2.10. Reset

E-tile Hard IP User Guide: E-Tile Hard IP for Ethernet and E-Tile CPRI PHY Intel® FPGA IPs

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2.10. Reset

Ethernet registers control three distinct soft resets:

eio_sys_rst
soft_tx_rst
soft_rx_rst

These soft resets are not self-clearing. The reconfig port clears the soft resets by writing to the appropriate register. The IP core also has three hard reset signals, which are active low:

i_csr_rst_n (100G) / i_sl_csr_rst_n (10G/25G)
i_tx_rst_n (100G) / i_sl_tx_rst_n (10G/25G)
i_rx_rst_n (100G) / i_sl_rx_rst_n (10G/25G)

Figure 34. Conceptual Overview of General IP Core Reset Logic

Asserting the external hard reset i_csr_rst_n/i_sl_csr_rst_n or the soft reset eio_sys_rst returns all Ethernet registers to their original values, including the statistics counters. An additional dedicated reset signal, i_reconfig_reset, resets the transceiver reconfiguration, Ethernet reconfiguration interfaces, and some Ethernet soft registers.

Table 26. Reset Signal FunctionsIn this table, a tick (√) represents the block is reset by the specified reset signal. A dash (—) represents the block is not impacted by the specified reset signal.
Reset Signal	Block
Reset Signal	TX EMIB Interface	TX MAC	TX PCS	TX FEC	TX PMA Interface	TX Statistics	RX EMIB Interface	RX MAC	RX PCS	RX FEC	RX PMA Interface	RX Statistics
`i_sl_csr_rst_n`	√	√	√	—	√	√	√	√	√	—	√	√
`i_csr_rst_n` `eio_sys_rst`	√	√	√	√	√	√	√	√	√	√	√	√
`i_sl_tx_rst_n` `soft_tx_rst` ²³	—	√	√	—	—	—	—	—	—	—	—	—
`i_tx_rst_n` `soft_tx_rst` ²⁴	—	√	√	√	—	—	—	—	—	—	—	—
`i_sl_rx_rst_n` `soft_rx_rst` ²³	—	—	—	—	—	—	—	√	√	—	—	—
`i_rx_rst_n` `soft_rx_rst` ²⁴	—	—	—	—	—	—	—	√	√	√	—	—
`soft_clear_tx_stats`	—	—	—	—	—	√	—	—	—	—	—	—
`soft_clear_rx_stats`	—	—	—	—	—	—	—	—	—	—	—	√

The general reset signals reset the following functions:

soft_tx_rst, i_tx_rst_n/i_sl_tx_rst_n:
- Resets the IP core in the TX direction.
- Resets TX PCS, TX MAC, and TX PMA interface.
- This reset leads to deassertion of the o_tx_lanes_stable output signal.
- In Ethernet Toolkit, perform this reset using the TX MAC and PCS Reset.
soft_rx_rst, i_rx_rst_n/i_sl_rx_rst_n:
- Resets the IP core in the RX direction.
- Resets RX PCS, and RX MAC.
- This reset leads to deassertion of the o_rx_pcs_ready output signal.
- In Ethernet Toolkit, perform this reset using the RX MAC and PCS Reset.
eio_sys_rst, i_csr_rst_n/i_sl_csr_rst_n:
- Resets the IP core. i_csr_rst_n signal is edge sensitive. Perform the reset assertion and deassertion sequence at the i_csr_rst_n 0->1 edge.
- Resets the TX and RX MAC, TX and RX EMIB interface, Ethernet reconfiguration registers, PCS, and TX and RX PMA interfaces.
- This reset leads to deassertion of the o_tx_lanes_stable and o_rx_pcs_ready output signals.
- In Ethernet Toolkit, perform this reset using the Full System Reset.

In addition, the synchronous i_reconfig_reset signal resets the IP core transceiver reconfiguration interface, Ethernet reconfiguration interfaces, and some Ethernet soft registers. i_reconfig_reset signal is synchronous to the i_reconfig_clk and is positive edge triggered.

PMA reset is only required when you change any PMA settings. For PMA reset information, refer to PMA Reset and PMA Analog Reset in the E-Tile Transceiver PHY User Guide.

System Considerations

You should perform a system reset before beginning IP core operation, preferably by asserting and deasserting the i_csr_rst_n/i_sl_csr_rst_n and i_reconfig_reset signals together. Alternatively, you can use eio_sys_rst ²⁵ register instead of i_csr_rst_n/i_sl_csr_rst_n signals.
- To assert i_csr_rst_n/i_sl_csr_rst_n, drive the signal to 0. To deassert i_csr_rst_n/i_sl_csr_rst_n, drive the signal to 1.
- To assert i_reconfig_reset, drive the signal to 1. To deassert i_reconfig_reset, drive the signal to 0. You should access reconfiguration registers 32 µs after the deassertion of i_reconfig_reset.
- To assert eio_sys_rst, write 1'b1 to the 0x310[0] register. To deassert eio_sys_rst, write 1'b0 to the 0x310[0] register. The IP core implements the correct reset sequence to reset the entire IP core.
- For 10GE/25GE multi-channel master-slave configuration (with RS-FEC enabled), all channels must be taken out of the initial reset before each channel can start functioning independently. For more information, refer to Ethernet Adaptation Flow with Non-external AIB Clocking.
- For 10GE/25GE multi-channel non master-slave configuration (with RS-FEC disabled), the master/slave resets can be asserted/deasserted in any order for each of the individual channels.
If you assert the transmit reset when the downstream receiver is already aligned, the receiver loses alignment. Before the downstream receiver loses lock, it might receive some malformed frames.
If you assert the receive reset while the upstream transmitter is sending packets, the packets in transit are corrupted.

²³ This reset is applicable for the 10G/25G Ethernet variant.

²⁴ This reset is applicable for the 100G Ethernet variant.

²⁵ When the eio_sys_rst signal is asserted, the access to any other registers is forbidden. When AN/LT is enabled, eio_sys_rst reset cannot be asserted until AN/LT is complete and enters the data mode.

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E-tile Hard IP User Guide: E-Tile Hard IP for Ethernet and E-Tile CPRI PHY Intel® FPGA IPs

2.10. Reset

System Considerations