PCI7421 datasheet(264/298 Pages) TI

264 / 298 page

12−10

12.15 Maximum Latency Register

The maximum latency register contains the maximum latency value for the SD host controller core.

Bit

Name

Maximum latency

Type

Default

Maximum latency

Offset:

3Fh

Type:

Read/Update

Default:

04h

Table 12−10. Maximum Latency Register Description

BIT

FIELD NAME

TYPE

DESCRIPTION

7−0

MAX_LAT

Maximum latency. The contents of this field may be used by host BIOS to assign an arbitration priority level

to the SD host controller. The default for this register indicates that the SD host controller may need to

access the PCI bus as often as every 0.25

µs; thus, an extremely high priority level is requested. The

contents of this field may also be loaded through the serial EEPROM.

12.16 Slot Information Register

This read-only register contains information on the number of SD sockets implemented and the base address

Registers used.

Bit

Name

Slot information

Type

Default

Maximum latency

Offset:

40h

Type:

Read/Update

Default:

X0h

Table 12−11. Maximum Latency Register Description

BIT

FIELD NAME

TYPE

DESCRIPTION

RSVD

Reserved. This bit returns 0 when read.

6−4

NUMBER_SLOTS

Number of slots. This field indicates the number of SD sockets supported by the SD host controller.

Since the controller supports three SD sockets, this field returns 010 when read.

RSVD

Reserved. This bit returns 0 when read.

2−0

FIRST_BAR

First base address register number. This field is hardwired to 000b to indicate that the first BAR used

for the SD host standard registers is BAR0.

PCI7421 Datasheet(PDF) 264 Page - Texas Instruments

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