Modular low latency electrical sequence for die-to-die interface
A system comprising a first die comprising a first receiver and a first transmitter to couple to a link between the first die and a second die comprising a second receiver and a second transmitter; and circuitry to place the first receiver and first transmitter into isolation modes; provide a first signal to the second die to request placement of the second transmitter into a deisolation mode; place the first receiver and first transmitter into deisolation modes responsive to a second signal from the second die; and provide a third signal to the second die to request placement of the second receiver into a deisolation mode.
1. A system comprising:
a first die in a package, the first die comprising:
a first receiver and a first transmitter to couple to a link between the first die and a second die in the package, the second die comprising a second receiver and a second transmitter; and
circuitry to:
place the first receiver and first transmitter into isolation modes;
provide a first signal to the second die to request placement of the second transmitter into a deisolation mode;
place the first receiver and first transmitter into deisolation modes responsive to a second signal from the second die; and
provide a third signal to the second die to request placement of the second receiver into a deisolation mode.
2. The system of claim 1 , wherein:
the first signal is sent over a first wire dedicated to the first signal;
the second signal is sent over a second wire dedicated to the second signal; and
the third signal is sent over a third wire dedicated to the third signal.
3. The system of claim 2 , further comprising the first wire, second wire, and third wire.
4. The system of claim 3 , further comprising the second die.
5. The system of claim 4 , wherein the first die comprises a processor to generate data to be communicated over the link.
6. The system of claim 5 , further comprising a battery communicatively coupled to the processor, a display communicatively coupled to the processor, or a network interface communicatively coupled to the processor.
7. The system of claim 1 , wherein placing the first receiver into an isolation mode comprises driving an output of the receiver to a fixed logical value.
8. The system of claim 1 , wherein placing the first transmitter into an isolation mode comprises driving an output of the transmitter to a low voltage value.
9. The system of claim 1 , wherein placing the first receiver into a deisolation mode comprises configuring the first receiver to output an output of the second transmitter.
10. The system of claim 1 , wherein placing the first transmitter into a deisolation mode comprises configurating the first transmitter to output an output of a protocol layer of the first die.
11. The system of claim 1 , wherein the circuitry is, during a power off flow, to:
transition the first receiver from a deisolation mode to an isolation mode;
transition the first signal to request placement of the second receiver and second transmitter into isolation modes; and
transition the first transmitter from a deisolation mode to an isolation mode responsive to a transition of the second signal.
12. The system of claim 11 , wherein the circuitry is to power off the first receiver and the first transmitter after transitioning the first transmitter to the isolated mode.
13. The system of claim 1 , wherein the first die comprises a central processing unit or graphics processing unit and the second die comprises a system on a die.
14. An apparatus comprising:
a first die in a package, the first die comprising:
a first receiver and a first transmitter to couple to a link between the first die and a second die in the package, the second die comprising a second receiver and a second transmitter; and
circuitry to:
place the first transmitter into an isolation mode when the second receiver is to be powered down; and
place the first receiver into an isolation mode when the second transmitter is to be powered down.
15. The apparatus of claim 14 , wherein placing the first transmitter into the isolation mode comprises driving the output of the first transmitter to a low voltage.
16. The apparatus of claim 14 , wherein placing the first receiver into the isolation mode comprises driving the output of the first receiver to a fixed logical value.
17. The apparatus of claim 14 , wherein the circuitry is to transition a first signal to request isolation or deisolation of the second receiver and the second transmitter.
18. The apparatus of claim 14 , wherein the circuitry is to transition the first receiver and the first transmitter to deisolation modes responsive to a signal received from the second die.
19. An apparatus comprising:
circuitry to bring up a link between a first die in a package and a second die in the package, wherein bringing up the link comprises:
isolating a first transmitter and a first receiver of the first die and a second transmitter and a second receiver of the second die;
deisolating the second transmitter while the first receiver is still isolated;
deisolating the first receiver and the first transmitter while the second receiver is still isolated; and
deisolating the second receiver after the first receiver and the first transmitter are deisolated.
20. The apparatus of claim 19 , the circuitry further to take down the link, wherein taking down the link comprises:
isolating the first receiver;
isolating the second receiver and the second transmitter after isolating the first receiver; and
isolating the first transmitter after isolating the second receiver and the second transmitter.