MB87P2020 Datasheet, PDF (121/356 Pages) Fujitsu Component Limited. – Colour LCD/CRT/TV Controller

DIPA Direct/Indirect Physical Access
2 Configuration Registers
2.1 Register List
Configuration of DIPA internal registers is needed for SDRAM arbitration priority information and to con-
trol IPAs FIFO buffering. This influences system performance and bandwidth balance only.
Table 2-1: DIPA performance adjustment registers
Register
DIPACTRL_PDPA
DIPACTRL_PIPA
DIPAIF_IFMIN
Address
0x4200
0x4200
0x4204
DIPAIF_IFMAX 0x4204
DIPAOF_OFMIN 0x4208
DIPAOF_OFMAX 0x4208
Bits
[18:16]
[2:0]
[6:0]
[22:16]
[6:0]
[22:16]
Function
DPA arbitration priority [0...7]
IPA arbitration priority [0...7]
Minimum block size for data transfer to the
video RAM (>= 2)
Maximum block size for data transfer to the
video RAM (>= IPAIF_MIN)
Minimum block size for data transfer from
the video RAM (>= 1)
Maximum block size for data transfer to the
video RAM (>= IPAOF_MIN)
Initial
0x0
0x0
0x02
0x02
0x01
0x01
Initial values (reset-state) for IPA configuration are not default values an some of them restricted for oper-
ation. An configuration of block sizes is required before IPA operation is possible.
2.2 Recommended Settings
Figure 2-1 shows the relationship between IPA settings for input or output FIFO and the current FIFO load.
If the load is smaller than IFMIN or OFMIN no data transfer is performed. In the load range between
IFMIN/OFMIN and IFMAX/OFMAX a single transfer with at least IFMIN/OFMIN data words is triggered.
Above IFMAX/OFMAX FIFO load the transfer is packetized into packages of IFMAX/OFMAX size.
FIFOSIZE
IFMAX/OFMAX
packetized transfer with
IFMAX/OFMAX size
transfer possible
IFMIN/OFMIN
no transfer
0
Figure 2-1: DIPA settings for input and output FIFO
The configuration with respect to system behaviour depends on the bandwidth reserve for video RAM ac-
cess (transfer rate and core clock dependent). Normally GPU and VIC have highest access arbitration pri-
ority due to the fact that this are real-time applications and its bandwidth violations would lead to data loss
(drop of display or video data may be the result of wrong configuration).
Configuration Registers
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