Technical Reference: Kernel and Subsystems, Volume 1

d_complete Kernel Service

Purpose

Cleans up after a direct memory access (DMA) transfer.

Syntax

#include <sys/types.h>
#include <sys/errno.h>
#include <sys/dma.h>
#include <sys/xmem.h>

int d_complete (channel_id, flags, baddr, count, dp, daddr) int channel_id; int flags; caddr_t baddr; size_t count; struct xmem * dp; caddr_t daddr;

Parameters

channel_id	Specifies the DMA channel identifier returned by the d_init service.
flags	Describes the DMA transfer. The /usr/include/dma.h file describes these flags.
baddr	Designates the address of the memory buffer.
count	Specifies the length of the transfer in bytes.
dp	Specifies the address of the cross-memory descriptor.
daddr	Designates the address used to program the DMA master. A value of null is specified for DMA slaves.

Description

The d_complete kernel service completes the processing of a DMA transfer. It also indicates any DMA error detected by the system hardware. The d_complete service must be called after each DMA transfer.

The d_complete service performs machine-dependent processing, which entails:

Flushing system DMA buffers
Making the DMA buffer accessible to the processor
Note

When calling the d_master service several times for one or more of the same pages of memory, the corresponding number of d_complete calls must be made to reveal successfully the page or pages involved in the DMA transfers. Pages are not hidden from the processor during the DMA mapping if the DMA_WRITE_ONLY flag is specified on the call to the d_master service.

"Understanding Direct Memory Access (DMA) Transfers" in AIX 5L Version 5.2 Kernel Extensions and Device Support Programming Concepts further describes DMA transfers.

Note

The d_complete kernel service is not supported on the 64-bit kernel.

Execution Environment

The d_complete kernel service can be called from either the process or interrupt environment.

Return Values

DMA_SUCC	Indicates a successful completion.
DMA_INVALID	Indicates an operation that is not valid. A load or store that was not valid was performed to the I/O bus.
DMA_LIMIT	Indicates a limit check. A load or store to the I/O bus occurred that was not sufficiently authorized to access the I/O bus address.
DMA_NO_RESPONSE	Indicates no response. No device responded to the I/O bus access.
DMA_CONFLICT	Indicates an address conflict. A daddr parameter was specified to the d_master service for a system memory transfer, where this transfer conflicts with the bus memory address of an I/O bus device.
DMA_AUTHORITY	Indicates an authority error. A protection exception occurred while accessing an I/O bus memory address.
DMA_PAGE_FAULT	Indicates a page fault. A reference was made to a page not currently located in system memory.
DMA_BAD_ADDR	Indicates an address that is not valid. A bus address that is not valid or was unsupported was used. A daddr parameter that was not valid was specified to the d_master service.
DMA_CHECK	Indicates a channel check. A channel check was generated during the bus cycle. This typically occurs when a device detects a data parity error.
DMA_DATA	Indicates a system-detected data parity error.
DMA_ADDRESS	Indicates a system-detected address parity error.
DMA_EXTRA	Indicates an extra request. This typically occurs when the count parameter was specified incorrectly to the d_slave service.
DMA_SYSTEM	Indicates a system error. The system detected an internal error in system hardware. This is typically a parity error on an internal bus or register.

Related Information

The d_init kernel service, d_master kernel service, d_slave kernel service.

I/O Kernel Services and Understanding Direct Memory Access (DMA) Transfers in AIX 5L Version 5.2 Kernel Extensions and Device Support Programming Concepts.