UFS Storage Callback Response for Power State Management
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Solution Overview
Problem
In Universal Flash Storage (UFS) systems, there is a need for the storage device to send instructions to the host, as currently the host only instructs the storage device to perform tasks without the capability for the storage device to initiate commands.
Innovation Solution
The storage device sends a callback response containing a requested command triggered by an initial command from the host, allowing it to execute specific commands such as read or write buffer operations, and change power conditions, thereby enabling it to manage its own state transitions between active and sleep modes efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the host only instructs the storage device to perform tasks without the capability for the storage device to initiate commands, then the device complexity is reduced and ease of operation is improved, but the productivity and responsiveness of the storage device deteriorate
Solution Approach 1:
The patent applies inversion by enabling the slave storage device to send commands to the master host, reversing the traditional master-slave command initiation paradigm. The storage device can now initiate read buffer and write buffer commands autonomously based on its internal state and power conditions, rather than waiting for host initiation, thereby improving productivity while maintaining operational simplicity through automated decision-making
Solution Approach 2:
The storage device performs self-service by autonomously determining when to execute read or write buffer operations based on its power state and internal buffer conditions. The device self-manages its command initiation without requiring constant host intervention, improving responsiveness and productivity while the host maintains overall system control through the callback response mechanism
2Productivity
If the storage device sends a callback response containing a requested command, then the responsiveness and productivity are improved, but the device complexity increases
Solution Approach 1:
The patent implements feedback by having the storage device send callback responses to the host containing requested commands. The device monitors its own power state and buffer conditions, then provides feedback to the host through the callback mechanism, enabling autonomous decision-making while maintaining communication protocols that manage complexity through structured information exchange
Solution Approach 2:
The callback response mechanism serves multiple functions: it acknowledges host commands, reports storage device state, and initiates new commands. This multi-functionality improves productivity by consolidating communication operations into a single mechanism that handles both information exchange and command initiation, managing complexity through universal protocol design
3Loss of time
If the storage device autonomously manages power state transitions, then the time required to transition between active and sleep modes is reduced, but the ease of operation deteriorates
Solution Approach 1:
The storage device performs preliminary actions by proactively sending callback responses with requested commands before the host would naturally issue them. When transitioning from sleep to active state, the device pre-prepares and communicates buffer commands in advance, reducing transition time by eliminating waiting periods while the host maintains operational simplicity through the standardized callback interface
Data Source
AI summary
A method of sending a command from a slave storage device to a master host includes receiving an initial command from the master host. A callback response containing a requested command triggered by the initial command is sent by the slave storage device. In one embodiment, the master host is a Universal Flash Storage (UFS) host and the slave storage device is a UFS storage device. In one embodiment, the initial command is a start stop unit (SSU) command with a power condition field of sleep or powerdown and the requested command is a read buffer command. In another embodiment, the initial command is a start stop unit (SSU) command with a power condition field of active and the requested command is a write buffer command.


