Message Handling Unit for Power Domain Isolation
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Solution Overview
Problem
Implementing separate power domains in integrated circuits complicates the passing of messages between domains, as it requires a shared always-on message area to ensure message delivery, which increases power consumption and can lead to protocol breaks due to partial transactions during system resets.
Innovation Solution
A message handling unit that writes messages to a storage area within the second power domain and requests a wake-up for devices in a quiescent state, eliminating the need for a shared always-on domain by transitioning devices from a quiescent to an awake state only when necessary, thus avoiding the need for a permanent power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a shared always-on message area is provided to ensure message delivery between power domains, then message delivery reliability is improved, but power consumption increases and device complexity increases
Solution Approach 1:
The patent extracts the message storage function from a permanently powered shared domain and relocates it to the receiver domain's message storage area. This allows the message area to be powered down when not needed, eliminating the always-on power requirement while maintaining message delivery capability. The sender domain can still write messages by triggering a wake-up request to the receiver domain.
Solution Approach 2:
The patent implements dynamic power management where the receiver domain transitions from a quiescent state to an awake state only when a message send request is detected. This dynamic state change allows the system to consume power only when necessary for message processing, rather than maintaining a permanent powered state for message storage.
2Reliability
If a shared always-on message area is provided to ensure message delivery between power domains, then message delivery reliability is improved, but device complexity increases
Solution Approach 1:
The patent removes the need for a third shared always-on domain by extracting the message storage function to the receiver domain itself. This simplifies the system architecture by eliminating the intermediate shared domain while maintaining reliable message delivery through the wake-up request mechanism.
3Use of energy by stationary object
If separate power domains are implemented to save power, then power consumption is reduced, but message passing complexity increases
Solution Approach 1:
The patent implements a preliminary wake-up request action that is triggered when a message send request is detected. This preliminary action ensures the receiver domain is in the awake state before message writing begins, simplifying the message passing process by establishing a known good state rather than handling complex conditional logic during message transfer.
4Use of energy by stationary object
If devices transition from quiescent to awake state on message request, then power consumption is reduced, but message delivery time increases
Solution Approach 1:
The wake-up request is issued as a preliminary action immediately when a message send request is detected, before the actual message writing begins. This allows the receiver domain to start transitioning to the awake state in parallel with message preparation, minimizing the overall message delivery time while still achieving power savings during idle periods.
Data Source
AI summary
An integrated circuit comprises first and second power domains, and a message handling unit to control passing of messages sent from a sender device in the first power domain to a receiver device in the second power domain. The message handling unit writes messages sent from the sender device to a message storage area, provided in the second power domain. The message handling unit is responsive to a message send request from the sender device requesting sending of at least one message to the receiver device when at least one device in the second power domain is in a quiescent state, to transmit a wakeup request to a second domain power controller to request that said at least one device in the second power domain transitions from the quiescent state to an awake state.