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 <mel...@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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