The 8572 DDR erratum1:
DDR controller may enter an illegal state when operating
in 32-bit bus mode with 4-beat bursts.
Description:
When operating with a 32-bit bus, it is recommended that
DDR_SDRAM_CFG[8_BE] is cleared when DDR2 memories are used.
This forces the DDR controller to use 4-beat bursts when
communicating to the DRAMs. However, an issue exists that
could lead to data corruption when the DDR controller is
in 32-bit bus mode while using 4-beat bursts.
Projected Impact:
If the DDR controller is operating in 32-bit bus mode with
4-beat bursts, then the controller may enter into a bad state.
All subsequent reads from memory is corrupted.
Four-beat bursts with a 32-bit bus only is used with DDR2 memories.
Therefore, this erratum does not affect DDR3 mode.
Work Arounds:
To work around this issue, software must set DEBUG_1[31] in
DDR memory mapped space (CCSRBAR offset + 0x2f00 for DDR_1
and CCSRBAR offset + 0x6f00 for DDR_2).
Currenlty, the code is using incorrect register DDR_SDRAM_CFG_2
as condition, but it should be DDR_SDRAM_CFG register.
Signed-off-by: Dave Liu <[EMAIL PROTECTED]>
---
cpu/mpc85xx/ddr-gen3.c | 9 ++++++---
1 files changed, 6 insertions(+), 3 deletions(-)
diff --git a/cpu/mpc85xx/ddr-gen3.c b/cpu/mpc85xx/ddr-gen3.c
index e0654bb..a2b45c5 100644
--- a/cpu/mpc85xx/ddr-gen3.c
+++ b/cpu/mpc85xx/ddr-gen3.c
@@ -79,15 +79,18 @@ void fsl_ddr_set_memctl_regs(const fsl_ddr_cfg_regs_t *regs,
out_be32(&ddr->ddr_sdram_rcw_2, regs->ddr_sdram_rcw_2);
/*
- * 32-bit workaround for DDR2
- * 32_BE
+ * For 8572 DDR1 erratum - DDR controller may enter illegal state
+ * when operatiing in 32-bit bus mode with 4-beat bursts,
+ * This erratum does not affect DDR3 mode, only for DDR2 mode.
*/
+#ifdef CONFIG_MPC8572
if ((((in_be32(&ddr->sdram_cfg) >> 24) & 0x7) == SDRAM_TYPE_DDR2)
- && in_be32(&ddr->sdram_cfg_2) & 0x80000) {
+ && in_be32(&ddr->sdram_cfg) & 0x80000) {
/* set DEBUG_1[31] */
u32 temp = in_be32(&ddr->debug_1);
out_be32(&ddr->debug_1, temp | 1);
}
+#endif
/*
* 200 painful micro-seconds must elapse between
--
1.5.4
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