svn commit: r285270 - head/sys/sys
Andrew Turner
andrew at fubar.geek.nz
Wed Jul 8 13:58:54 UTC 2015
On Wed, 8 Jul 2015 13:53:00 +0000 (UTC)
Zbigniew Bodek <zbb at 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();
Should this be a dmb or dsb? mb() is implemented as the former on
ARMv7, and as the equivalent using mcr on ARMv6. Only on ARMv4 and
ARMv5 is it a dsb.
Andrew
More information about the svn-src-all
mailing list