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Arm Cortex-A55 Core Technical Reference Manual : SIMD dynamic retention

SIMD dynamic retention

In this mode, the Advanced SIMD and floating-point logic is in retention (inoperable but with state retained) and the remainder of the core logic is operational.

This means that if an Advanced SIMD and floating-point instruction is executed while in this mode, it is stalled until the core enters the On mode.

When the Advanced SIMD and floating-point logic is in retention, the clock to the logic is automatically gated outside of the retained domain.

The SIMD dynamic retention is controlled by the CPUPWRCTLR.SIMD_RET_CTRL register.