HS_Media independent interface (MII)
RM0082
522/844
Doc ID 018672 Rev 1
●
FB
Setting this bit, the AHB Master interface performs only fixed bursts transfers (SINGLE,
INCR4, INCR8 or INCR16). In contrast, the AHB will use SINGLE and INCR burst only.
●
PR
This 2 bit field indicates the ratio of the RxDMA requests given priority over TxDMA
request, according to encoding below:
●
PBL
This 6 bit field states the maximum number of beats to be transferred in one DMA
transmission. Each time DMA starts a burst transfer on the host bus, it will always
attempt to burst as specified by PBL value. Valid values for PBL are 1, 2, 4, 8, 16 and
32, and any other value will result in undefined behavior.
●
DSL
This 5 bit field specifies the number of Word/Dword/Long (depending on 32(64/128 bit
bus) to skip between two unchained descriptors. If DSL is zero (5'h0, default) then the
descriptor table is taken as contiguous by the DMA in ring mode.
●
DA
This bit allows the selection of the DMA arbitration scheme, according to encoding
below:
Table 425.
Bus mode register bit assignments
Bit
Name
Reset Value
Type
Description
[31:17]
Reserved
-
RO
Read: undefined
[16]
1’h0
RW
Fixed Burst
[15:14]
2’h0
RW
Rx:Tx Priority Ratio.
[13:08]
6’h0
RW
Programmable Burst Length.
[07]
Reserved
-
RO
Read: undefined
[06:02]
5’h0
RW
Descriptor Skip Length.
[01]
1’h0
RW
DMA Arbitration Scheme
[00]
1’h0
RW
Software Reset
VALUE
Rx:Tx RATIO
2‘b00
1:1
2‘b01
2:1
2‘b10
3:1
2‘b11
4:1