[U-Boot-Users] Question on ECC SDRAM initialization in PPC4xx

[U-Boot-Users] Question on ECC SDRAM initialization in PPC4xx

[Jeff Mann]

In the ppc4xx cpu source files, I see that ECC for SDRAM is supported.
The code checks some settings
	((read_spd(11)==2) && (read_spd(6)==40) && (read_spd(14)==8)
and then enables ECC on the processor. 

*Does this automatically detect the presence of a SDRAM chips connected
in an ECC configuration?* Are additional software configuration settings
needed before this point to enable ECC?

SOURCE ./cpu/ppc4xx/spd_sdram.c

/* now check for ECC ability of module. We only support ECC
 *   on 32 bit wide devices with 8 bit ECC.
 */
if ((read_spd(11)==2) && (read_spd(6)==40) && (read_spd(14)==8)) {
	sdram0_ecccfg = 0xf << SDRAM0_ECCCFG_SHIFT;
	ecc_on = 1;
} else {
	sdram0_ecccfg = 0;
	ecc_on = 0;
}

Thanks,
Jeff

[U-Boot-Users] Question on ECC SDRAM initialization in PPC4xx

[Stefan Roese]

Hi Jeff,

On Friday 04 August 2006 19:01, Jeff Mann wrote:
> In the ppc4xx cpu source files, I see that ECC for SDRAM is supported.
> The code checks some settings
> 	((read_spd(11)==2) && (read_spd(6)==40) && (read_spd(14)==8)
> and then enables ECC on the processor.
>
> *Does this automatically detect the presence of a SDRAM chips connected
> in an ECC configuration?* Are additional software configuration settings
> needed before this point to enable ECC?

Please note that the spd_sdram code handles 405 SDRAM and 440 DDR. Your code 
references the 405 SDRAM init code. IIRC, the 440 part of the code doesn't 
seem to support ECC right now.

What are you looking for exactly? For a know to be working ECC init (at least 
for me), please take a look at the non SPD 4xx SDRAM init code 
cpu/ppc4xx/sdram.c. Here you will find code to setup and init the 440 DDR 
controller with and without ECC support (CONFIG_SDRAM_ECC).

Best regards,
Stefan

[U-Boot-Users] Question on ECC SDRAM initialization in PPC4xx

[Jeff Mann]

>What are you looking for exactly? For a know to be working ECC init (at
least for me), please take a look at the non SPD 4xx SDRAM init code
cpu/ppc4xx/sdram.c. Here you will find code to setup and init the 440
DDR controller with and without ECC support (CONFIG_SDRAM_ECC).

Ok, I see it now:
  #ifdef CONFIG_SDRAM_ECC
  static void ecc_init(ulong start, ulong size)
  {
  ...
  }
and see the definition it requires defined. Thanks for the help.

-J.Mann