Date: Wed, 8 Jul 2015 07:47:42 -0700 From: Adrian Chadd <adrian.chadd@gmail.com> To: Ian Lepore <ian@freebsd.org> Cc: Zbigniew Bodek <zbb@freebsd.org>, "src-committers@freebsd.org" <src-committers@freebsd.org>, "svn-src-all@freebsd.org" <svn-src-all@freebsd.org>, "svn-src-head@freebsd.org" <svn-src-head@freebsd.org> Subject: Re: svn commit: r285270 - head/sys/sys Message-ID: <CAJ-Vmo=V5J98J=tvmtgnuVtsR_DEjHs=%2BK1=V5WRcPJWZDkdPg@mail.gmail.com> In-Reply-To: <1436366547.1334.81.camel@freebsd.org> References: <201507081353.t68Dr0up028388@repo.freebsd.org> <CAJ-Vmoku0OzPU=v6X3jb04EQqXXrgSFC9=iFxO8JYCri=XX4XQ@mail.gmail.com> <1436366547.1334.81.camel@freebsd.org>
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On 8 July 2015 at 07:42, Ian Lepore <ian@freebsd.org> wrote: > On Wed, 2015-07-08 at 07:30 -0700, Adrian Chadd wrote: >> Why is this implemented in sys/sys/bus_dma.h, rather than in a machdep header? >> >> > > Indeed, this stuff is a mess that really needs to be cleaned up. The > pre-existing assumption that MI functions don't need to be called, just > because one of the parameters of that function has some value that has a > special meaning on one platform, is purely x86-MD code in an MI header > file. This change just complicates the existing mess. +1 (So who's going to do it? I'm already taken.) -a >> -a >> >> >> On 8 July 2015 at 06:53, Zbigniew Bodek <zbb@freebsd.org> wrote: >> > Author: zbb >> > Date: Wed Jul 8 13:52:59 2015 >> > New Revision: 285270 >> > URL: https://svnweb.freebsd.org/changeset/base/285270 >> > >> > Log: >> > Add memory barrier to bus_dmamap_sync() >> > >> > On platforms which are fully IO-coherent, the map might be null. >> > We need to guarantee that all data is observable after the >> > sync operation is called. Add a memory barrier to ensure that on ARM. >> > >> > Reviewed by: andrew, kib >> > Obtained from: Semihalf >> > Sponsored by: The FreeBSD Foundation >> > Differential Revision: https://reviews.freebsd.org/D3012 >> > >> > Modified: >> > head/sys/sys/bus_dma.h >> > >> > Modified: head/sys/sys/bus_dma.h >> > ============================================================================== >> > --- head/sys/sys/bus_dma.h Wed Jul 8 13:19:13 2015 (r285269) >> > +++ head/sys/sys/bus_dma.h Wed Jul 8 13:52:59 2015 (r285270) >> > @@ -282,13 +282,25 @@ int bus_dmamem_alloc(bus_dma_tag_t dmat, >> > void bus_dmamem_free(bus_dma_tag_t dmat, void *vaddr, bus_dmamap_t map); >> > >> > /* >> > - * Perform a synchronization operation on the given map. >> > + * Perform a synchronization operation on the given map. If the map >> > + * is NULL we have a fully IO-coherent system. On every ARM architecture >> > + * there must be a memory barrier placed to ensure that all data >> > + * accesses are visible before going any further. >> > */ >> > void _bus_dmamap_sync(bus_dma_tag_t, bus_dmamap_t, bus_dmasync_op_t); >> > +#if defined(__arm__) >> > + #define __BUS_DMAMAP_SYNC_DEFAULT mb(); >> > +#elif defined(__aarch64__) >> > + #define __BUS_DMAMAP_SYNC_DEFAULT dmb(sy); >> > +#else >> > + #define __BUS_DMAMAP_SYNC_DEFAULT {} >> > +#endif >> > #define bus_dmamap_sync(dmat, dmamap, op) \ >> > do { \ >> > if ((dmamap) != NULL) \ >> > _bus_dmamap_sync(dmat, dmamap, op); \ >> > + else \ >> > + __BUS_DMAMAP_SYNC_DEFAULT \ >> > } while (0) >> > >> > /* >> > >> > >
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