tran_dmafree() Entry Point

The tran_dmafree(9E) entry point is the HBA driver function that deallocates DMA resources allocated for a scsi_pkt(9S) structure. The tran_dmafree() entry point is called when the target driver calls scsi_dmafree(9F).

tran_dmafree() must free only DMA resources allocated for a scsi_pkt(9S) structure, not the scsi_pkt(9S) itself. Freeing the DMA resources implicitly performs a DMA synchronization.

The scsi_pkt(9S) will be freed in a separate request to tran_destroy_pkt(9E). Because tran_destroy_pkt() must also free DMA resources, the HBA driver must keep accurate note of whether scsi_pkt() structures have DMA resources allocated.

Example 15–7 HBA Driver tran_dmafree(9E) Entry Point

static void
isp_scsi_dmafree(
    struct scsi_address    *ap,
    struct scsi_pkt        *pkt)
{
    struct isp_cmd         *sp = (struct isp_cmd *)pkt->pkt_ha_private;

    if (sp->cmd_flags & CFLAG_DMAVALID) {
           sp->cmd_flags &= ~CFLAG_DMAVALID;
           (void)ddi_dma_unbind_handle(sp->cmd_dmahandle);
           ddi_dma_free_handle(&sp->cmd_dmahandle);
           sp->cmd_dmahandle = NULL;
    }
}