Date: Sat, 15 Nov 2014 03:39:58 +0000 (UTC) From: Ian Lepore <ian@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r274538 - head/sys/arm/arm Message-ID: <201411150339.sAF3dwbg039719@svn.freebsd.org>
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Author: ian Date: Sat Nov 15 03:39:58 2014 New Revision: 274538 URL: https://svnweb.freebsd.org/changeset/base/274538 Log: When doing busdma sync ops for BUSDMA_COHERENT memory, there is no need for cache maintenance operations, but ensure that all prior writes have reached memory when doing a PREWRITE sync. Submitted by: Michal Meloun <meloun@miracle.cz> Modified: head/sys/arm/arm/busdma_machdep-v6.c Modified: head/sys/arm/arm/busdma_machdep-v6.c ============================================================================== --- head/sys/arm/arm/busdma_machdep-v6.c Sat Nov 15 03:34:34 2014 (r274537) +++ head/sys/arm/arm/busdma_machdep-v6.c Sat Nov 15 03:39:58 2014 (r274538) @@ -1385,8 +1385,18 @@ _bus_dmamap_sync(bus_dma_tag_t dmat, bus dmat->bounce_zone->total_bounced++; } } - if (map->flags & DMAMAP_COHERENT) + + /* + * For COHERENT memory no cache maintenance is necessary, but ensure all + * writes have reached memory for the PREWRITE case. + */ + if (map->flags & DMAMAP_COHERENT) { + if (op & BUS_DMASYNC_PREWRITE) { + dsb(); + cpu_l2cache_drain_writebuf(); + } return; + } if (map->sync_count != 0) { if (!pmap_dmap_iscurrent(map->pmap))
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