Problem getting quadword aligned DMA address

Question

Hello,
I am writing a block device driver under Solaris 8 Ultra 80 SPARC. My device needs quadword aligned DMA addresses. How can I get this from the DDI calls? Currently thsi is what i am doing:
1. Settting up ddi_dma_attr_t structure as
static ddi_dma_aatr_t mydma_attr
DMA_ATTR_V0,
0x00000000,
0xffffffff,
0x00ffffff,
0x8 // quad word alignment
0x1,
0x8,
0xffffffff
0xffffffff
max_desc //s/g list
512,
0,
2. Use ddi_dma_alloc_handle wihich among other things takes this mydma_attr structre as its parameters.
3. Thsi provides a dma_handle which is used by ddi_dma_buf_bind_handle() which fills in the cookie cookie_dma of type dma_cookie_t.
As per the documentation this cookie_dma.dmac_laddress shloud be used to program 64 bit DMA engine. But this is not working.
Should I be using ddi_dma_addr_bind() call instead of ddi_dma_buf_bind_handle? What is the difference?
Thanks
Madhura

Answer 1

The difference between ddi_dma_buf_bind_handle(9F) and
ddi_dma_addr_bind_handle(9F) is that the former is used to bind a DMA handle to a system buffer and the latter is used to bind a DMA handle to a virtual address, generally allocated by ddi_dma_mem_alloc(). If you are performing DMA to/from a system buffer, ddi_dma_buf_bind_handle(9F) is the correct function to use.
If the DMA is not working, it is likely that the attributes are not set correctly.