diff --git a/arch/blackfin/Kconfig b/arch/blackfin/Kconfig
index 785d8b4..b87634e 100644
--- a/arch/blackfin/Kconfig
+++ b/arch/blackfin/Kconfig
@@ -685,6 +685,8 @@
 	prompt "Uncached SDRAM region"
 	default DMA_UNCACHED_1M
 	depends on BFIN_DMA_5XX
+config DMA_UNCACHED_4M
+	bool "Enable 4M DMA region"
 config DMA_UNCACHED_2M
 	bool "Enable 2M DMA region"
 config DMA_UNCACHED_1M
diff --git a/include/asm-blackfin/bfin-global.h b/include/asm-blackfin/bfin-global.h
index 716df7c..a9248d8 100644
--- a/include/asm-blackfin/bfin-global.h
+++ b/include/asm-blackfin/bfin-global.h
@@ -37,7 +37,9 @@
 #include <linux/linkage.h>
 #include <linux/types.h>
 
-#if defined(CONFIG_DMA_UNCACHED_2M)
+#if defined(CONFIG_DMA_UNCACHED_4M)
+# define DMA_UNCACHED_REGION (4 * 1024 * 1024)
+#elif defined(CONFIG_DMA_UNCACHED_2M)
 # define DMA_UNCACHED_REGION (2 * 1024 * 1024)
 #elif defined(CONFIG_DMA_UNCACHED_1M)
 # define DMA_UNCACHED_REGION (1024 * 1024)