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| author | zbb <zbb@FreeBSD.org> | 2015-07-08 13:52:59 +0000 |
|---|---|---|
| committer | zbb <zbb@FreeBSD.org> | 2015-07-08 13:52:59 +0000 |
| commit | ad70ced005b6c89457096f744618bb95ba71f003 (patch) | |
| tree | 76cdd2360c3f68817bb3850563b05804387c2a80 /sys/sys/bus_dma.h | |
| parent | 79ef161338c558af0dbe0928d4315be38a814695 (diff) | |
| download | FreeBSD-src-ad70ced005b6c89457096f744618bb95ba71f003.zip FreeBSD-src-ad70ced005b6c89457096f744618bb95ba71f003.tar.gz | |
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
Diffstat (limited to 'sys/sys/bus_dma.h')
| -rw-r--r-- | sys/sys/bus_dma.h | 14 |
1 files changed, 13 insertions, 1 deletions
diff --git a/sys/sys/bus_dma.h b/sys/sys/bus_dma.h index 4ea5b08..2a9d2ed 100644 --- a/sys/sys/bus_dma.h +++ b/sys/sys/bus_dma.h @@ -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) /* |
