SVR5

dma_get_best_mode(D3)

dma_get_best_mode -- determine best transfer mode for DMA command

Synopsis

   #include <sys/types.h>
   #include <sys/dma.h>
   #include <sys/ddi.h>

   uchar_t dma_get_best_mode(struct dma_cb *dmacbptr);

Description

dma_get_best_mode determines the best DMA transfer mode to use with the DMA operation specified in the command block whose address is given by dmacbptr. This function is used for ISA, EISA, and MCA DMA channels.

Arguments

dmacbptr: Pointer to a DMA command block.

Return values

dma_get_best_mode returns a value that specifies the transfer mode. This value should be used to set the ``cycles'' field of the dma_cb(D4) structure.

Usage

Prior to the call to dma_get_best_mode, all fields of the command block should have been initialized except for ``cycles''. The ``cycles'' field should be initialized using the return value from dma_get_best_mode.

Context and synchronization

All contexts.

Hardware applicability

PC-AT compatible platforms with ISA, EISA, or MCA buses

Version applicability

ddi: 1, 2, 3, 4, 5, 5mp, 6, 6mp, 7, 7mp, 7.1, 7.1mp, 8, 8mp

Future directions

This interface is expected to be replaced or modified in a future release.

References

dma_cb(D4)

``DMA'' in HDK Technical Reference