PPC440 DDR setup: Set SDRAM0_CFG0[PMU]=0 for best performance
AMCC suggested to set the PMU bit to 0 for best performace on
the PPC440 DDR controller.
Please see doc/README.440-DDR-performance for details.
Patch by Stefan Roese, 28 Jul 2006
diff --git a/cpu/ppc4xx/sdram.c b/cpu/ppc4xx/sdram.c
index e31d59d..faeea5c 100644
--- a/cpu/ppc4xx/sdram.c
+++ b/cpu/ppc4xx/sdram.c
@@ -379,7 +379,7 @@
/*
* Enable the controller, then wait for DCEN to complete
*/
- mtsdram(mem_cfg0, 0x86000000); /* DCEN=1, PMUD=1, 64-bit */
+ mtsdram(mem_cfg0, 0x82000000); /* DCEN=1, PMUD=0, 64-bit */
udelay(10000);
if (get_ram_size(0, mb0cf[i].size) == mb0cf[i].size) {
diff --git a/cpu/ppc4xx/spd_sdram.c b/cpu/ppc4xx/spd_sdram.c
index c0a6933..c24456b 100644
--- a/cpu/ppc4xx/spd_sdram.c
+++ b/cpu/ppc4xx/spd_sdram.c
@@ -1007,9 +1007,9 @@
}
/*
- * program Page Management Unit
+ * program Page Management Unit (0 == enabled)
*/
- cfg0 |= SDRAM_CFG0_PMUD;
+ cfg0 &= ~SDRAM_CFG0_PMUD;
/*
* program Memory Controller Options 0