On 12/8/08 3:10 PM, Josh Boyer wrote:
> On Mon, 08 Dec 2008 14:08:01 -0800
> Grant Erickson <[EMAIL PROTECTED]> wrote:
>
> Well, at the moment CONFIG_PPC4xx_IBM_DDR2 doesn't exist, and has no
> meaning. Adding a Kconfig option for it just so you can select an ECC
> option seems superfluous. Because if you select no for ECC, then you
> have a Kconfig option that does nothing. You could simply have:
>
> CONFIG_4xx_IBM_DDR2_ECC
>
> or something like that.
Reasonable enough.
> I'll buy that. Just start with ppc4xx_ecc.c with your initial support
> and then we can refactor as other implementations get added (if they
> do).
Sounds good.
>> SDRAM0: memory-controller {
>> compatible = "ibm,sdram-405ex", "ibm,sdram-4xx-ddr2";
>> dcr-reg = <0x010 0x002>;
>> ...
>> interrupt-parent = <&SDRAM0>;
>> interrupts = <0x0 0x1>;
>> interrupt-map = </* ECCDED Error */ 0x0 &UIC2 0x5 0x4
>> /* ECCSEC Error */ 0x1 &UIC2 0x6 0x4>;
>> ...
>> };
>
> More like this one.
>
>> or some such. My DTS expertise is near zero and growing.
>
> That's pretty darn good so far.
Great, thanks.
> Just to make sure, are you planning on just implementing a driver to
> deal with whatever settings the bootloader configured? E.g., if ECC is
> enabled deal with correctable/uncorrectable errors and if not, do
> nothing? Basically you are looking to implement a scrub driver, yes?
>
> I ask because since ECC is memory module specific and memory controller
> setup is pretty tricky, I think it's best to leave whatever
> configuration the bootloader set and work with that. Having to redo
> memory controller setups in Linux to enable ECC isn't something I'd
> look forward to.
Precisely. The driver will basically check if ECC is enabled (as was set/not
set by u-boot) and, if so, will take ECC SEC/DED interrupts, log SEC errors
to some data structure fetchable by a proc entry or some device node. For
DED errors, execute on some policy, at its simplest, generating a panic.
At no point will the driver/code attempt to change the controller
configuration beyond reading/clearing ECC event/interrupt status.
Regards,
Grant
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