
DATA SHEET
PM7367 FREEDM-32P32
ISSUE 2
PMC-1991499
FRAME ENGINE AND DATA LINK MANAGER
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMER’S INTERNAL USE
56
Field
Description
CE
The Chain End (CE) bit is used by the host to indicate
the end of a linked list of TDs presented to the TMAC.
The linked list can contain one or more packets as
delineated by the M bit (see above). When CE is set
to logic 1, the current TD is the last TD of a linked list
of TDs. When CE is set to logic 0, the current TD is
not the last TD of a linked list. When the current TD
is not the last of the linked list, the Host Next TD
Pointer[13:0] field is valid, otherwise the field is not
valid.
Note: When CE is set to logic 1, the only valid value
for M is logic 0.
Note: When presenting raw (i.e. unpacketised) data
for transmission, the host should code the M and CE
bits as for a single packet chain, i.e. M=1, CE=0 for
all TDs except the last in the chain and M=0, CE=1
for the last TD in the chain.
TCC[6:0]
The Transmit Channel Code (TCC[6:0]) field is used
by the host to indicate with which channel a TD is
associated. All TD in a chain must be associated with
the same channel, i.e. have this field set to the same
value.
Legal values for this field are 0 to 31.
TMAC Next TD Pointer
[13:0]
The TMAC Next TD Pointer[13:0] bits are used to
store TDRs which permits the TMAC to create linked
lists of TDs passed to it via the TDRR queue. The
TDs are linked with other TDs belonging to the same
channel and same priority level. In the case that data
presented to the TMAC is returned to the host due to
a channel becoming unprovisioned, a TDR pointing to
the start of the per-channel linked list of TDs is placed
on the TDRF queue. It is the responsibility of the
host to follow the TMAC and host links in order to
recover all the buffers.
ABT
The Abort (ABT) bit is used by the host to abort the
transmission of a packet. When ABT is set to logic 1,
the packet will be aborted after all the data in the
buffer has been transmitted. If ABT is set to logic 1 in
the current TD, the M bit must be set low and the CE
bit must be set to high..