LINK POWER SAVINGS WITH STATE RETENTION
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Abstract
Methods and apparatus relating to link power savings with state retention are described. In one embodiment, one or more components of two agents coupled via a serial link are turned off during idle periods while retaining link state in each agent. Other embodiments are also disclosed.
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Citations
46 Claims
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1-20. -20. (canceled)
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21. An apparatus comprising:
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a first agent to be coupled to a second agent via a link, the first agent to; assert a link entry signal to cause physical layer associated with the first agent to send an in-band reset signal to the second agent; and enter the low power link state in response to an acknowledgement message to the link entry signal from the second agent; wherein an electrical sub-block is to be turned off and power is to be maintained at a logical sub-block of the first agent in the low power link state to preserve configuration of the physical layer associated with the first agent. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
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33. An apparatus comprising:
a controller to interface between at least a first processor to recognize a first instruction set and second processor to recognize a second instruction set that is different from the first instruction set, the controller comprising interface logic to couple to a link comprising a plurality of lanes; the interface logic to; send a link entry signal to indicate that a physical layer is to enter a low power link state, wherein the low power link state comprises a lowest power state available to the link without removing power supplies to the link; and enter the low power link state in response to an acknowledgement to the link entry signal, wherein an electrical sub-block of the physical layer is to be turned off and a logical sub-block of the physical layer is to be functionally shut down with power maintained at the logical sub-block in the low power link state to preserve configuration of the physical layer.
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34. A method comprising:
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asserting a link entry signal to cause a physical layer associated with a first agent to enter a low power link state and send an in-band reset signal to a second agent; receiving an acknowledgment from the second agent, wherein the second agent is to transmit the acknowledgement message in response to a physical layer associated with second agent entering the low power link state; and causing the first agent to enter the low power link state in response to the acknowledgement; wherein an electrical sub-block is to be turned off and power is to be maintained at a logical sub-block of the first agent in the low power link state to preserve configuration of the physical layer associated with the first agent.
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35. An apparatus comprising:
a first agent, wherein the a first agent is communicatively coupled to a second agent via a link, and the first agent comprises; link layer logic to assert a link entry signal to indicate to a physical layer of the first agent that the first agent is to enter a low power link state, wherein the low power link state comprises a lowest power state available to the link without removing power supplies to the link; the physical layer of the first agent, wherein the physical layer is to comprise an electrical sub-block and a logical sub-block and enter the low power link state, wherein, during the low power link state, the electrical sub-block is to be turned off and the logical sub-block is to be functionally shut down with power maintained at the logical sub-block to preserve configuration of the physical layer, and the electrical sub-block is to comprise a front end driver and clock circuitry; detection logic to detect terminations on the link during the low power link state based on a detect hold-off time; and counter logic to maintain a synchronization counter count during the low power link state.
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36. An apparatus comprising:
a first agent, wherein the a first agent is to be communicatively coupled to a second agent via a link, and the first agent comprises; link layer logic to assert a link entry signal to indicate to a physical layer of the first agent that the first agent is to enter a low power link state; and physical layer logic to; send an in-band reset to the second agent; receive an acknowledgement from the second agent; enter the low power link state based on the acknowledgement; and exit the low power link state on or after expiration of a detect hold-off period. - View Dependent Claims (37, 38, 39, 40)
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41. A system comprising:
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a first agent; and a second agent communicatively coupled to the first agent via a serial data link; wherein the first agent is to send a signal to the second agent to indicate an attempt to enter a low power link state, the second agent is to enter the low power link state based on the signal and send an acknowledgment to the first agent, and the first agent is to enter the low power link state based on the acknowledgment, wherein clock circuitry of the first agent is to be turned-off and power is to be maintained at a logical sub-block of the first agent to maintain configuration of a physical layer of the first agent during the low power link state. - View Dependent Claims (42, 43, 44, 45, 46)
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Specification