[U-Boot] SDRAM error for RD_EN and 2T_EN

hendrik hendrik.vastech at gmail.com
Mon Feb 16 10:50:08 CET 2009


hi all

I am going through the SPD DRAM setup for my mpc8548 board (using DDR2) 
- when I run uboot I get an error saying:
   
    Error: DDR_SDRAM_CFG[RD_EN] and DDR_SDRAM_CFG[2T_EN]  should not be 
set at the same time. 

As far as I could tell, neither of these two settings are within my 
control:

RD_EN is set by "populate_memctl_options" according to "spd->dimm_type" 
(In my case it is a Mini-RDIMM )

2T_EN is set in ddr/options.c and is hard coded as  popts->twoT_en = 1;
In U-boot1.2 i found 2T timing is dependant on the CPU version, Should 
this still be the case? in spd)sdram.c:

            if (pvr != PVR_85xx_REV1) {
    #if defined(CONFIG_DDR_2T_TIMING)
                /*
                 * Enable 2T timing by setting sdram_cfg[16].
                 */
                sdram_cfg |= 0x8000;        /* 2T_EN */
    #endif
            }


What should i do to get rid of this error? My initial efforts show by 
hacking RD_en = 0 is the only way to get my board to boot.  but this 
roes not feel like the way to go. I would appreciate any help.
thanks Hendrik




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