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authorTom Rini <trini@ti.com>2013-02-26 16:35:33 -0500
committerTom Rini <trini@ti.com>2013-03-08 16:41:12 -0500
commit1c382ead7a0081140e4961f2a03a20abd5e41f05 (patch)
treed89e94e33fcdaf6780b7b675e38526eb263a5353 /arch/arm/cpu
parent98bc1228c800005e7addf95632e23079a236e5f5 (diff)
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am33xx: Update DDR3 EMIF configuration sequence
Based on http://processors.wiki.ti.com/index.php/AM335x_EMIF_Configuration_tips we need to re-work our sequence in config_sdram slightly to match what the TRM describes as the correct sequence. In our current (incorrect) sequence some edge cases may fail to initalize correctly. Signed-off-by: Tom Rini <trini@ti.com>
Diffstat (limited to 'arch/arm/cpu')
-rw-r--r--arch/arm/cpu/armv7/am33xx/ddr.c12
1 files changed, 9 insertions, 3 deletions
diff --git a/arch/arm/cpu/armv7/am33xx/ddr.c b/arch/arm/cpu/armv7/am33xx/ddr.c
index fd9fc4a..448cc40 100644
--- a/arch/arm/cpu/armv7/am33xx/ddr.c
+++ b/arch/arm/cpu/armv7/am33xx/ddr.c
@@ -45,13 +45,19 @@ static struct ddr_cmdtctrl *ioctrl_reg = {
*/
void config_sdram(const struct emif_regs *regs)
{
- writel(regs->ref_ctrl, &emif_reg->emif_sdram_ref_ctrl);
- writel(regs->ref_ctrl, &emif_reg->emif_sdram_ref_ctrl_shdw);
- if (regs->zq_config){
+ if (regs->zq_config) {
+ /*
+ * A value of 0x2800 for the REF CTRL will give us
+ * about 570us for a delay, which will be long enough
+ * to configure things.
+ */
+ writel(0x2800, &emif_reg->emif_sdram_ref_ctrl);
writel(regs->zq_config, &emif_reg->emif_zq_config);
writel(regs->sdram_config, &cstat->secure_emif_sdram_config);
}
writel(regs->sdram_config, &emif_reg->emif_sdram_config);
+ writel(regs->ref_ctrl, &emif_reg->emif_sdram_ref_ctrl);
+ writel(regs->ref_ctrl, &emif_reg->emif_sdram_ref_ctrl_shdw);
}
/**