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25 subsystem access register – Texas Instruments Dual/Single Socket CardBus and UntraMedia Controller PCI7621 User Manual

Page 178

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7−18

Table 7−21. Link Enhancement Control Register Description (Continued)

BIT

FIELD NAME

TYPE

DESCRIPTION

11

RSVD

R

Reserved. Bit 11 returns 0 when read.

10 ‡

enab_mpeg_ts

RW

Enable MPEG CIP timestamp enhancement. When bit 9 is set to 1, the enhancement is enabled for
MPEG CIP transmit streams (FMT = 20h). The default value for this bit is 0.

9

RSVD

R

Reserved. Bit 9 returns 0 when read.

8 ‡

enab_dv_ts

RW

Enable DV CIP timestamp enhancement. When bit 8 is set to 1, the enhancement is enabled for DV
CIP transmit streams (FMT = 00h). The default value for this bit is 0.

7 ‡

enab_unfair

RW

Enable asynchronous priority requests. OHCI-Lynx

compatible. Setting bit 7 to 1 enables the link to

respond to requests with priority arbitration. It is recommended that this bit be set to 1. The default value
for this bit is 0.

6

RSVD

R

This bit is not assigned in the PCI7x21/PCI7x11 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).

5−3

RSVD

R

Reserved. Bits 5−3 return 0s when read.

2 ‡

RSVD

R

Reserved. Bit 2 returns 0 when read.

1 ‡

enab_accel

RW

Enable acceleration enhancements. OHCI-Lynx

compatible. When bit 1 is set to 1, 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 1. The default value
for this bit is 0.

0

RSVD

R

Reserved. Bit 0 returns 0 when read.

‡ This bit is cleared only by the assertion of GRST.

7.25 Subsystem Access Register

Write access to the subsystem access register updates the subsystem identification registers identically to
OHCI-Lynx

. The system ID value written to this register may also be read back from this register. See Table 7−22

for a complete description of the register contents.

Bit

31

30

29

28

27

26

25

24

23

22

21

20

19

18

17

16

Name

Subsystem access

Type

RW

RW

RW

RW

RW

RW

RW

RW

RW

RW

RW

RW

RW

RW

RW

RW

Default

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

Bit

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

Name

Subsystem access

Type

RW

RW

RW

RW

RW

RW

RW

RW

RW

RW

RW

RW

RW

RW

RW

RW

Default

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

Register:

Subsystem access

Offset:

F8h

Type:

Read/Write

Default:

0000 0000h

Table 7−22. Subsystem Access Register Description

BIT

FIELD NAME

TYPE

DESCRIPTION

31−16 ‡

SUBDEV_ID

RW

Subsystem device ID alias. This field indicates the subsystem device ID.

15−0 ‡

SUBVEN_ID

RW

Subsystem vendor ID alias. This field indicates the subsystem vendor ID.

‡ These bits are cleared only by the assertion of GRST.