[U-Boot-Users] AMCC PPC440EPx/sequoia stability question...

[Dave Littell]

Stefan Roese wrote:
> On Wednesday 23 April 2008, Dave Littell wrote:
>> I'm working on an AMCC PPC440EPx-based platform that's similar to the
>> Sequoia.  The board runs pretty well, but occasionally takes exceptions
>> both in U-Boot and while running Linux.  The exceptions vary from
>> Illegal Instructions to FP Unavailable to FP Unimplemented to ITLB and
>> DTLB Errors, to DSI, etc., which made us believe there's a problem with
>> SDRAM.
> 
> Yes, this is my first idea too. Almost every time such "random" errors are 
> seen, SDRAM setup/initialization is the cause for it.
> 
>> Sometimes there are simple hard lockups from which even the JTAG 
>> can't regain control.  However, the SDRAM physical/electrical and DDR
>> Controller configurations have been investigated in detail (and some
>> corrections made) with no resulting improvement in the exception behavior.
> 
> Is the SDRAM termination similar to the one used on Sequoia too? Are you using 
> soldered chips and not DIMM modules? Is ECC available?
> 

Termination: very likely - they stayed very close to Sequoia, but I'll ask.

We're using soldered chips and there's no ECC.

>> We see problems primarily at 667 MHz but have noted some issues at 533
>> MHz as well.  Some boards seem particularly susceptible to this while
>> others rarely (if ever) exhibit the problem.
>>
>> At this point all possibilities are on the table and I'm looking for any
>> input from anyone with experience (good, bad, or whatever) with this
>> processor and/or designs similar to the Sequoia.
> 
> If you scan the U-Boot mailing list for 440EPx/Denali DDR2 problems, you will 
> most likely find some references.
> 

Will do, thanks for the pointer.

> Please note that I recently introduced a CFG_MEM_TOP_HIDE option for the 
> 440EPx CHIP 11 errata. I suggest you take a look at this too and see if this 
> changes your behavior.
> 

I remember this - PPC440EPx Revision A errata CHIP_11, right?


Thanks,
Dave