![](http://datasheet.mmic.net.cn/330000/PCI4515_datasheet_16443874/PCI4515_163.png)
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8.16 Host Controller Control Register
The host controller control set/clear register pair provides flags for controlling the PCI4515 controller. See Table 811
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
Host controller control
Type
RSU
RSC
RSC
R
R
R
R
R
R
RSC
R
R
RSC
RSC
RSC
RSCU
Default
0
X
0
0
0
0
0
0
1
0
0
0
0
X
0
0
Bit
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Name
Host controller control
Type
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
Default
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Register:
Offset:
Host controller control
50h
set register
54h
clear register
Read/Set/Clear/Update, Read/Set/Clear, Read/Clear, Read-only
X08X 0000h
Type:
Default:
Table 811. Host Controller Control Register Description
BIT
FIELD NAME
TYPE
DESCRIPTION
31
BIBimage Valid
RSU
When bit 31 is set to 1, the PCI4515 physical response unit is enabled to respond to block read
requests to host configuration ROM and to the mechanism for atomically updating configuration
ROM. Software creates a valid image of the bus_info_block in host configuration ROM before
setting this bit.
When this bit is cleared, the PCI4515 controller returns ack_type_error on block read requests
to host configuration ROM. Also, when this bit is cleared and a 1394 bus reset occurs, the
configuration ROM mapping register at OHCI offset 34h (see Section 8.12), configuration ROM
header register at OHCI offset 18h (see Section 8.7), and bus options register at OHCI offset 20h
(see Section 8.9) are not updated.
Software can set this bit only when bit 17 (linkEnable) is 0. Once bit 31 is set to 1, it can be cleared
by a system (hardware) reset, a software reset, or if a fetch error occurs when the PCI4515
controller loads bus_info_block registers from host memory.
30
noByteSwapData
RSC
Bit 30 controls whether physical accesses to locations outside the PCI4515 controller itself, as
well as any other DMA data accesses are byte swapped.
29
AckTardyEnable
RSC
Bit 29 controls the acknowledgement of ack_tardy. When bit 29 is set to 1, ack_tardy may be
returned as an acknowledgment to accesses from the 1394 bus to the PCI4515 controller,
including accesses to the bus_info_block. The PCI4515 controller returns ack_tardy to all other
asynchronous packets addressed to the PCI4515 node. When the PCI4515 controller sends
ack_tardy, bit 27 (ack_tardy) in the interrupt event register at OHCI offset 80h/84h (see
Section 8.21) is set to 1 to indicate the attempted asynchronous access.
Software ensures that bit 27 (ack_tardy) in the interrupt event register is 0. Software also unmasks
wake-up interrupt events such as bit 19 (phy) and bit 27 (ack_tardy) in the interrupt event register
before placing the PCI4515 controller into the D1 power mode.
Software must not set this bit if the PCI4515 node is the 1394 bus manager.
2824
RSVD
R
Reserved. Bits 2824 return 0s when read.
23
programPhyEnable
R
Bit 23 informs upper-level software that lower-level software has consistently configured the IEEE
1394a-2000 enhancements in the link and PHY layers. When this bit is 1, generic software such
as the OHCI driver is responsible for configuring IEEE 1394a-2000 enhancements in the PHY
layer and bit 22 (aPhyEnhanceEnable). When this bit is 0, the generic software may not modify
the IEEE 1394a-2000 enhancements in the PHY layer and cannot interpret the setting of bit 22
(aPhyEnhanceEnable). This bit is initialized from serial EEPROM. This bit defaults to 1.
This bit is cleared only by the assertion of GRST.