mpc83xx: Improve the performance of DDR memory

modify the CAS timings. my understanding is that these
settings decrease various wait times in the DDR interface.
Because these wait times are in clock cycles, and the DDR
clock on the 8315 RDB runs slower than on some other 83xx
platforms, we can dial down these values without a problem,
thereby decreasing the latency of memory a little.

Signed-off-by: Howard Gregory <Greg.Howard@freescale.com>
Signed-off-by: Dave Liu <daveliu@freescale.com>
Signed-off-by: Kim Phillips <kim.phillips@freescale.com>

diff --git a/include/configs/MPC8315ERDB.h b/include/configs/MPC8315ERDB.h
index 1225270ffbeb938ef478f95b1c793d720869fa32..add65f03d059166fd5ae77cd18d8e7b0645dca78 100644 (file)
--- a/include/configs/MPC8315ERDB.h
+++ b/include/configs/MPC8315ERDB.h
@@ -118,23 +118,23 @@
                                | ( 8 << TIMING_CFG0_ODT_PD_EXIT_SHIFT ) \
                                | ( 2 << TIMING_CFG0_MRS_CYC_SHIFT ) )
                                /* 0x00220802 */
-#define CONFIG_SYS_DDR_TIMING_1        ( ( 3 << TIMING_CFG1_PRETOACT_SHIFT ) \
-                               | ( 9 << TIMING_CFG1_ACTTOPRE_SHIFT ) \
-                               | ( 3 << TIMING_CFG1_ACTTORW_SHIFT ) \
+#define CONFIG_SYS_DDR_TIMING_1        ( ( 2 << TIMING_CFG1_PRETOACT_SHIFT ) \
+                               | ( 7 << TIMING_CFG1_ACTTOPRE_SHIFT ) \
+                               | ( 2 << TIMING_CFG1_ACTTORW_SHIFT ) \
                                | ( 5 << TIMING_CFG1_CASLAT_SHIFT ) \
                                | ( 6 << TIMING_CFG1_REFREC_SHIFT ) \
                                | ( 2 << TIMING_CFG1_WRREC_SHIFT ) \
                                | ( 2 << TIMING_CFG1_ACTTOACT_SHIFT ) \
                                | ( 2 << TIMING_CFG1_WRTORD_SHIFT ) )
-                               /* 0x39356222 */
+                               /* 0x27256222 */
 #define CONFIG_SYS_DDR_TIMING_2        ( ( 1 << TIMING_CFG2_ADD_LAT_SHIFT ) \
                                | ( 4 << TIMING_CFG2_CPO_SHIFT ) \
                                | ( 2 << TIMING_CFG2_WR_LAT_DELAY_SHIFT ) \
                                | ( 2 << TIMING_CFG2_RD_TO_PRE_SHIFT ) \
                                | ( 2 << TIMING_CFG2_WR_DATA_DELAY_SHIFT ) \
                                | ( 3 << TIMING_CFG2_CKE_PLS_SHIFT ) \
-                               | ( 7 << TIMING_CFG2_FOUR_ACT_SHIFT) )
-                               /* 0x121048c7 */
+                               | ( 5 << TIMING_CFG2_FOUR_ACT_SHIFT) )
+                               /* 0x121048c5 */
 #define CONFIG_SYS_DDR_INTERVAL        ( ( 0x0360 << SDRAM_INTERVAL_REFINT_SHIFT ) \
                                | ( 0x0100 << SDRAM_INTERVAL_BSTOPRE_SHIFT ) )
                                /* 0x03600100 */