Don't check and warn about pmap mismatch on every call to busdma sync.

With some recent busdma refactoring, sometimes it happens that a sync
op gets called when bus_dmamap_load() never got called, which results
in a spurious warning about a map mismatch when no sync operations will
actually happen anyway.  Now the check is done only if a sync operation
is actually performed, and the result of the check is a panic, not just
a printf.

Reviewed by:	cognet (who prevented me from donning a point hat)

1 files changed, 11 insertions, 17 deletions

diff --git a/sys/arm/arm/busdma_machdep-v6.c b/sys/arm/arm/busdma_machdep-v6.c
index ab69683..5324f80 100644
--- a/sys/arm/arm/busdma_machdep-v6.c
+++ b/sys/arm/arm/busdma_machdep-v6.c
@@ -1150,19 +1150,16 @@ _bus_dmamap_sync(bus_dma_tag_t dmat, bus_dmamap_t map, bus_dmasync_op_t op)
 	vm_offset_t bbuf;
 	char _tmp_cl[arm_dcache_align], _tmp_clend[arm_dcache_align];
 #endif
-		/* if buffer was from user space, it it possible that this
-		 * is not the same vm map. The fix is to map each page in
-		 * the buffer into the current address space (KVM) and then
-		 * do the bounce copy or sync list cache operation.
-		 *
-		 * The sync list entries are already broken into
-		 * their respective physical pages.
-		 */
-	if (!pmap_dmap_iscurrent(map->pmap))
-		printf("_bus_dmamap_sync: wrong user map: %p %x\n", map->pmap, op);
-
+	/*
+	 * If the buffer was from user space, it is possible that this is not
+	 * the same vm map, especially on a POST operation.  It's not clear that
+	 * dma on userland buffers can work at all right now, certainly not if a
+	 * partial cacheline flush has to be handled.  To be safe, until we're
+	 * able to test direct userland dma, panic on a map mismatch.
+	 */
 	if ((bpage = STAILQ_FIRST(&map->bpages)) != NULL) {
-
+		if (!pmap_dmap_iscurrent(map->pmap))
+			panic("_bus_dmamap_sync: wrong user map for bounce sync.");
 		/* Handle data bouncing. */
 		CTR4(KTR_BUSDMA, "%s: tag %p tag flags 0x%x op 0x%x "
 		    "performing bounce", __func__, dmat, dmat->flags, op);
@@ -1188,9 +1185,6 @@ _bus_dmamap_sync(bus_dma_tag_t dmat, bus_dmamap_t map, bus_dmasync_op_t op)
 		}
 
 		if (op & BUS_DMASYNC_POSTREAD) {
-			if (!pmap_dmap_iscurrent(map->pmap))
-			    panic("_bus_dmamap_sync: wrong user map. apply fix");
-
 			cpu_dcache_inv_range((vm_offset_t)bpage->vaddr,
 					bpage->datacount);
 			l2cache_inv_range((vm_offset_t)bpage->vaddr,
@@ -1230,6 +1224,8 @@ _bus_dmamap_sync(bus_dma_tag_t dmat, bus_dmamap_t map, bus_dmasync_op_t op)
 		return;
 
 	if (map->sync_count != 0) {
+		if (!pmap_dmap_iscurrent(map->pmap))
+			panic("_bus_dmamap_sync: wrong user map for sync.");
 		/* ARM caches are not self-snooping for dma */
 
 		sl = &map->slist[0];
@@ -1303,8 +1299,6 @@ _bus_dmamap_sync(bus_dma_tag_t dmat, bus_dmamap_t map, bus_dmasync_op_t op)
 
 #ifdef FIX_DMAP_BUS_DMASYNC_POSTREAD
 		case BUS_DMASYNC_POSTREAD:
-			if (!pmap_dmap_iscurrent(map->pmap))
-			     panic("_bus_dmamap_sync: wrong user map. apply fix");
 			while (sl != end) {
 					/* write back the unaligned portions */
 				vm_paddr_t physaddr;