User Manual
BCM1250/BCM1125/BCM1125H
10/21/02
B r o a d c o m C o r p o r a t i o n
Document
1250_1125-UM100CB-R
Section 8: PCI Bus and HyperTransport Fabric Page
251
Table 149: HyperTransport SRI Command Register - Offset 50 Bits [31:16]
Bits
Name
Default
Description
0
SipReady
R/W 1’b0
System Initialization Process Ready. This bit should be set by software when the
SRI initialization process is complete. The LDT bridge will be held in reset until
this bit is set.
1
SyncPtrCtl
R/W 1’b0
This bit should be set to enable synchronous pointer control. If the interface is
synchronous the pointers in the receive FIFO are moved according to a fixed
pattern based on the ratio of the load and unload clocks. If the interface is
asynchronous the pointers are moved by sampling the incoming receive clock
and counting the number of edges.
2
ReduceSyncZero
R/W 1’b0
If this bit is set only 128 bit times of zeros will be sent during link initialization rather
than the standard 512 bit times. Only set during testing.
3
DisMultTxVld
R/W 1’b0
If clear (default), all 3 virtual channels can send requests simultaneously. If set,
only one channel can make a request at a time (as in RevId). This bit is for
debug use only.
8:4
RxMargin
R/W 5’h0
This sets the offset between the receive FIFO load and unload pointers.
9
sriLdtPLLCompat
R/W 1’b0
This bit should be set for compatibility with 0.17 HyperTransport devices.
It modifies the behavior for updating the LdtLinkFreq register (the one visible to
programmer) and moving it into LdtPLLFreq (the shadow copy used to control the
PLL).
Older fixed frequency devices need this bit set, so a link cold reset does not alter
the link frequency. HyperTransport Rev 1.0 devices reset their link frequency to
200 MHz on a link cold reset.
sriLdtPLLCompat set to 1 => compatible with API AP1011 / SiPackets SP1011
sriLdtPLLCompat set to 0 => comply with 1.0 spec.
This table summarizes the behavior on reset:
LdtLinkFreq LdtPLLFreq
System reset
200MHz
200MHz
Link cold reset
Compat == 0
200MHz
200MHz
Compat == 1
No Change
No Change
Link warm reset
Compat == 0
No Change
copied from LdtLinkFreq
Compat == 1
No Change
No Change
10
exp_endian
R/W 1’b0
Selects endian policy for expansion space. If this bit is clear then all of the
expansion space will use the match byte lane policy. If the bit is set then
address bit [38] is used to select the endian policy and the address bit is cleared
as the request passes through the bridge.
11
reserved
R/O 1’b0
Reserved
14:12
TxInitialOffset
R/W
3’b000
This sets the initial offset between the transmit FIFO unload and load pointers.
15
sriLinkFreqDirect
R/W 1’b0
If this bit is clear the HyperTransport link frequency is set according to the
HyperTransport specification revision 1.0. If it is clear a wider range of frequencies
can be set. See
.
Table 150: HyperTransport Isochronous BAR - Offset 5C Bits [31:0]
Bits
Name
Default
Description
0
isocEn
R/W 1’b0
If this bit is set then the IsocBAR and IsocIgnMask are used to force inbound
transactions within the specified range to behave as if their Isochronous bit is set.
31:1
isocBase
R/W 31’b0 This register sets the address bits 35:5 that are compared to force the iscochronous
bit. See