On Jun 11, 2010, at 10:37 AM, Scott Long wrote:
>
> I'm not clear why you even need bounce buffers for RX. The chip supports
> 64bit addresses with no boundary or alignment restrictions.
As per:
/*
* All controllers that are not 5755 or higher have 4GB
* boundary DMA bug.
* Whenever an address crosses a multiple of the 4GB boundary
* (including 4GB, 8Gb, 12Gb, etc.) and makes the transition
* from 0xX_FFFF_FFFF to 0x(X+1)_0000_0000 an internal DMA
* state machine will lockup and cause the device to hang.
*/
if (BGE_IS_5755_PLUS(sc) == 0)
sc->bge_flags |= BGE_FLAG_4G_BNDRY_BUG;
and:
lowaddr = BUS_SPACE_MAXADDR;
if ((sc->bge_flags & BGE_FLAG_40BIT_BUG) != 0)
lowaddr = BGE_DMA_MAXADDR;
if ((sc->bge_flags & BGE_FLAG_4G_BNDRY_BUG) != 0)
lowaddr = BUS_SPACE_MAXADDR_32BIT;
/*
* Allocate the parent bus DMA tag appropriate for PCI.
*/
error = bus_dma_tag_create(bus_get_dma_tag(sc->bge_dev),
1, 0, lowaddr, BUS_SPACE_MAXADDR, NULL,
NULL, BUS_SPACE_MAXSIZE_32BIT, 0, BUS_SPACE_MAXSIZE_32BIT,
0, NULL, NULL, &sc->bge_cdata.bge_parent_tag);
--
Marcel Moolenaar
xcl...@mac.com
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