To Chip density 4Gb, tRFC should be 300ns, see
"Table 61 — Refresh parameters by device density" of JESD79-3E.
tXS(min) is max(5nCK, tRFC(min) + 10ns).
Signed-off-by: Peng Fan <Peng.Fan@freescale.com>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Tim Harvey <tharvey@gateworks.com>
Reviewed-by: Stefano Babic <sbabic@denx.de>
                txs = DIV_ROUND_UP(170000, clkper) - 1;
                break;
        case 4: /* 4Gb per chip */
-               trfc = DIV_ROUND_UP(260000, clkper) - 1;
-               txs = DIV_ROUND_UP(270000, clkper) - 1;
+               trfc = DIV_ROUND_UP(300000, clkper) - 1;
+               txs = DIV_ROUND_UP(310000, clkper) - 1;
                break;
        case 8: /* 8Gb per chip */
                trfc = DIV_ROUND_UP(350000, clkper) - 1;