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Chapter 7: GTP Receiver (RX)
Table 7-33: Channel Bonding Attributes (Continued)
Attribute
CHAN_BOND_SEQ_LEN_0
CHAN_BOND_SEQ_LEN_1
PCI_EXPRESS_MODE_0
PCI_EXPRESS_MODE_1
Description
Enabling Channel Bonding
Each GTP transceiver includes a circuit that performs channel bonding by controlling the
pointers of the RX elastic buffer. To use channel bonding, the RX_BUFFER_USE attribute
must be TRUE to turn on the elastic buffer.
Each GTP transceiver has a channel bonding circuit. Configuring a GTP transceiver for
channel bonding requires the following steps:
1.
2.
3.
4.
5.
Channel Bonding Mode
The channel bonding mode for each GTP transceiver determines whether channel bonding
is active and whether the GTP transceiver is the master or a slave. Each set of channel-
bonded GTP transceivers must have one master and can have any number of slaves. To
turn on channel bonding for a group of GTP transceivers, one transceiver is set to Master.
The remaining GTP transceivers in the group are set to Slaves.
Connecting Channel Bonding Ports
The channel bonding operation requires connecting the master GTP RXCHBONDO port to
the RXCHBONDI port of all slaves in the group. A direct connection is required for
adjacent GTP transceivers. To directly connect a master to a slave:
1.
2.
3.
When GTP transceivers are directly connected, meeting the timing constraints becomes
difficult as the transceivers get further apart. The solution to this problem is connecting the
transceivers using daisy chaining. Daisy chaining is performed using the
CHAN_BOND_LEVEL signal to allow additional pipeline stages between the master and
the slave. The RXCHBONDO port of each slave is used as a pipeline stage in the
178
Define the length in bytes of the channel bonding sequence (1 to 4 bytes) that
the transceiver matches to detect opportunities for channel bonding.
Setting this attribute to TRUE enables certain operations specific to PCI Express,
specifically, recognizing TXELECIDLE = 1, TXCHARDISPMODE = 1,
TXCHARDISPVAL = 0 as a request to power down the channel.
TXCHARDISPMODE = 1 and TXCHARDISPVAL = 0 encode the PIPE
interface signal TXCompliance = 1 of the PIPE (the latter two values being the
encoding for PIPE and enabling special support for FTS lane deskew.
Set the channel bonding mode for each GTP transceiver.
Set master to CHAN_BOND_MODE = MASTER.
Set slave to CHAN_BOND_MODE = SLAVE.
Connect the channel bonding port from the master to each slave, either directly or by
daisy chaining.
Set the channel bonding sequence and detection parameters.
Connect the RXCHBONDO port of the master to the RXCHBONDI port of the slave.
Set the CHAN_BOND_LEVEL of the master to 1.
Set the CHAN_BOND_LEVEL of each slave to 0.
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Description
Virtex-5 RocketIO GTP Transceiver User Guide
UG196 (v1.3) May 25, 2007
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