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DMA Controller
Copyright © 12/13/06 Marvell
CONFIDENTIAL
Doc. No. MV-TBD-00 Rev. A
December 13, 2006
Document Classification: Proprietary Information
Page 337
Not approved by Document Control. For review only.
DALGN must be updated before setting DCSR[Run] and then must not be altered until the channel stops.
11.4.10
DMA Programmed I/O Control Status Register (DPCSR)
DPCSR, defined in
, is used for activating and monitoring posted writes and split reads on the system
bus when software uses programmed I/O (PIO) instructions to access the peripheral address domain via the
DMA bridge.
Setting DPCSR[BRGSPLIT] activates the following DMA behavior:
•
If the PIO transaction is a read from a peripheral address domain, the DMA split responds to the read
instruction. The DMA bridge will release the system bus, then use micro-coded instructions to read data
from the peripheral bus. Once the read completes across the peripheral bus, the DMAC completes the split
transaction by re-capturing the system bus and completing the PIO read transaction. The core stalls until the
read is returned because this is programmed IO. Any PIO transactions (reads or writes) that occurs while the
current PIO read transaction is between the split response and the split completion are retried.
•
If the PIO transaction is a write instruction to a peripheral address domain, the DMA posts the write
instruction. The DMA bridge indicates to the system bus that the PIO write is complete and then release the
system bus. The actual write transaction is then sent across the peripheral bus using microcoded instructions.
If software requires that a write complete on the peripheral bus before continuing, then software must write
the address, then immediately read the same address, which guarantees that the address has been updated
before allowing the core to continue execution.
Clearing DPCSR[BRGSPLIT] deactivates the posted write and split response behavior. A write transaction on
the system bus is completed only after the write is sent across the peripheral bus. The targeted address location is
guaranteed to be updated by the time the transaction completes on the system bus. A read transaction on the
system bus is completed only after the DMA bridge receives the data from across the peripheral bus. There are
no split responses, split completions, or retries in this mode.
Table 11-17. DALGN Bit Definitions
Physical Address
0x4000_00A0
DALGN
DMA Controller
User
Settings
Bit
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
8
7
6
5
4
3
2
1
0
DA
L
G
N31
DA
L
G
N30
DA
L
G
N29
DA
L
G
N28
DA
L
G
N27
DA
L
G
N26
DA
L
G
N25
DA
L
G
N24
DA
L
G
N23
DA
L
G
N22
DA
L
G
N21
DA
L
G
N20
DA
L
G
N19
DA
L
G
N18
DA
L
G
N17
DA
L
G
N16
DA
L
G
N15
DA
L
G
N14
DA
L
G
N13
DA
L
G
N12
DALGN1
1
DA
L
G
N10
DALGN9
DALGN8
DALGN7
DALGN6
DALGN5
DALGN4
DALGN3
DALGN2
DALGN1
DALGN0
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Bits
Access
Name
Description
31:0
R/W
DALGNx
Alignment control for channel x
0 = Source and target addresses of channel x are default aligned (internal
peripherals default to 4 byte alignment; external bus addresses
default to 8 byte alignment)
1 = Source and target addresses of channel x are as defined by user
(byte aligned)