Link power savings with state retention
First Claim
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1. An apparatus comprising:
- a first agent, wherein the first agent is coupled to a second agent via a serial link, and the first agent comprises;
link layer logic to;
indicate to a physical layer of the first agent that the first agent is to enter a low power link state; and
transmit a link entry signal to the second agent;
the physical layer of the first agent, wherein the physical layer is to comprise an electrical sub-block and logical sub-block and is to enter the low power link state based on an acknowledgement to the link entry signal by the second agent, 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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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
20 Claims
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1. An apparatus comprising:
a first agent, wherein the first agent is coupled to a second agent via a serial link, and the first agent comprises; link layer logic to; indicate to a physical layer of the first agent that the first agent is to enter a low power link state; and transmit a link entry signal to the second agent; the physical layer of the first agent, wherein the physical layer is to comprise an electrical sub-block and logical sub-block and is to enter the low power link state based on an acknowledgement to the link entry signal by the second agent, 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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method comprising:
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indicating to a physical layer of a first agent, by a link layer of the first agent, that the first agent is to enter a low power link state; transmitting a link entry signal from the first agent to a second agent to indicate to the second agent that the first agent is to enter the low power link state; receiving an acknowledgement from the second agent over a serial link, wherein the acknowledgement is to be transmitted in response to receipt of the link entry signal by the second agent; sending an in-band reset from the first agent to the second agent; the first agent entering the low power link state based on the acknowledgement from the second agent; exiting the low power link state on or after expiration of a detect hold-off period, wherein, during the low power link state, the first agent is to retain its link state. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. A system comprising:
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means for indicating to a physical layer of a first agent that the first agent is to enter a low power link state; means for transmitting a link entry signal from the first agent to a second agent over a serial link; means for receiving an acknowledgement of the link entry signal from the second agent; means for sending an in-band reset from the first agent to the second agent; means for entering the low power link state at the first agent based on the acknowledgement from the second agent; and means for exiting the low power link state on or after expiration of a detect hold-off period, wherein, during the low power link state, the first agent is to retain its link state.
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Specification