# US 2023/0273669 A1 · Hierarchical power management in artificial reality systems > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2023/0273669 A1 - Document ID: US20230273669A1 - Status: Published application - Kind: A1 - Application number: 18/312,404 - Filed: 2023-05-04 - Published: 2023-08-31 - Earliest claimed: 2019-11-22 - Assignees: Meta Platforms Technologies, LLC - Applicants: Meta Platforms Technologies, LLC - Inventors: Shrirang Madhav Yardi; Alok Kumar Mathur - Web page: https://patentgrep.com/patent/US20230273669A1 ## CPC - G06F 1/3287: by switching off individual functional units in the computer system - G06F 1/3206: Monitoring of events, devices or parameters that trigger a change in power modality - G06F 1/325: {Power saving in peripheral device} - G06F 3/011: {Arrangements for interaction with the human body, e.g. for user immersion in virtual reality (blind teaching G09B21/00)} - G06F 3/013: {Eye tracking input arrangements (G06F3/015 takes precedence)} - G06F 3/014: {Hand-worn input/output arrangements, e.g. data gloves} - G06F 3/017: {Gesture based interaction, e.g. based on a set of recognized hand gestures (interaction based on gestures traced on a digitiser G06F3/04883)} - Y02D 10/00: Energy efficient computing, e.g. low power processors, power management or thermal management - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - Y02D: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE ## Abstract The disclosure describes artificial reality (AR) systems and techniques that enable hierarchical power management of multiple devices within a multi-device AR system. For example, a multi-device AR system includes a device comprising one of a peripheral device configured to generate artificial reality content for display or a head-mounted display unit (HMD) configured to output artificial reality content. The device comprises a System on a Chip (SoC) that includes a host subsystem and plurality of subsystems. Each subsystem includes a child energy processing unit configured to manage power states for the subsystem. The host subsystem includes a parent energy processing unit configured to direct power management of each of the child energy processing units of the plurality of subsystems. ## Claims ### Claim 1 An artificial reality system comprising: a device comprising one of a peripheral device configured to generate artificial reality content for display or a head-mounted display unit (HMD) configured to output artificial reality content, wherein the device comprises a host subsystem and a plurality of non-host subsystems, wherein each non-host subsystem of the plurality of non-host subsystems includes a local processor and a child energy processing unit (EPU) connected to the local processor, and wherein the host subsystem comprises a parent EPU and is configured to: determine and indicate a non-host subsystem of the plurality of non-host subsystems is to be powered up, in response to a determination a corresponding power domain of the determined non-host subsystem is awake, generate a reset vector and release, and send the generated reset vector and release to the corresponding non-host subsystem to cause the local processor of the non-host subsystem to initiate a cold boot sequence. ### Claim 2 (depends on 1) The artificial reality system of claim 1, wherein the host subsystem further includes a control and status register, and the parent EPU of the host subsystem is configured to write values to the control and status register indicative of the non-host subsystem to be powered up. ### Claim 3 (depends on 1) The artificial reality system of claim 1, wherein each of the non-host subsystems are split into a plurality of power domains. ### Claim 4 (depends on 3) The artificial reality system of claim 3, wherein in response to the determination the non-host subsystem of the plurality of non-host subsystems is to be powered up, the parent EPU is configured to turn on a first power domain of the non-host subsystem to power up the child EPU of the non-host subsystem. ### Claim 5 (depends on 4) The artificial reality system of claim 4, wherein the host subsystem further includes a top-level clock, wherein the child EPU of the non-host subsystem is configured to request a default clock from the top-level clock of the host subsystem, and the top-level clock of the host subsystem is configured to send a clock acknowledgement to the child EPU in response to receiving the request for the default clock. ### Claim 6 (depends on 5) The artificial reality system of claim 5, wherein the child EPU of the non-host subsystem is further configured to turn on a second power domain of the non-host subsystem in response to receiving the clock acknowledgement. ### Claim 7 (depends on 6) The artificial reality system of claim 6, wherein to determine the corresponding power domain of the determined non-host subsystems is awake, the host subsystem is further configured to determine the second power domain of the non-host subsystem is awake. ### Claim 8 (depends on 6) The artificial reality system of claim 6, wherein the host subsystem is further configured to: read a power status of a local processor of the child EPU; and determine the second power domain is ungated based on reading the power status of the local processor of the child EPU. ### Claim 9 (depends on 1) The artificial reality system of claim 1, wherein the local processor of the non-host subsystem is configured to: hold in a reset; and in response to receiving the generated reset vector and release, initiate the cold boot sequence. ### Claim 10 A method comprising: determining and indicating, by a host subsystem of an artificial reality system, a non-host subsystem of a plurality of non-host subsystems is to be powered up; in response to a determination a corresponding power domain of the determined non-host subsystems is awake, generating, by the host subsystem, a reset vector and release; and sending, by the host subsystem, the generated reset vector and release to the corresponding non-host subsystem to cause a local processor of the non-host subsystem to initiate a cold boot sequence. ### Claim 11 (depends on 10) The method of claim 10, wherein determining and indicating, by the host subsystem, the non-host subsystem of the plurality of non-host subsystems is to be powered up further includes writing values to a control and status register, of the host subsystem, indicative of the non-host subsystem to be powered up. ### Claim 12 (depends on 10) The method of claim 10, wherein each of the non-host subsystems are split into a plurality of power domains. ### Claim 13 (depends on 12) The method of claim 12, further comprising: in response to the determination the non-host subsystem of the plurality of non-host subsystems is to be powered up, turning on, by parent energy processing unit (EPU) of the host subsystem, a first power domain of the non-host subsystem to power up a child EPU of the non-host subsystem. ### Claim 14 (depends on 13) The method of claim 13, further comprising: requesting, by the child EPU, a default clock from a top-level clock of the host subsystem; and sending, by the top-level clock of the host subsystem, a clock acknowledgement to the child EPU. ### Claim 15 (depends on 14) The method of claim 14, further comprising: in response to receiving the clock acknowledgement, turning on, by the child EPU of the non-host subsystem, a second power domain of the non-host subsystem. ### Claim 16 (depends on 15) The method of claim 15, further comprising: determining the second power domain of the non-host subsystem is awake to determine the corresponding power domain of the determined non-host subsystems is awake. ### Claim 17 (depends on 15) The method of claim 15, further comprising: reading, by the host subsystem, a power status of a local processor of the child EPU; and determining, by the host subsystem, the second power domain is ungated based on reading the power status of the local processor of the child EPU. ### Claim 18 (depends on 10) The method of claim 10, further comprising: in response to receiving the generated reset vector and release, initiating, by the local processor of the child EPU, the cold boot sequence. ### Claim 19 (depends on 10) The method of claim 10, wherein the artificial reality system comprises one of a peripheral device configured to generate artificial reality content for display or a head-mounted display unit (HMD) configured to output artificial reality content. ### Claim 20 A non-transitory computer-readable storage medium comprising instructions that, when executed, configure processing circuitry of an artificial reality system to: determine and indicate, by a host subsystem of the artificial reality system, a non-host subsystem of a plurality of non-host subsystems of the artificial reality system is to be powered up; in response to a determination a corresponding power domain of the determined non-host subsystems is awake, generate, by the host subsystem, a reset vector and release; and send, by the host subsystem, the generated reset vector and release to the corresponding non-host subsystem to cause a local processor of the non-host subsystem to initiate a cold boot sequence.