Mega busdma API commit.

Add two new arguments to bus_dma_tag_create(): lockfunc and lockfuncarg.
Lockfunc allows a driver to provide a function for managing its locking
semantics while using busdma.  At the moment, this is used for the
asynchronous busdma_swi and callback mechanism.  Two lockfunc implementations
are provided: busdma_lock_mutex() performs standard mutex operations on the
mutex that is specified from lockfuncarg.  dftl_lock() is a panic
implementation and is defaulted to when NULL, NULL are passed to
bus_dma_tag_create().  The only time that NULL, NULL should ever be used is
when the driver ensures that bus_dmamap_load() will not be deferred.
Drivers that do not provide their own locking can pass
busdma_lock_mutex,&Giant args in order to preserve the former behaviour.

sparc64 and powerpc do not provide real busdma_swi functions, so this is
largely a noop on those platforms.  The busdma_swi on is64 is not properly
locked yet, so warnings will be emitted on this platform when busdma
callback deferrals happen.

If anyone gets panics or warnings from dflt_lock() being called, please
let me know right away.

Reviewed by:	tmm, gibbs

1 files changed, 2 insertions, 1 deletions

diff --git a/sys/dev/sound/pci/t4dwave.c b/sys/dev/sound/pci/t4dwave.c
index cd7de77..19a92dc 100644
--- a/sys/dev/sound/pci/t4dwave.c
+++ b/sys/dev/sound/pci/t4dwave.c
@@ -854,7 +854,8 @@ tr_pci_attach(device_t dev)
 		/*highaddr*/BUS_SPACE_MAXADDR,
 		/*filter*/NULL, /*filterarg*/NULL,
 		/*maxsize*/tr->bufsz, /*nsegments*/1, /*maxsegz*/0x3ffff,
-		/*flags*/0, &tr->parent_dmat) != 0) {
+		/*flags*/0, /*lockfunc*/busdma_lock_mutex,
+		/*lockarg*/&Giant, &tr->parent_dmat) != 0) {
 		device_printf(dev, "unable to create dma tag\n");
 		goto bad;
 	}