am335x: ddr_defs: Update EMIF parameters

EMIF parameters are calculated based on the AC timing
parameters from the SDRAM datasheet and the DDR frequency.

Current values for these paramters in AM335x U-Boot code,
though reliable, are not fully optimal. The most optimal
settings can be derived based on the guidelines published
at [1]. A pre-computed set of values with the most optimum
settings for AM335x EVM and BeagleBone can be found at [2].

[1] http://processors.wiki.ti.com/index.php/AM335x_EMIF_Configuration_tips
[2] http://processors.wiki.ti.com/index.php/OMAP_and_Sitara_CCS_support#AM335x

Signed-off-by: Vaibhav Bedia <vaibhav.bedia@ti.com>
Signed-off-by: Tom Rini <trini@ti.com>

arch/arm/include/asm/arch-am33xx/ddr_defs.h

@@ -29,11 +29,11 @@
 #define CMD_DELAY		0x00
 #define PHY_DLL_LOCK_DIFF	0x0
 
-#define DDR2_EMIF_READ_LATENCY	0x05
-#define DDR2_EMIF_TIM1		0x0666B3D6
-#define DDR2_EMIF_TIM2		0x143731DA
-#define DDR2_EMIF_TIM3		0x00000347
-#define DDR2_EMIF_SDCFG		0x43805332
+#define DDR2_EMIF_READ_LATENCY	0x100005	/* Enable Dynamic Power Down */
+#define DDR2_EMIF_TIM1		0x0666B3C9
+#define DDR2_EMIF_TIM2		0x243631CA
+#define DDR2_EMIF_TIM3		0x0000033F
+#define DDR2_EMIF_SDCFG		0x41805332
 #define DDR2_EMIF_SDREF		0x0000081a
 #define DDR2_DLL_LOCK_DIFF	0x0
 #define DDR2_RATIO		0x80