPhones has raised some interesting questions on the IP used in the chips.

The A11 Bionic applications processor in the iPhone 8 and iPhone X uses an entirely new graphics processor sub-system, says Apple. This is made up of three ‘all new’ cores.

This points to a collapse in the relationship between Apple and Imagination Technology much earlier than previously thought.

The GPU in the iPhone 7 uses a custom version of the PowerVR GT7600 GPU, which had some disappointing benchmarks, but even in early 2017 Imagination was looking to replace that with a GPU design using its Furian architecture.

A new GPU sub-system would take at least 18 months to design and verify as part of the overall chip design on the latest 10nmm process so it is very lear that Apple has spent at least two years developing a new technology. This meant the architecture specification was being decided long before the public fallout of the two companies and would be consistent with Apple telling Imagination in late 2015.

Imagination is not saying much, except that “our position – which is that we don’t see how they are making a GPU that doesn’t use our technology – remains the same,” said a spokesperson.

The central processing blocks appear to be a custom version of ARM’s Dynamiq architecture that was launched earlier this year. There are two ‘performance’ cores, codenamed Monsoon, which would correlate to the ARM Cortex-A75, and four ‘efficiency’ cores, called Mistral, that are similar to the A55. These are controlled by a performance and power scaling block, which was the new addition with Dynamiq. In ARM version, this block also handles the interface to the GPU cores, as well as to any accelerators for machine learning or AR, which have been hinted at. There is a dedicated block for handling CNN

This leads to the question whether custom versions of ARM’s Mali graphics core has been used, or whether this is an entirely new graphics architecture, which wuld ahve taken even longer to develop, implement and verify.