PCI7421 datasheet(263/298 Pages) TI

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12−9

12.13 Interrupt Pin Register

This register decodes the interrupt select inputs and returns the proper interrupt value based on Table 12−8,

indicating that the SD host controller uses an interrupt. If one of the USE_INTx terminals is asserted, the interrupt

select bits are ignored, and this register returns the interrupt value for the highest priority USE_INTx terminal that is

asserted. If bit 28, the tie-all bit (TIEALL), in the system control register (PCI offset 80h, see Section 4.29) is set to

1, then the PCI7x21/PCI7x11 controller asserts the USE_INTA input to the SD host controller core. If bit 28 (TIEALL)

in the system control register (PCI offset 80h, see Section 4.29) is set to 0, then none of the USE_INTx inputs are

asserted and the interrupt for the SD host controller function is selected by the INT_SEL bits in the SD host general

control register.

Bit

Name

Interrupt pin

Type

Default

Interrupt pin

Offset:

3Dh

Type:

Read-only

Default:

0Xh

Table 12−8. PCI Interrupt Pin Register

INT_SEL BITS

USE_INTA

INTPIN

01h (INTA)

02h (INTB)

03h (INTC)

04h (INTD)

01h (INTA)

12.14 Minimum Grant Register

The minimum grant register contains the minimum grant value for the SD host controller core.

Bit

Name

Minimum grant

Type

Default

Minimum grant

Offset:

3Eh

Type:

Read/Update

Default:

07h

Table 12−9. Minimum Grant Register Description

BIT

FIELD NAME

TYPE

DESCRIPTION

7−0

MIN_GNT

Minimum grant. The contents of this field may be used by host BIOS to assign a latency timer register value

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

sustain burst transfers for nearly 64

µs and thus request a large value be programmed in bits 15−8 of the

PCI7x21/PCI7x11 latency timer and class cache line size register at offset 0Ch in the PCI configuration

space (see Section 12.6).

PCI7421 Datasheet(PDF) 263 Page - Texas Instruments

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