ddi_dma_nextcookie(9F)

NAME

ddi_dma_nextcookie − retrieve subsequent DMA cookie

SYNOPSIS

#include <sys/ddi.h>
#include <sys/sunddi.h>

void ddi_dma_nextcookie(ddi_dma_handle_t handle, ddi_dma_cookie_t ∗cookiep);

ARGUMENTS

handle The handle previously allocated by a call to ddi_dma_alloc_handle(9F).

cookiep A pointer to a ddi_dma_cookie(9S) structure.

INTERFACE LEVEL

Solaris DDI specific (Solaris DDI).

DESCRIPTION

ddi_dma_nextcookie() retrieves subsequent DMA cookies for a DMA object. ddi_dma_nextcookie() fills in the ddi_dma_cookie(9S) structure pointed to by cookiep. The ddi_dma_cookie(9S) structure must be allocated prior to calling ddi_dma_nextcookie().

The DMA cookie count returned by ddi_dma_buf_bind_handle(9F), ddi_dma_addr_bind_handle(9F), or ddi_dma_getwin(9F) indicates the number of DMA cookies a DMA object consists of. If the resulting cookie count, N, is larger than 1, ddi_dma_nextcookie() must be called N-1 times to retrieve all DMA cookies.

CONTEXT

ddi_dma_nextcookie() can be called from user, kernel, or interrupt context.

EXAMPLES

This example demonstrates the use of ddi_dma_nextcookie() to process a scatter-gather list of I/O requests.

/∗ setup scatter-gather list with multiple DMA cookies ∗/
ddi_dma_cookie_tdmacookie;
uint_tccount;
...
status = ddi_dma_buf_bind_handle(handle, bp, DDI_DMA_READ,
NULL, NULL, &dmacookie, &ccount);

if (status == DDI_DMA_MAPPED) {
/∗ program DMA engine with first cookie ∗/

while (--ccount > 0) {
ddi_dma_nextcookie(handle, &dmacookie);
/∗ program DMA engine with next cookie ∗/
}
}
...

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