# US 10,482,056 B2 · Transfer of master duties to a slave on a communication bus

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- Number: US 10,482,056 B2
- Document ID: US10482056B2
- Status: Granted
- Kind: B2
- Application number: 15/819,641
- Filed: 2017-11-21
- Published: 2019-05-23
- Granted: 2019-11-19
- Earliest claimed: 2017-11-21
- Assignees: QUALCOMM Incorporated
- Applicants: QUALCOMM Incorporated
- Inventors: Lior Amarilio; Yuval Corey Hershko; Nir Strauss
- Web page: https://patentgrep.com/patent/US10482056B2

## CPC

- G06F 13/4291: {using a clocked protocol}
- G06F 13/362: with centralised access control
- G06F 13/364: using independent requests or grants, e.g. using separated request and grant lines
- G06F 15/7807: {System on chip, i.e. computer system on a single chip; System in package, i.e. computer system on one or more chips in a single package}
- G06F 1/3287: by switching off individual functional units in the computer system
- 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

Systems and methods to transfer master duties to a slave on a communication bus are disclosed. A master of a communication bus determines that one or more slaves are capable of serving as a sub-master, including providing a clock signal and owning control information bits. Once that determination is made, the master may determine that processing within the master is not required for a particular activity on the bus. The master then alerts one such capable slave to prepare to assume sub-master duties. Once the slave confirms that the slave is ready to assume the sub-master duties, the master may transmit a handover frame on the bus, and the slave begins acting as a sub-master. The master may then enter a low-power state, which may promote power savings, reduce heat generation, and provide other advantages.

## Claims

### Claim 1

A master integrated circuit (IC) on a SOUNDWIRE bus comprising:
a bus interface configured to be coupled to the SOUNDWIRE bus;
a transceiver coupled to the bus interface; and
a control system operatively coupled to the transceiver and configured to:
instruct a slave device amongst a plurality of slave devices coupled to the SOUNDWIRE bus to prepare to assume sub-master control of the SOUNDWIRE bus; and
pass master duties to the slave device by sending a handover command across the SOUNDWIRE bus and sending a handover frame to mark passed control.

### Claim 2 (depends on 1)

The master IC of claim 1, wherein the control system is further configured to determine that the slave device is capable of assuming a sub-master role.

### Claim 3 (depends on 2)

The master IC of claim 2, wherein the control system configured to determine that the slave device is capable of assuming the sub-master role comprises the control system configured to read capabilities from the slave device.

### Claim 4 (depends on 3)

The master IC of claim 3, wherein the control system configured to read the capabilities from the slave device comprises the control system configured to read the capabilities from either a register or a discoverable (DISCO) file.

### Claim 5 (depends on 2)

The master IC of claim 2, wherein the control system configured to determine that the slave device is capable of assuming the sub-master role comprises the control system configured to receive information from an external source.

### Claim 6 (depends on 5)

The master IC of claim 5, wherein the control system configured to receive the information from the external source comprises the control system configured to receive the information from an application processor, a digital signal processor, or an operating system.

### Claim 7 (depends on 1)

The master IC of claim 1, wherein the control system is further configured to abort handover of the master duties before passing the master duties to the slave device.

### Claim 8 (depends on 1)

The master IC of claim 1, wherein the control system is further configured to receive information from the slave device indicating readiness to assume the sub-master control of the SOUNDWIRE bus.

### Claim 9 (depends on 1)

The master IC of claim 1 integrated into a device selected from the group consisting of: a set top box; an entertainment unit; a navigation device; a communications device; a fixed location data unit; a mobile location data unit; a global positioning system (GPS) device; a mobile phone; a cellular phone; a smart phone; a session initiation protocol (SIP) phone; a tablet; a phablet; a server; a computer; a portable computer; a mobile computing device; a wearable computing device; a desktop computer; a personal digital assistant (PDA); a monitor; a computer monitor; a television; a tuner; a radio; a satellite radio; a music player; a digital music player; a portable music player; a digital video player; a video player; a digital video disc (DVD) player; a portable digital video player; an automobile; a vehicle component; avionics systems; a drone; and a multicopter.

### Claim 10

A slave integrated circuit (IC) comprising:
a bus interface configured to be coupled to a SOUNDWIRE bus;
a transceiver coupled to the bus interface; and
a control system operatively coupled to the transceiver and configured to:
receive an instruction from a master IC through the SOUNDWIRE bus to prepare to assume sub-master control of the SOUNDWIRE bus; and
assume the sub-master control of the SOUNDWIRE bus by acknowledging a handover command from the master IC.

### Claim 11 (depends on 10)

The slave IC of claim 10, further comprising a clock source and wherein the control system is further configured to use the clock source to provide a clock signal to the SOUNDWIRE bus when the control system assumes the sub-master control of the SOUNDWIRE bus.

### Claim 12 (depends on 10)

The slave IC of claim 10, wherein the control system is further configured to own control information of the SOUNDWIRE bus when the control system assumes the sub-master control of the SOUNDWIRE bus.

### Claim 13 (depends on 10)

The slave IC of claim 10, wherein the control system is further configured to provide an indication that the slave IC is prepared to assume the sub-master control of the SOUNDWIRE bus.

### Claim 14 (depends on 10)

The slave IC of claim 10, wherein the control system is further configured to release master duties back to the master IC.

### Claim 15

A method comprising:
commencing operation with a plurality of devices coupled to a communication bus, wherein a first device of the plurality of devices operates as a master device and other devices of the plurality of devices operate as slave devices;
instructing, through the communication bus, one of the slave devices to prepare to assume sub-master control of the communication bus; and
passing master duties from the master device to the one of the slave devices by transmitting a handover command across the SOUNDWIRE bus and transmitting a handover frame to mark passed control.

### Claim 16 (depends on 15)

The method of claim 15, further comprising determining that the one of the slave devices is capable of operating as a sub-master of the communication bus.

### Claim 17 (depends on 16)

The method of claim 16, wherein determining that the one of the slave devices is capable of operating as the sub-master of the communication bus comprises reading a discoverable (DISCO) file associated with the one of the slave devices.

### Claim 18 (depends on 15)

The method of claim 15, wherein the communication bus is a SOUNDWIRE communication bus.

### Claim 19 (depends on 15)

The method of claim 15, further comprising placing the master device into a sleep or low-power mode after passing the master duties.

### Claim 20 (depends on 15)

The method of claim 15, further comprising resuming the master duties by the master device.

### Claim 21 (depends on 15)

The method of claim 15, wherein passing the master duties comprises having the one of the slave devices provide a clock signal to the communication bus.

### Claim 22 (depends on 15)

The method of claim 15, wherein passing the master duties comprises having the one of the slave devices own control information passed on the communication bus.

### Claim 23

A SOUNDWIRE system comprising:
a SOUNDWIRE bus;
a master integrated circuit (IC) comprising:
a master bus interface configured to be coupled to the SOUNDWIRE bus;
a master transceiver coupled to the master bus interface; and
a master control system operatively coupled to the master transceiver; and
a slave IC comprising:
a slave bus interface configured to be coupled to the SOUNDWIRE bus;
a slave transceiver coupled to the slave bus interface; and
a slave control system operatively coupled to the slave transceiver;
wherein the master control system is configured to:
instruct the slave control system to prepare to assume sub-master control of the SOUNDWIRE bus; and
pass master duties to the slave IC by sending a handover command across the SOUNDWIRE bus and sending a handover frame to mark passed control.

### Claim 24 (depends on 23)

The SOUNDWIRE system of claim 23, wherein the master IC and the slave IC are within a single system on a chip (SoC).

### Claim 25 (depends on 23)

The SOUNDWIRE system of claim 23, wherein the slave control system is configured to alert the master IC that the slave IC is ready to assume the sub-master control of the SOUNDWIRE bus.

### Claim 26 (depends on 23)

The SOUNDWIRE system of claim 23, wherein the slave IC comprises a clock source and, on assumption of the sub-master control of the SOUNDWIRE bus, the slave IC provides a clock signal to the SOUNDWIRE bus.