Link role determination in a dual-mode Peripheral Component Interconnect express (PCIe) device

A method for configuring a dual-mode Peripheral Component Interconnect express (PCIe) device to operate in a root complex (RC) mode or an endpoint mode, comprising:

• initializing the dual-mode PCIe device into the RC mode;
• performing a configuration and initiation sequence on a wire-based PCIe link coupled to the dual-mode PCIe device;
• determining a link state of the wire-based PCIe link upon completion of the configuration and initiation sequence;
• using a random delay when the link state indicates that the configuration and initiation sequence performed on the wire-based PCIe link is unsuccessful;
• and
• switching the dual-mode PCIe device to the endpoint mode at expiration of the random delay.

A Peripheral Component Interconnect express (PCIe) system, comprising:

• a dual-mode PCIe device configured to operate in a root complex (RC) mode or an endpoint mode, comprising:
• a bus interface configured to be coupled to a wire-based PCIe link;
• and
• control circuitry configured to:
• initialize the dual-mode PCIe device into the RC mode;
• perform a configuration and initiation sequence on the wire-based PCIe link via the bus interface;
• determine a link state of the wire-based PCIe link upon completion of the configuration and initiation sequence;
• use a random delay when the link state indicates that the configuration and initiation sequence performed on the wire-based PCIe link is unsuccessful;
• and
• switch the dual-mode PCIe device to the endpoint mode at expiration of the random delay;
• and
• a second dual-mode PCIe device configured to operate in the RC mode or the endpoint mode, comprising:
• a second bus interface configured to be coupled to the wire-based PCIe link;
• and
• second control circuitry configured to:
• initialize the second dual-mode PCIe device into the RC mode;
• perform a second configuration and initiation sequence on the wire-based PCIe link via the second bus interface;
• determine a second link state of the wire-based PCIe link upon completion of the second configuration and initiation sequence;
• use a second random delay when the second link state indicates that the second configuration and initiation sequence performed on the wire-based PCIe link is unsuccessful;
• and
• switch the second dual-mode PCIe device to the endpoint mode at expiration of the second random delay.

A dual-mode Peripheral Component Interconnect express (PCIe) device configured to switch dynamically between a root complex (RC) mode and an endpoint mode, comprising:

• a bus interface configured to be coupled to a wire-based PCIe link;
• and
• control circuitry configured to:
• initialize the dual-mode PCIe device into the RC mode;
• perform a configuration and initiation sequence on the wire-based PCIe link via the bus interface;
• determine a link state of the wire-based PCIe link upon completion of the configuration and initiation sequence;
• and
• switch to the endpoint mode when the link state indicates that the configuration and initiation sequence performed on the wire-based PCIe link is unsuccessful and after expiration of a delay.