Register: 0x0C

Cache Line Size

Read/Write

7

0

CLS

0

0

0

0

0

0

0

0

 

 

 

 

 

 

CLSCache Line Size[7:0]

This register specifies the system cache line size in units of 32-bit words. Cache mode is enabled and disabled by the Cache Line Size Enable (CLSE) bit, bit 7 in the DMA Control (DCNTL) register. Setting this bit causes the LSI53C810A to align to cache line boundaries before allowing any bursting, except during MMOVs in which the read and write addresses are Burst Size boundary misaligned. For more information see Section 3.2.1, “Support for PCI Cache Line Size Register,” page 3-3.

Register: 0x0D

Latency Timer

Read/Write

7

0

LT

0

0

0

0

0

0

0

0

 

 

 

 

 

 

LTLatency Timer[7:0]

The Latency Timer register specifies, in units of PCI bus clocks, the value of the Latency Timer for this PCI bus master. The LSI53C810A supports this timer. All eight bits are writable, allowing latency values of 0–255 PCI clocks. Use the following equation to calculate an optimum latency value for the LSI53C810A:

Latency = 2 + (Burst Size * (typical wait states +1)) Values greater than optimum are also acceptable.

3-16

PCI Functional Description

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Image 58
LSI 53C810A technical manual Register 0x0C, Register 0x0D, Cache Line Size Read/Write, CLSCache Line Size70