Many are familiar with ARM and its CPUs and GPUs. They are found in billions of devices around the world and help to power some of the fastest SoCs inside today’s leading smartphones. However, ARM also makes a whole host of other processors, including neural processing units (NPUs) for AI and display processing units (DPUs) for displays. ARM’s DPUs are usually paired with the company’s GPUs to allow for the optimal user experience in terms of battery life and responsiveness. This is important for devices like smartphones and tablets, where the display is the primary means of interfacing with the phone. Now ARM has introduced a new display processor that caters specifically to the VR market—the Mali D77.
A closer look
Naturally, as designs and use cases start to solidify, so do the types of processing that occurs. Now that VR has matured to a certain degree, ARM has decided it can build some common VR workloads into hardware on its display processors. This move is important because moving these workloads from the GPU to the display processor helps to save on latency, power, and performance.
The ARM Mali D77 is geared towards head-mounted displays inside of VR headsets. If you look at the mobile VR market today, it is moving away from slot-in smartphone-based VR solutions and towards standalone VR solutions like the HTC Vive Focus, Oculus Quest, and Lenovo Mirage Solo. These fully integrated headsets combine both the display and the processing into one device, which elevates the user experience in terms of performance, comfort, and battery life. The next natural step of integration is to continue to optimize these designs for even more performance and battery life. The D77 is a big move in that direction because it integrates functions like lens distortion correction (LDC), chromatic aberration correction (CAC), and asynchronous timewarp (ATW) into the display processor, rather than doing them on the GPU. All three of these workloads are extremely common in VR headsets and considered to be base-level features.
By integrating these fundamental VR workloads, ARM claims to reduce bandwidth by 40%. This translates to more bandwidth for processing other things. ARM also claims power savings of 12%, which frees up the GPU to do more graphics processing. This could translate to higher quality visuals or higher framerates. The D77, when paired with ARM’s MMU-600 and Assertive Display 5 processors, is capable of driving displays at 3K resolution at 120 fps or 4K at 90 fps. Because the D77 DPU is doing so many of the common VR workloads, the GPU is freed up by about 15%--a considerable amount of extra available performance. ARM is even working with industry leaders like Synaptics to enable its ultra-high-resolution VR microdisplays and ensure that there is a display processor capable of running those resolutions at the necessary frame rates to maintain a quality user experience.
Ultimately, I believe the D77 is a very focused new product from ARM that will meaningfully change the VR industry. I think we will probably see devices with the D77 starting in mid-to-late 2020—the D77 still needs to find its way into the ARM customer chip design, which then needs to be manufactured and integrated into a VR headset design. While companies like Pico are already integrating 4K displays into their standalone VR headsets, the D77 should help to enable higher resolutions at lower price points. This is ultimately what the market needs in order to continue to mature, and I am excited to see it all take shape, especially with much-awaited devices like the Oculus Quest launching this month.