SPRUI30H November 2015 – May 2024 DRA745 , DRA746 , DRA750 , DRA756
The power state of a PCIe controller port is described by four different FSMs, each running at a different level of the protocol, each with its own independent state. The FSMs are covered in Section 24.9.4.5.1.1 through Section 24.9.4.5.1.2.
Table 24-499summarizes the typical power stable state combinations, namely the combinations of states the controller can settle into, after a number of potential transitions and transient states, and assuming that the lowest power state possible is used.
The PCIe standard defined optional gating of the reference clock on PCIe_PHY PLL input (and therefore of the PIPE clock) when in L1-state is not supported. As shown in the Table 24-499, the PIPE clock is always running while link is in L1.
Device D-state | Link L-state | PHY LTSSM state | PIPE power down | PIPE clock(1) | Vmain | LP_CLK(4) (auxiliary clock) | Slave Idle | Master Standby |
---|---|---|---|---|---|---|---|---|
D0_uninitialized(2) | LDn | Detect | P1 | OFF | don't care | ON | 1 | 1 |
D0_uninitialized | L0 | n/a | P0 | ON | ON | ON | 0 | 1 |
D0_active | L0 | L0 | P0 | ON | ON | ON | 0 | 0/1(3) |
D0_active | L0s | L0s | P0s | ON | ON | ON | 0 | 0/1(3) |
D0_active | L1 | L1 | P1 | ON | ON | ON | 0 | 0/1(3) |
D1 | L1 | L1 | P1 | ON | ON | ON | 0 | 1 |
D2 | L1 | L1 | P1 | ON | ON | ON | 0 | 1 |
D3_hot | L1 | L1 | P1 | ON | ON | ON | 0 | 1 |
D3_cold | L3 | n/a | P2 | OFF | OFF | OFF | 1 | 1 |