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Add memory barrier to bus_dmamap_sync()

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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
This commit is contained in:
Zbigniew Bodek 2015-07-08 13:52:59 +00:00
parent 69d11def74
commit 4981c60e07
1 changed files with 13 additions and 1 deletions
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14
sys/sys/bus_dma.h
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@ -282,13 +282,25 @@ int bus_dmamem_alloc(bus_dma_tag_t dmat, void** vaddr, int flags,
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)
/*