ddi_iomin(9F)

NAME

     ddi_iomin - find minimum alignment and transfer size for DMA

SYNOPSIS

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

     int ddi_iomin(dev_info_t *dip, int initial, int streaming);

INTERFACE LEVEL

     Solaris DDI specific (Solaris DDI).

PARAMETERS

     dip   A pointer to the device's dev_info structure.

     initial
           The initial minimum DMA transfer size in  bytes.  This
           may  be  zero or an appropriate dlim_minxfer value for
           device's       ddi_dma_lim       structure        (see
           ddi_dma_lim_sparc(9S)  or  ddi_dma_lim_x86(9S)).  This
           value must be a power of two.

     streaming
           This  argument,  if  non-zero,  indicates   that   the
           returned  value  should  be  modified  to  account for
           streaming mode accesses  (see  ddi_dma_req(9S)  for  a
           discussion  of  streaming  versus non-streaming access
           mode).

DESCRIPTION

     ddi_iomin(), finds out the minimum DMA transfer size for the
     device pointed to by dip. This provides a mechanism by which
     a driver can determine the effects of underlying  caches  as
     well as intervening bus adapters on the granularity of a DMA
     transfer.

RETURN VALUES

     ddi_iomin() returns the minimum DMA transfer  size  for  the
     calling  device,  or  it returns zero,  which means that you
     cannot get there from here.

CONTEXT

     This function can be called from user or interrupt context.

SEE ALSO

     ddi_dma_devalign(9F),  ddi_dma_setup(9F),  ddi_dma_sync(9F),
     ddi_dma_lim_sparc(9S), ddi_dma_lim_x86(9S), ddi_dma_req(9S)

     Writing Device Drivers