Sideband signaling over existing auxiliary pins of an interface

An apparatus comprising:

• an interface to couple to a second device over a link to be established using the interface, wherein the interface comprises:
• a set of data pins to support data communication on the link based on an interconnect protocol;
• and
• an auxiliary pin separate from the set of data pins to support the link based on the interconnect protocol, wherein the interconnect protocol defines a set of protocol-defined signals to be communicated on the auxiliary pin;
• and
• circuitry to:
• monitor the auxiliary pin for a sideband signal in a set of sideband signals, wherein the set of sideband signals are outside the set of protocol-defined signals;
• interpret the sideband signal in the set of sideband signals as intended for a particular subcomponent of the apparatus;
• and
• send information to the particular subcomponent based on the sideband signal in the set of sideband signals.

A system comprising:

• a first device comprising a first interface;
• and
• a second device comprising a second interface, wherein the first and second devices are coupled via the first and second interfaces, each of the first and second interfaces comprise respective data pins to support lanes of a data link based on an interconnect protocol, each of the first and second interfaces further comprise a respective auxiliary pin to support a clock power management signal, and the auxiliary pin of the first device is connected to the auxiliary pin of the second device to form an auxiliary connection,
• wherein the second device further comprises auxiliary sideband circuitry to:
• generate hint data;
• and
• send the hint data as a sideband signal to the first device over the auxiliary connection, wherein the sideband signal is distinct from the clock power management signal.