void __4_1_7__AUTO_NEGOTIATION() { /** * @group: 4.1.7 AUTO-NEGOTIATION * * @description: The device conforms to the auto-negotiation protocol as described by IEEE 802.3. Auto-negotiation allows each port to * operate at either 10BASE-Te, 100BASE-TX or 1000BASE-T by allowing link partners to select the best common mode * of operation. During auto-negotiation, the link partners advertise capabilities across the link to each other and then com- * pare their own capabilities with those they received from their link partners. The highest speed and duplex setting that * is common to the two link partners is selected as the mode of operation. * The following list shows the speed and duplex operation mode from highest to lowest priority. * • Priority 1: 1000BASE-T, full-duplex * • Priority 2: 1000BASE-T, half-duplex * • Priority 3: 100BASE-TX, full-duplex * • Priority 4: 100BASE-TX, half-duplex * • Priority 5: 10BASE-Te, full-duplex * • Priority 6: 10BASE-Te, half-duplex * If the KSZ9477S link partner doesn’t support auto-negotiation or is forced to bypass auto-negotiation for 10BASE-Te * and 100BASE-TX modes, the KSZ9477S port sets its operating mode by observing the signal at its receiver. This is * known as parallel detection, and allows the KSZ9477S to establish a link by listening for a fixed signal protocol in the * absence of the auto-negotiation advertisement protocol. * The auto-negotiation link-up process is shown in Figure 4-1. * * * FIGURE 4-1: AUTO-NEGOTIATION AND PARALLEL OPERATION * * +-----------------------------------------------------------------------------------+ * | | * | +-------------------------+ | * | | START AUTO NEGOTIATION | | * | +-------------------------+ | * | | | * | v | * | +---------------+ | * | NO->| FORCE LINK? |<-- YES | * | +----| SETTING |-----+ | * | | +---------------+ | | * | | | | * | | v | * | | +--------------------------------+ | * | | | BYPASS AUTO NEGOTIATION AND | | * | | | SET LINK MODE | | * | | +--------------------------------+ | * | | | * | v | * | +----+------------------------------------------+ | * | | PARALLEL OPERATION | | * | +-----------------------------------------------+ | * | | | | | * | v v v | * | +----------------------+ +-------------------------+ +-------------------------+ | * | | ATTEMPT AUTO NEG. | | LISTEN 100BASE-TX IDLES | | LISTEN 10BASE-T IDLES | | * | +----------------------+ +-------------------------+ +-------------------------+ | * | | | | | | | * | | +----------------------+-------------------------+ | | * | | | | | * | | v | | * | | +-------------+ | | * | +--------------------->| JOIN FLOW |<-----------------------+ | * | +-------------+ | * | | | * | v | * | +-------------+ | * | NO--| LINK MODE? |-- YES | * | +---| SET? |----+ | * | | +-------------+ | | * | | | | * | v v | * | +--------------------------------+ +-----------------+ | * | | (Loop back to PARALLEL OP) | | LINK MODE SET | | * | +--------------------------------+ +-----------------+ | * | | * +-----------------------------------------------------------------------------------+ * * * For 1000BASE-T mode, auto-negotiation is always required to establish a link. During 1000BASE-T auto-negotiation, * the master and slave configuration is first resolved between link partners. Then the link is established with the highest * common capabilities between link partners. * Auto-negotiation is enabled by default after power-up or hardware reset. Afterwards, auto-negotiation can be enabled * or disabled via bit 12 of the PHY Basic Control Register. If auto-negotiation is disabled, the speed is set by bits 6 and * 13 of the PHY Basic Control Register, and the duplex is set by bit 8. * If the speed is changed on the fly, the link goes down and either auto-negotiation or parallel detection initiate until a * common speed between the KSZ9477S and its link partner is re-established for a link. * If link is already established and there is no change of speed on the fly, the changes (for example, duplex and pause * capabilities) will not take effect unless either auto-negotiation is restarted through bit 9 of the PHY Basic Control Regis- * ter, or a link-down to link-up transition occurs (i.e. disconnecting and reconnecting the cable). * After auto-negotiation is completed, the link status is updated in the PHY Basic Status Register, and the link partner * capabilities are updated in the PHY Auto-Negotiation Link Partner Ability Register, PHY Auto-Negotiation Expansion * Status Register, and PHY 1000BASE-T Status Register. */ }