Visible to Intel only — GUID: jsz1488565703636
Ixiasoft
Visible to Intel only — GUID: jsz1488565703636
Ixiasoft
51.3.3. MAC Speed
Mac speed information is used to select different transmit clock sources.
Arria® V or Cyclone® V HPS cores do not provide mac speed information to the FPGA fabric. Therefore a control register is defined in the Intel FPGA HPS EMAC Interface Splitter core for software to configure it correctly according to the speed used by HPS EMAC and PHY device.
The Intel® Arria® 10 HPS provides mac speed information to the FPGA fabric. The control register in the Intel FPGA HPS EMAC Interface Splitter core is automatically removed.
The two incoming mac_speed bits going into Intel FPGA HPS GMII to TSE 1000BASE-X/SGMII PCS bridge is treated as asynchronous and static. Only 1 bit (mac_speed[1]]) is being used to determine whether the MAC is operating in GMII or MII mode. Therefore a double synchronizer is enough to synchronize (mac_speed[1]). No additional filtering logic is needed unless both bits are used.