[U-Boot] PPC440GX: DDR ECC init time.

[Felix Radensky <felix@embedded-sol.com>]

Hi,  Stefan

Stefan Roese wrote:
> On Monday 07 September 2009 15:57:19 Wouter Eckhardt wrote:
>   
>> Well, I've been trying to work this into my U-Boot. I haven't succeeded
>> so far. Basically, the cache stuff in 4xx_spd_ddr2.c consists of setting
>> up a TLB without the CACHE_INHIBITED bit and then using some cache
>> instructions to fill up memory. That's what I've been trying to do, but
>> my call to change_tlb() hangs because of the invalidate_dcache() call
>> (bad trap exceptions). What could be going on here?
>>
>> I'll try and set up the DDR TLB dynamically instead of statically (in
>> init.S) and see if I can get that working.
>>     
>
> Yes. That's what I would do as well.
>  
>   
>> By the way, I've also stumbled upon some other VERY strange behavior. If
>> I leave the ecc_init() in its original state and just add in a puts(" ")
>> call at the beginning of the function, ECC generation is finished VERY
>> quickly. What influence could adding the puts() call possibly have on
>> the speed of generating ECC values in DDR?
>>     
>
> That's strange indeed. I suspect a problem in the code then. Try looking at 
> the generated assembler code and/or debug with an BDI2000/3000.
>   
Not exactly related to the subject under discussion, but I thought I'd 
mention it.

I had problems with ecc_init() on a custom 460EX board with soldered DDR2.
Right after ecc_init() u-boot was crashing on PLB access. I've modified 
the code
to use program_ecc_addr() instead of ecc_init(), and problem was solved. 
I was
wandering why use two different ECC initialization routines for SPD and 
soldered
cases, when program_ecc_addr() can do the job in both cases, while 
ecc_init()
apparently has issues ?

Thanks.

Felix.

> Cheers,
> Stefan
>
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