SoundWire For Linux Preps Support For Multiple Masters

Back in Linux 4.16 the SoundWire subsystem was added to the staging area as the MIPI standard for a low-power, two-wire sound bus that can support multiple audio streams and primarily utilized by small audio peripherals like IoT and mobile devices. With the next Linux kernel cycle, the SoundWire support is being improved upon.

The primary addition to SoundWire for the upcoming Linux 4.19 kernel cycle is the introduction of multi-link streaming. Up to now the Linux SoundWire code has just supported a single "master" and one or more "slaves" (codecs). With Linux 4.19, there is support for having multiple masters that share the same reference clock and synchronized in the hardware.

This multi-link support can be used for cases like left and right audio channels being rendered by different masters or other multiple audio channel scenarios.

This is among other work as part of this pull request for SoundWire in the kernel's staging area.