Display link power management using in-band low-frequency periodic signaling

1. An apparatus comprising:

a port comprising circuitry to couple the apparatus to a receiver device via one or more intermediate devices over a DisplayPort (DP)-based link;

a processor to generate signals for communication over the DP-based link; and

memory comprising instructions to cause the processor to:

initiate a transition to a low power state in the receiver device and the intermediate devices of the DP-based link by transmitting a number of sleep pattern signals over the DP-based link equal to a number of the intermediate devices plus one; and

initiate a transition to an active power state in devices of the DP-based link by transmitting a wake pulse sequence and physical link establishment signal pattern over the DP-based link.

2. The apparatus of claim 1 , wherein each sleep pattern is 80 bits in 8b/10b encoding.

3. The apparatus of claim 1 , wherein each sleep pattern is 129 bits in 128b/132b encoding.

4. The apparatus of claim 1 , wherein the instructions are to transmit scrambled zeroes between each of the transmitted sleep patterns.

5. The apparatus of claim 4 , wherein the scrambled zeroes are at least 2560 bits in in 8b/10b encoding.

6. The apparatus of claim 4 , wherein the scrambled zeroes are at least 4096 bits in 128b/132b encoding.

7. The apparatus of claim 1 , wherein the instructions are to transmit a wake pulse sequence that includes a number of fixed length pulses.

8. The apparatus of claim 7 , wherein the instructions are to transmit at least seven pulses having a pulse length between 25 ns-50 ns.

9. The apparatus of claim 7 , wherein the instructions are to transmit the wake pulse sequence over a period of 175 ns-400 ns.

10. The apparatus of claim 1 , wherein the instructions are to output a common mode voltage between the wake pulse sequence and the physical link establishment signal pattern.

11. The apparatus of claim 10 , wherein the instructions are to output the common mode voltage over a period of 80 ns-120 ns.

12. The apparatus of claim 1 , wherein the instructions are to initiate the transition to the active power state by further transmitting signals to establish a clock signal in the devices of the DP-based link.

13. The apparatus of claim 1 , wherein the intermediate devices comprise link-training tunable PHY repeaters (LTTPRs).

14. The apparatus of claim 1 , wherein the instructions cause the processor to transmit the sleep pattern signals and the wake pulse sequence over the main link of the DP-based link.

15. One or more non-transitory computer-readable media comprising instructions that, when executed by a machine, cause the machine to:

cause a video source device coupled to a display over a DisplayPort (DP)-based link to initiate a transition to a low power state in the devices of the DP-based link by transmitting a number of sleep pattern signals over the DP-based link equal to one plus a number of intermediate devices on the DP-based link between the video source and the display; and

cause the video source device to initiate a transition to an active power state in the devices of the DP-based link by transmitting a wake pulse sequence and physical link establishment signal pattern over the DP-based link.

16. The computer-readable media of claim 14 , wherein the instructions are to transmit scrambled zeroes between each of the transmitted sleep patterns.

17. The computer-readable media of claim 15 , wherein the instructions are to transmit a wake pulse sequence that includes a number of fixed length pulses.

18. The computer-readable media of claim 15 , wherein the instructions are to output a common mode voltage between the wake pulse sequence and the physical link establishment signal pattern.

19. The computer-readable media of claim 15 , wherein the instructions are to initiate the transition to the active power state by further transmitting signals to establish a clock signal in the devices of the DP-based link.

20. The computer-readable media of claim 15 , wherein the instructions cause the video source device to transmit the sleep pattern signals and the wake pulse sequence over the main link of the DP-based link.

21. A system comprising:

a display;

one or more intermediate devices; and

a video source device coupled to the display and the intermediate devices over a DisplayPort (DP)-based link, the video source device comprising circuitry to:

initiate a transition to a low power state in the devices of the DP-based link by transmitting a number of sleep pattern signals over the DP-based link equal to the number of repeater devices plus one; and

initiate a transition to an active power state in devices of the DP-based link by transmitting a wake pulse sequence and physical link establishment signal pattern over the DP-based link.

22. The system of claim 21 , wherein the circuitry is to initiate the transition to the active power state by further transmitting signals to establish a clock signal in the devices of the DP-based link.

23. The system of claim 21 , wherein each intermediate device is to transmit the wake pulse sequence to a downstream device of the DP-based link in response to detecting the wake pulse sequence transmitted by an upstream device of the DP-based link.

24. The system of claim 21 , wherein each intermediate device is to transmit the wake pulse sequence to a downstream device of the DP-based link based on detecting the wake pulse sequence and physical link establishment signal pattern transmitted by an upstream device of the DP-based link.

25. The system of claim 21 , wherein the intermediate devices comprise link-training tunable PHY repeaters (LTTPRs).