Date: Fri, 11 Jun 2010 10:44:57 -0700 From: Marcel Moolenaar <xcllnt@mac.com> To: Scott Long <scottl@samsco.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org, John Baldwin <jhb@freebsd.org> Subject: Re: svn commit: r209026 - in head/sys/ia64: ia64 include Message-ID: <53158C9B-C9E1-4C47-B361-83C76181721A@mac.com> In-Reply-To: <028BA7D4-90C8-4D2D-B9A5-C1C3CF9B6D7D@samsco.org> References: <201006110300.o5B30X9q045387@svn.freebsd.org> <201006110751.40735.jhb@freebsd.org> <853068F6-D736-4DA3-859F-D946D096843D@samsco.org> <19B0DF11-5998-40F5-8095-8D2521B1C597@mac.com> <EE4B5C07-194D-4408-B0A1-BA25BE39468F@samsco.org> <291D17F7-F387-4A13-8ED9-2898A9F7E018@mac.com> <028BA7D4-90C8-4D2D-B9A5-C1C3CF9B6D7D@samsco.org>
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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
xcllnt@mac.com
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