Here's some interesting content about the MIPI SPMI specification:
MIPI SPMI is optimized for high-speed, low-latency communication: Speed Classifications Low Speed (LS) : 32 kHz to 15 MHz. High Speed (HS) : 32 kHz to 26 MHz. Bus Arbitration Round Robin mipi spmi specification pdf
Full members can download the complete, "adoption-ready" PDF directly from the MIPI Alliance website. Here's some interesting content about the MIPI SPMI