The graceful reset logic splits the RST_IN port into the RST_BUS and RST_LOGIC
ports. The RST_BUS port is for when the entire PCIe (or whatever) bus is
undergoing reset and the RIFFA logic should not worry about corrupting any state
by terminating a packet early (causing a malformed packet). RST_LOGIC is for logic resets, where PCIe state is not affected and may be corrupted by a malformed packet.
The reset_controller module will safely reset a single stage pipeline without
using an asychronous reset (bleh). It is intended for use in the TX engines,
where it will control the output stage of the engine, and provide a gracefull
end-of-packet reset.
Bug caused received 128-bit Request Headers without payload to signal data word valid one cycle early. May not be a final fix. Unlikely to affect current users.
Expanded DONE_RST into four signals, for each of the four engine interfaces. In
the ultrascale engines, wired up all of the RST and DONE_RST signals. Quickly tested the logic in a power-on-reset like situation, no guarantees on graceful in-transmission resets. Classic engines will have to wait.
Still need to propagate the changes and hook the resets up in the formatters,
multiplexers, etc. RST_BUS will be the equivalent of a PCIe PERST Pin reset, a
general inelegant reset where formatting is disregarded. RST_LOGIC is a reset
caused by application or higher level logic, where formatting needs to be
considered so that the bus does not lock up. DONE_RST will signal that the
engine layer has finished resetting, and is ready to transmit data.
The C_VALUE parameter sets the reset value of each bit in the shift
register. All bits will get the same value, individual setting of reset values
is not implemented.
Most of this documentation is identical to what you can find in the RIFFA 2.2
distribution. I have added Chapter 6 describing the architecture of RIFFA and
should help those who wish to help develop or modify RIFFA in the future.
