
TI Extension Registers
195
September 2005
SCPS110
Table 93. Link Enhancement Register Description (Continued)
BIT
FIELD NAME
TYPE
DESCRIPTION
6
RSVD
R
This bit is not assigned in the PCIxx12 follow-on products, because this bit location loaded by the serial
EEPROM from the enhancements field corresponds to bit 23 (programPhyEnable) in the host
controller control register at OHCI offset 50h/54h (see Section 8.16).
53
RSVD
R
Reserved. Bits 53 return 000b when read.
2
RSVD
R
Reserved. Bit 2 returns 0b when read.
1
enab_accel
RW
Enable acceleration enhancements. OHCI-Lynx
compatible. When bit 1 is set to 1b, the PHY layer
is notified that the link supports the IEEE Std 1394a-2000 acceleration enhancements, that is,
ack-accelerated, fly-by concatenation, etc. It is recommended that this bit be set to 1b. The default
value for this bit is 0b.
0
RSVD
R
Reserved. Bit 0 returns 0b when read.
This bit is cleared only by the assertion of GRST.
9.5
Timestamp Offset Register
The value of this register is added as an offset to the cycle timer value when using the MPEG, DV, and CIP
enhancements. A timestamp offset register is implemented per isochronous transmit context. The n value
following the offset indicates the context number (n = 0, 1, 2, 3,
…, 7). These registers are programmed by
software as appropriate. See Table 94 for a complete description of the register contents.
TI extension register offset:
A90h + (4*n)
Register type:
Read/Write, Read-only
Default value:
0000 0000h
BIT NUMBER
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
RESET STATE
0
BIT NUMBER
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
RESET STATE
0
Table 94. Timestamp Offset Register Description
BIT
FIELD NAME
TYPE
DESCRIPTION
31
DisableInitialOffset
RW
Bit 31 disables the use of the initial timestamp offset when the MPEG2 enhancements are enabled.
A value of 0b indicates the use of the initial offset, a value of 1b indicates that the initial offset must
not be applied to the calculated timestamp. This bit has no meaning for the DV timestamp
enhancements. The default value for this bit is 0b.
3025
RSVD
R
Reserved. Bits 3025 return 000000b when read.
2412
CycleCount
RW
This field adds an offset to the cycle count field in the timestamp when the DV or MPEG2
enhancements are enabled. The cycle count field is incremented modulo 8000; therefore, values in
this field must be limited between 0 and 7999. The default value for this field is all 0b..
110
CycleOffset
RW
This field adds an offset to the cycle offset field in the timestamp when the DV or MPEG2
enhancements are enabled. The cycle offset field is incremented modulo 3072; therefore, values in
this field must be limited between 0 and 3071. The default value for this field is 000h.