The receive path functions include the
tasks that the PHY and MAC must perform when the PHY receives signals from the link
partner to exit the LPI state.
In the receive path, when the PHY
receives the signals from the link partner to enter into the LPI state, the PHY and
MAC perform the following tasks:
- The PHY asserts RX_ER
- The PHY sets RXD[7:0] to 0x01
- The PHY de-asserts RX_DV
- The MAC updates the RLPIEN bit of the MAC_LPI_Control_Status
register and immediately generates an interrupt
- The PHY maintains the same state of the RX_ER, RXD, and RX_DV
signals for the entire duration during which it remains in the LPI state.
- If the LPI pattern is detected for a very short
duration (that is, less than two cycles of Rx clock), the MAC does not
enter the Rx LPI mode.
- If the duration between end of the current Rx LPI
pattern and start of the next Rx LPI pattern, is very short (that is,
less than two cycles of Rx clock), then the MAC exits and again enters
the Rx LPI mode. The MAC does not give the Rx LPI Exit and Entry
interrupts
When the PHY receives signals from the
link partner to exit the LPI state, the PHY and MAC perform the following tasks:
- The PHY de-asserts RX_ER and returns to a normal inter-packet
state.
- The MAC updates the RLPIEX bit of the MAC_LPI_Control_Status
register and generates an interrupt immediately. The sideband signal lpi_intr_o
(synchronous to Rx clock) is also asserted.
Figure 43-18 shows the behavior of RX_ER, RX_DV, and RXD[3:0] signals during the LPI mode
transitions.