diff --git a/[refs] b/[refs]
index 34695556f8ae..db1faa37816f 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: b476e2951fcf7a25574b7b193944b041687f3ed4
+refs/heads/master: 9ca24e2e19325edc3ed0b437657d26219b7a768a
diff --git a/trunk/mm/Kconfig b/trunk/mm/Kconfig
index 3bea74f1ccfe..e742d06285b7 100644
--- a/trunk/mm/Kconfig
+++ b/trunk/mm/Kconfig
@@ -263,8 +263,14 @@ config ZONE_DMA_FLAG
 	default "1"
 
 config BOUNCE
-	def_bool y
+	bool "Enable bounce buffers"
+	default y
 	depends on BLOCK && MMU && (ZONE_DMA || HIGHMEM)
+	help
+	  Enable bounce buffers for devices that cannot access
+	  the full range of memory available to the CPU. Enabled
+	  by default when ZONE_DMA or HIGHMEM is selected, but you
+	  may say n to override this.
 
 # On the 'tile' arch, USB OHCI needs the bounce pool since tilegx will often
 # have more than 4GB of memory, but we don't currently use the IOTLB to present