We already wrote about Mediatek's 20nm Helio X20 SoC, which features three core clusters including low power cluster based on four Cortex-A53 cores clocked at 1.4GHz, medium performance cluster based on four Cortex-A53 cores clocked at 2.0GHz and high performance cluster with two Cortex-A72 cores clocked at up to 2.5GHz. All three clusters share their own L2 cache and all clusters can run together when necessery and dinamically change clocks when necessery.
While it is all about power efficiency and, of course, performance when needed, with the new deca-core approach on the Helio X20 SoC, Mediatek also decided to incorporate a Cortex-M4 companion core. Mediatek claims that this is world's first SoC with integrated Cortex-M4, which should act as both an audio processor as well as for sensor data processing.
The Cortex-M4 companion core is clocked at up to 364MHz, has dedicated 512KB of SRAM, has direct access to DRAM and should take care of any sensor data processing and also act as an audio processor that will take care of low-power audio decoding, speech enhancement features, voice recognition and is even able to play MP3s without turning on any of the aforementioned ten CPU cores.
The Cortex-M4 should significantly improve battery life as we guess that this chip use less power than any of those core clusters and should allow the rest of those core clusters to remain disabled in most low-power tasks.
Of course, we are still far away from an actual device based on Mediatek's Helio X20 SoC as samples are expected in Q3 2015 and actual products should come early next year.