Intel
®
81341 and 81342—Application DMA Unit
Intel
®
81341 and 81342 I/O Processors
Developer’s Manual
December 2007
526
Order Number: 315037-002US
5.16.6
ADMA Descriptor Control Register x — ADCRx
The ADMA Descriptor Control Register contains control values for data transfer on a
per-chain descriptor basis. This read-only register is loaded when a basic or full chain
descriptor is read from memory. These values may vary from chain descriptor to chain
shows the definition of the ADMA Descriptor Control
Register.
Table 321. ADMA Descriptor Control Register x — ADCRx (Sheet 1 of 3)
Bit
Default
Description
31
0
2
No Snoop Enable -- When set, the 81341 and 81342 sets the No Snoop (NS) attribute for requests
initiated on the host I/O interface that are associated with this transfer.
30
0
2
Relaxed Ordering Enable -- When set, the 81341 and 81342 sets the Relaxed Ordering (RO) attribute for
requests initiated on the host I/O interface that are associated with this transfer.
29:28
00
2
Reserved
27
0
2
Reserved
26:20
0000000
2
Reserved
19
0
2
P Transfer Disable - When set and P+Q Transfer (or a P+Q Update Transfer or a P+Q Zero Result Buffer
Error Check) is enabled (i.e., bit 18 (or bit 16 or bit 18 and bit 7) of the ADCRx is set), this bit disables
the transfer of P to the P_Destination. Q is generated and transferred to the Q_Destination.
Note:
The hardware requires a properly aligned (16-byte address boundary) P_Destination Address
be provided for proper operation even when the P transfer is disabled. When P transfer is
disabled the hardware still performs the appropriate P operation, but simply does not write the
result to the P_Destination Address.
18
0
2
P+Q Transfer Enable - When set, the ADMA generates both P and Q of the P+Q RAID6 algorithm on
multiple source data streams (see
Section 5.7.3, “XOR Operation with P+Q RAID-6” on page 494
) and
transfer them to the P_Destination and Q_Destination, respectively.
17
0
2
Dual XOR Enable - When set, the ADMA interprets this descriptor as a Dual XOR operation.
The Source Selection Field (bits 6:3) must be programmed to 0011b when this enable bit is set.
Note:
The Dual XOR operation cannot be combined with any other ADMA operation.
16
0
2
P+Q Update Transfer Enable - When set, the ADMA interprets this descriptor as a P+Q Update transfer
operation.
The Source Selection Field (bits 6:3) must be programmed to 0011b when this enable bit is set.
Note:
The P+Q Update transfer operation cannot be combined with any other ADMA operation.
15
0
2
Reserved
14
0
2
Reserved
13
0
2
Endian Swap Enable - When set, the ADMA performs a 4 byte Endian Swap during a data transfers
between the Host I/O interface and the Local Memory. The Endian assumptions for the Host and Local
Memory are controlled by the Endian Mode Selector (bit 19 of the ACCR).
12
0
2
Status Write Back Enable - At the end of a transfer, when this bit is set, the ADMA writes back the Byte
Count Word of the descriptor pointed to by the ADAR.
11
0
2
CRC Seed Fetch Disable -- When set and the CRC Generation Enable is set (bit 9 of the ADCR), the
ADMA uses the byte-wise flipped and inverted version of the CRC value located at the CRC Address
(CARMD) as the seed for the current CRC operation. When clear and the CRC Generation Enable is set
(bit 9 of the ADCR), the ADMA uses the value located at the CRC Address (CARMD) as the seed for the
current CRC operation.
Host
IOP
Attributes
Attributes
28
24
20
16
12
8
4
0
31
ro
na
ro
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
ro
na
ro
na
ro
na
ro
na
rv
na
rv
na
ro
na
ro
na
ro
na
ro
na
ro
na
ro
na
ro
na
ro
na
ro
na
ro
na
ro
na
ro
na
ro
na
ro
na
Attribute Legend:
RV = Reserved
PR = Preserved
RS = Read/Set
RW = Read/Write
RC = Read Clear
RO = Read Only
NA = Not Accessible
Channel #
0
1
2
Internal bus address offset
0028H
0228H
0428H