[U-Boot-Users] Software watchdog on mpc8247

[Jerry Van Baren]

Mike Rapoport wrote:
> On 8/25/05, Jerry Van Baren <gerald.vanbaren at smiths-aerospace.com> wrote:
> 
>>
>>Pointing out the obvious... looking at the disassembly, it isn't
>>enabling the watchdog (SWE).  I'm guessing that you disassembled code
>>where you had the watchdog disabled?
> 
> 
> The instruction
> fff031a0:       60 84 ff c3     ori     r4,r4,65479 
> actually enables watchdog (65479 dec = ffc7 hex) and SWE is bit 29 of SYPCR.

Well... yes and no.  65479 == 0xFFC7 as you point out, however the 
instruction has 0xFFC3 in it.  That's pretty odd.  Compiler problem?

>>I see you have PBME and LBME enabled (I'm looking at an 8260 manual,
>>assuming the 8247 is the same - feel free to correct me :-).  Do you
>>have a 60x bus and a local bus?  Is it possible you are having an
>>inadvertant bus error?  This wouldn't explain why it only happens when
>>you enable the WDT, however.  Puzzling.
> 
> 
> The 8247 does not have local bus, only 60x, but setting/clearing LBME
> does not affect the operation. If I don't enable the watchdog the
> system works fine.
> 
> Another thing I've noticed, most or even all 8260 based systems have
> #undef CONFIG_WATCHDOG
> in their config 

Well, they are a real pain, generally more than they are worth.  My 
co-worker says we had it working on our 8260 board at one point, but 
Things Changed and it stopped working (it was a never-ending battle to 
sprinkle enough kick-the-dogs in the start up code) and so it ended up 
turned off.  He said it worked fine once we got through initialization 
and the was kernel running...

gvb