RX Scaled Flow Control
The PCIe Controller advertises the maximum available header and payload credit limits for posted, non-posted, and completion RX buffers. When scaled flow control is activated, the PCIe Controller advertises a scale factor of 01 by default.
The firmware can:
- Override the scale and limit values prior to link training.
- Program the scale factor in the Local Management DL Layer flow control scaling management Register.
- Program the limit value in the Local Management Receive Credit Limit Register 0/1.
Additionally, the firmware must ensure that the programmed values do not exceed the maximum credits that were present upon reset.
If Flow Control Scaling is not activated during DL Feature Exchange, the PCIe Controller overrides the programmed scale factor with 00. The programmed credit values are adjusted to the scale factor of 00.