[U-Boot] [PATCH 1/5] 8xxx: Add 'ecc' command

[Peter Tyser]

Hi Wolfgang,

> In message <1256258353-25589-1-git-send-email-ptyser at xes-inc.com> you wrote:
>> Add a new 'ecc' command to interact with the 85xx and 86xx DDR ECC
>> registers.  The 'ecc' command can inject data/ECC errors to simulate
>> errors and provides an 'info' subcommand which displays ECC error
>> information such as failure address, read vs expected data/ECC,
>> physical signal which failed, single-bit error count, and multiple bit
>> error occurrence.  An example of the 'ecc info' command follows:
> 
> We already have similar commands for other architectures, see for
> example cpu/mpc83xx/ecc.c
> 
> I'm not sure if it's possible to use a common implementation, but I
> would like to ask you to check if this is possible.

83xx, 85xx, and 86xx could all share an implementation I believe. I 
didn't integrate the 83xx in this patch because it seemed to have a 
different "goal" than the patch I submitted.  The 83xx implementation 
supported a high degree of tweaking registers which I personally find 
unnecessary for general use.  I think that if someone wants that level 
of control, they could just modify the registers directly since they 
have to have the 83xx user's manual handy anyway.

The implementation I submitted has limited, common features and much 
better error reporting.  The error reporting is the feature that would 
be used 98% of the time, not the tweaking of registers.  I'd be happy to 
include the 83xx implementation in this patch, but I'd vote to strip out 
most of the current 83xx features - ie basically remove the 83xx ecc 
code and replace it with the  85/86xx implementation I submitted.  Would 
83xx people be OK with this?  Or have any suggestions on what the 
combined implementation should look like?

> In any case I ask that we use a common user interface for both
> implementations. It makes no sense that the same command name behaves
> differently on different boards (even from the same vendor).

I see your point.  As far as a common implementation, what did you have 
in mind?  Are you referring to only consolidating the 83xx/85xx/86xx 
implementations?  I'm fine with that, but don't think you could expand 
the "common interface" much past them as ECC reporting/injection 
features vary greatly from architecture to architecture.

Best,
Peter