driver/ddr/fsl: Fix MRC_CYC calculation for DDR3
For DDR controller version 4.7 or newer, MRC_CYC (mode register set
cycle time) is max(tMRD, tMOD). tMRD is 4nCK, or 8nCK (RDIMM). tMOD
is max(12nCK, 15ns) according to JEDEC spec.
DDR4 is not affected by this change.
Signed-off-by: York Sun <yorksun@freescale.com>
diff --git a/drivers/ddr/fsl/ctrl_regs.c b/drivers/ddr/fsl/ctrl_regs.c
index fe8aa98..03d7ff1 100644
--- a/drivers/ddr/fsl/ctrl_regs.c
+++ b/drivers/ddr/fsl/ctrl_regs.c
@@ -324,6 +324,7 @@
#elif defined(CONFIG_SYS_FSL_DDR3)
unsigned int data_rate = get_ddr_freq(0);
int txp;
+ unsigned int ip_rev;
int odt_overlap;
/*
* (tXARD and tXARDS). Empirical?
@@ -336,7 +337,25 @@
*/
txp = max((int)mclk_ps * 3, (mclk_ps > 1540 ? 7500 : 6000));
- tmrd_mclk = 4;
+ ip_rev = fsl_ddr_get_version();
+ if (ip_rev >= 0x40700) {
+ /*
+ * MRS_CYC = max(tMRD, tMOD)
+ * tMRD = 4nCK (8nCK for RDIMM)
+ * tMOD = max(12nCK, 15ns)
+ */
+ tmrd_mclk = max((unsigned int)12, picos_to_mclk(15000));
+ } else {
+ /*
+ * MRS_CYC = tMRD
+ * tMRD = 4nCK (8nCK for RDIMM)
+ */
+ if (popts->registered_dimm_en)
+ tmrd_mclk = 8;
+ else
+ tmrd_mclk = 4;
+ }
+
/* set the turnaround time */
/*