diff --git a/include/asm-blackfin/mach-bf548/mem_init.h b/include/asm-blackfin/mach-bf548/mem_init.h
index befc2903d5a5..ab0b863eee66 100644
--- a/include/asm-blackfin/mach-bf548/mem_init.h
+++ b/include/asm-blackfin/mach-bf548/mem_init.h
@@ -29,16 +29,19 @@
  * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  */
 #define MIN_DDR_SCLK(x)	(x*(CONFIG_SCLK_HZ/1000/1000)/1000 + 1)
+#define MAX_DDR_SCLK(x)	(x*(CONFIG_SCLK_HZ/1000/1000)/1000)
+#define DDR_CLK_HZ(x)	(1000*1000*1000/x)
 
 #if (CONFIG_MEM_MT46V32M16_6T)
 #define DDR_SIZE	DEVSZ_512
 #define DDR_WIDTH	DEVWD_16
+#define DDR_MAX_tCK	13
 
 #define DDR_tRC		DDR_TRC(MIN_DDR_SCLK(60))
 #define DDR_tRAS	DDR_TRAS(MIN_DDR_SCLK(42))
 #define DDR_tRP		DDR_TRP(MIN_DDR_SCLK(15))
 #define DDR_tRFC	DDR_TRFC(MIN_DDR_SCLK(72))
-#define DDR_tREFI	DDR_TREFI(MIN_DDR_SCLK(7800))
+#define DDR_tREFI	DDR_TREFI(MAX_DDR_SCLK(7800))
 
 #define DDR_tRCD	DDR_TRCD(MIN_DDR_SCLK(15))
 #define DDR_tWTR	DDR_TWTR(1)
@@ -49,12 +52,13 @@
 #if (CONFIG_MEM_MT46V32M16_5B)
 #define DDR_SIZE	DEVSZ_512
 #define DDR_WIDTH	DEVWD_16
+#define DDR_MAX_tCK	13
 
 #define DDR_tRC		DDR_TRC(MIN_DDR_SCLK(55))
 #define DDR_tRAS	DDR_TRAS(MIN_DDR_SCLK(40))
 #define DDR_tRP		DDR_TRP(MIN_DDR_SCLK(15))
 #define DDR_tRFC	DDR_TRFC(MIN_DDR_SCLK(70))
-#define DDR_tREFI	DDR_TREFI(MIN_DDR_SCLK(7800))
+#define DDR_tREFI	DDR_TREFI(MAX_DDR_SCLK(7800))
 
 #define DDR_tRCD	DDR_TRCD(MIN_DDR_SCLK(15))
 #define DDR_tWTR	DDR_TWTR(2)
@@ -65,6 +69,7 @@
 #if (CONFIG_MEM_GENERIC_BOARD)
 #define DDR_SIZE	DEVSZ_512
 #define DDR_WIDTH	DEVWD_16
+#define DDR_MAX_tCK	13
 
 #define DDR_tRCD	DDR_TRCD(3)
 #define DDR_tWTR	DDR_TWTR(2)
@@ -77,14 +82,15 @@
 #define DDR_tREFI	DDR_TREFI(1288)
 #endif
 
-#if (CONFIG_SCLK_HZ <= 133333333)
-#define	DDR_CL		CL_2
-#elif (CONFIG_SCLK_HZ <= 166666666)
-#define	DDR_CL		CL_2_5
+#if (CONFIG_SCLK_HZ < DDR_CLK_HZ(DDR_MAX_tCK))
+# error "CONFIG_SCLK_HZ is too small (<DDR_CLK_HZ(DDR_MAX_tCK) Hz)."
+#elif(CONFIG_SCLK_HZ <= 133333333)
+# define	DDR_CL		CL_2
 #else
-#define	DDR_CL		CL_3
+# error "CONFIG_SCLK_HZ is too large (>133333333 Hz)."
 #endif
 
+
 #define mem_DDRCTL0	(DDR_tRP | DDR_tRAS | DDR_tRC | DDR_tRFC | DDR_tREFI)
 #define mem_DDRCTL1	(DDR_DATWIDTH | EXTBANK_1 | DDR_SIZE | DDR_WIDTH | DDR_tWTR \
 			| DDR_tMRD | DDR_tWR | DDR_tRCD)