Clock not running (was Re: RTEMS4.7 and its tool chain (Re: powerpc mvme5500 clock off by factor of 150))

Till Straumann strauman at
Tue Mar 8 21:35:48 UTC 2005

Peter Dufault wrote:

> On Mar 8, 2005, at 3:39 PM, Till Straumann wrote:
>> Hence, you'd have to print the GPP_Interrupt_Cause register contents
>> to find the culprit [why the code in irq.c is so complicated is a 
>> mystery to me].
> The higher level code had derived register "56" as I'd mentioned, 
> which traced back to the serial port interrupt.  Printing out the 
> ever-pending GPP_Interrupt_Cause is "0x01", which also points to the 
> serial port.

> I wish there was a way to see that a PPC decrementer interrupt was 
> pending, because then I'd just call the decrementer ISR when interrupt 
> "56" was called and an interrupt was pending as a proof that this is 
> the problem, but I don't see that that is visible in any register.
> On the web I see references to errata on the serial port on the 
> undocumented interface chip. 

Not necessarily a HW bug. Could be that MotLoad uses the serial 
interface in interrupt driven
mode, the BSP never touches it and printk() raises interrupts. Again: 
this should go away
if pending irqs are cleared after masking in the initialization routine.


> Peter
> Peter Dufault
> HD Associates, Inc.

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