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authorAnatolij Gustschin <agust@denx.de>2013-02-08 00:03:49 +0000
committerWolfgang Denk <wd@denx.de>2013-03-09 08:23:02 +0100
commita615dfda8c2041dd98ecd238d45f3bc35e495b44 (patch)
treeb177e8e05649ba7da7f8f7dcfe309fb29b7aef68 /arch/powerpc/cpu/mpc512x
parentfcc7fe425183f9ec95fba33d041eb359d0a3a598 (diff)
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mpc512x: Adjust the DRAM init sequence to the datasheet spec
Do maintain a 200 usecs period of stable power and clock before asserting the CKE signal and sending commands, have at least 200 DRAM clock cycles pass after initialization before data access. Signed-off-by: Anatolij Gustschin <agust@denx.de>
Diffstat (limited to 'arch/powerpc/cpu/mpc512x')
-rw-r--r--arch/powerpc/cpu/mpc512x/fixed_sdram.c17
1 files changed, 16 insertions, 1 deletions
diff --git a/arch/powerpc/cpu/mpc512x/fixed_sdram.c b/arch/powerpc/cpu/mpc512x/fixed_sdram.c
index 550cbd0..6635fb0 100644
--- a/arch/powerpc/cpu/mpc512x/fixed_sdram.c
+++ b/arch/powerpc/cpu/mpc512x/fixed_sdram.c
@@ -99,7 +99,19 @@ long int fixed_sdram(ddr512x_config_t *mddrc_config,
sync_law(&im->sysconf.ddrlaw.ar);
/* DDR Enable */
- out_be32(&im->mddrc.ddr_sys_config, MDDRC_SYS_CFG_EN);
+ /*
+ * the "enable" combination: DRAM controller out of reset,
+ * clock enabled, command mode -- BUT leave CKE low for now
+ */
+ i = MDDRC_SYS_CFG_EN & ~MDDRC_SYS_CFG_CKE_MASK;
+ out_be32(&im->mddrc.ddr_sys_config, i);
+ /* maintain 200 microseconds of stable power and clock */
+ udelay(200);
+ /* apply a NOP, it shouldn't harm */
+ out_be32(&im->mddrc.ddr_command, CONFIG_SYS_DDRCMD_NOP);
+ /* now assert CKE (high) */
+ i |= MDDRC_SYS_CFG_CKE_MASK;
+ out_be32(&im->mddrc.ddr_sys_config, i);
/* Initialize DDR Priority Manager */
out_be32(&im->mddrc.prioman_config1, CONFIG_SYS_MDDRCGRP_PM_CFG1);
@@ -148,6 +160,9 @@ long int fixed_sdram(ddr512x_config_t *mddrc_config,
out_be32(&im->mddrc.ddr_time_config0, mddrc_config->ddr_time_config0);
out_be32(&im->mddrc.ddr_sys_config, mddrc_config->ddr_sys_config);
+ /* Allow for the DLL to startup before accessing data */
+ udelay(10);
+
msize = get_ram_size(CONFIG_SYS_DDR_BASE, CONFIG_SYS_MAX_RAM_SIZE);
/* Fix DDR Local Window for new size */
out_be32(&im->sysconf.ddrlaw.ar, __ilog2(msize) - 1);