[U-Boot] [PATCH 5/7] OMAP5: EMIF: Add support for DDR3 device

[Tom Rini]

On 05/23/2012 05:22 AM, R, Sricharan wrote:
> Hi Tom,
>>>
>>>   ah, this is what is there on OMAP5.
>>>     3 for DDR3
>>>     4 for LPDDR2-S4,
>>>     5 for LPDDR2-S2
>>
>>
>> 4/5 are listed as reserved here :( http://www.ti.com/lit/pdf/spruh73
>>
>>
>>> Atleast DDR3 encoding is same. So we can differentiate bw DDR3 and 2
>>> in same way.
>>> Is the reset value set correctly on am335x according to the device
>>> connected?
>>
>>
>> I'll have to do some checking as the code doesn't check that today.
>>
>   The reset value reflects the connected device correctly for lpddr2 and ddr3.
>   Is that the same case in am33xx platforms  ?

Yes, it's 3 on DDR3 and 2 on (non-LP) DDR2.  I spent some time yesterday 
starting on splitting up emif-common (am33xx does not have DMM) and 
making am33xx link at least with the common code.  My idea is to add a 
few more defines and make that part of do_sdram_init be:
if (!in_sdram) {
   switch(reg_sdram_type) {
#ifdef CONFIG_EMIF4_DDR2
     case 2:
       ddr2_init();
       break;
#ifdef CONFIG_EMFI4_DDR3
     case 3:
       ddr3_init();
       break;
#endif
#ifdef CONFIG_EMIF4_LPDDR2
     case 4:
     case 5:
       lpddr2_init();
       break;
#endif
     default:
       panic("Unsupported DDR type connected to EMIF4");
   }
}

And move lpddr2_init to emif4-lpddr2.c, and so forth.  My experimenting 
yesterday lead me to conclude that EMIF_MOD_ID_REGISTER behaves as is 
documented for am33xx on omap4/5 so what we're doing should be feasible. 
  I'm going to try and locally make the ddr3 patches work on the am33xx 
DDR3 board as a way to prove that out and if it works, and we're fine 
with what I've laid out above, start working towards that layout.

-- 
Tom