Systems and methods for avoiding retraining a communication bus after a link failure

A package comprising:

• a communication bus comprising a default sideband, a redundant sideband, and a main band;
• a first chiplet comprising:
• a first port coupled to the communication bus;
• a first multiplexer coupled to the first port and configured to route signals to the default sideband on the communication bus during normal operation and to the redundant sideband on the communication bus when a sideband fault occurs;
• and
• a first control circuit coupled to the first multiplexer, the first control circuit configured to:
• detect the sideband fault on the default sideband;
• responsive to detection of the sideband fault, instruct the first multiplexer to send signals to the redundant sideband;
• and
• while sending the signals to the redundant sideband, maintain operation of the main band of the communication bus;
• and
• a second chiplet comprising:
• a second port coupled to the communication bus;
• and
• a second control circuit configured to:
• responsive to receiving a signal on the redundant sideband, allow use of the redundant sideband while maintaining the operation of the main band.

A method of operating a communication bus comprising:

• detecting a fault on a default sideband link on the communication bus;
• responsive to detecting the fault, routing sideband signals on a redundant sideband link comprising lanes different than lanes used by the default sideband link;
• and
• maintaining operation of a main band link on the communication bus while using the redundant sideband link.