State change in systems having devices coupled in a chained configuration
The present disclosure includes methods, devices, and systems for state change in systems having devices coupled in a chained configuration. A number of embodiments include a host and a number of devices coupled to the host in a chained configuration. The chained configuration includes at least one device that is not directly coupled to the host. The at least one device that is not directly coupled to the host is configured to change from a first communication state to a second communication state responsive to receipt of a command from the host.
1. A system, comprising:
a host; and
a number of devices coupled to the host in a chained configuration, wherein:
the chained configuration includes:
a first device directly coupled to the host;
a second device directly coupled to the first device and not directly coupled to the host; and
a third device directly coupled to the second device and not directly coupled to the host;
wherein at least one of the second and third devices is configured to change from a first communication state to a second communication state responsive to receipt of a command from the host, and wherein the second communication state is a higher speed communication state than the first communication state.
2. The system of claim 1 , wherein:
the at least one of the second and third devices includes an input port and an output port; and
the at least one of the second and third devices is configured to change the input port and the output port from a first state to a second state responsive to receipt of the command from the host.
3. The system of claim 2 , wherein the at least one of the second and third devices is configured to change the input port and the output port from a first speed state to a second speed state, responsive to receipt of the command from the host, and wherein the second speed state is a higher speed state than the first speed state.
4. The system of claim 2 , wherein the host is not aware of a change of the input port and the output port from the first state to the second state.
5. The system of claim 1 , wherein the at least one of the second and third devices is configured to change from the second communication state to a third communication state responsive to receipt of an additional command from the host.
6. The system of claim 5 , wherein the host is configured to send the additional command to the at least one of the second and third devices without receiving an acknowledgement of the command.
7. The system of claim 5 , wherein:
the at least one of the second and third devices is configured to send an acknowledgement of the command to the host responsive to the change of the at least one of the second and third devices from the first communication state to the second communication state; and
the host is configured to send the additional command to the at least one of the second and third devices responsive to receipt of the acknowledgement.
8. The system of claim 5 , wherein:
the host is aware of an amount of time associated with a change of the at least one of the second and third devices from the first communication state to the second communication state; and
the host is configured to send the additional command to the at least one of the second and third devices responsive to an expiration of the amount of time.
9. The system of claim 1 , wherein each of the devices in the chained configuration are configured to communicate information at a rate in a first communication state that is as fast as or faster than an information communication rate of any downstream device in a second communication state in the chained configuration.
10. The system of claim 1 , wherein:
the at least one of the second and third devices is configured to use a first amount of power while in the first communication state; and
the at least one of the second and third devices is configured to use a second amount of power while in the second communication state;
wherein the first amount of power is different than the second amount of power.
11. A method for operating a system, comprising:
receiving, by a device, a command from a host, wherein:
the device is coupled to the host in a chained configuration, wherein the chained configuration includes:
a first device directly coupled to the host;
a second device directly coupled to the first device and not directly coupled to the host; and
a third device directly coupled to the second device and not directly coupled to the host; and
the device is not directly coupled to the host; and
changing a state of an input port and an output port of the device responsive to the command, wherein changing the state of the input port and the output port includes changing the state of the input port and the output port from a first speed state to a second speed state, and wherein the second speed state is a higher speed state than the first speed state.
12. The method of claim 11 , wherein the first speed state is a sleep state.
13. The method of claim 11 , wherein the method includes:
sending an acknowledgement of the command from the device to the host responsive to changing the state of the input port and the output port;
receiving, by the device, an additional command from the host responsive to the acknowledgement; and
changing the state of the input port and the output port responsive to the additional command.
14. The method of claim 11 , wherein the method includes:
receiving, by the device, an additional command from the host responsive to an expiration of an amount of time associated with changing the state of the input port and the output port of the device; and
changing the state of the input port and the output port responsive to the additional command.
15. The method of claim 11 , wherein the method includes:
receiving, by the device, an additional command from the host without sending an acknowledgement of the command from the device to the host responsive to changing the state of the input port and the output port; and
changing the state of the input port and the output port responsive to the additional command.
16. A method for operating a system, comprising:
receiving, by a device, a command from a host, wherein:
the device is coupled to the host in a chained configuration, wherein the chained configuration includes:
a first device directly coupled to the host;
a second device directly coupled to the first device and not directly coupled to the host; and
a third device directly coupled to the second device and not directly coupled to the host; and
the device is not directly coupled to the host; and
changing a communication state of the device from a first communication state to a second communication state responsive to the command, wherein the second communication state is a higher speed communication state than the first communication state.
17. The method of claim 16 , wherein the method includes:
receiving, by the device, an additional command from the host; and
changing the communication state of the device responsive to the additional command.
18. The method of claim 17 , wherein the additional command from the host is received responsive to an expiration of an amount of time associated with changing the communication state of the device.
19. The method of claim 17 , wherein the additional command from the host is received without sending an acknowledgement of the command from the device to the host responsive to changing the communication state of the device.
20. The method of claim 16 , wherein receiving the command from the host includes:
receiving, by an additional device, the command from the host, wherein the host is directly coupled to the additional device; and
receiving, by the device, the command from the additional device, wherein the additional device is directly coupled to the device.