US Patent 11853251 On-die chip-to-chip (C2C) link state monitor

Disclosed are techniques for chip-to-chip (C2C) serial communications, such as communications between chiplets on a multi-chip package. In some aspects, a method of on-die monitoring of C2C links comprises detecting a change of the C2C link from a first link state to a second link state and storing link state change information in an on-die first-in, first-out (FIFO) buffer. The link state change information indicates the first link state, the duration of time the C2C link was in the first link state, and the speed of the C2C link in the first link state. Upon detecting a request for link state change information, link state change information is retrieved from the FIFO buffer and transmitted serially to an output pin of the die, such as a general purpose input/output (GPIO) pin.