Bug found

[Thomas Dörfler]

Leon,

the big question is, what is the definition of "clocks per usec". In
your view, this is the bus clock, in the view implemented, it is the
Timebase/DEC tick rate directly.

Maybe this helps...

wkr,
Thomas.



Leon Pollak wrote:
> Hello.
> 
> In 4.8.0 version the file ../c/src/lib/libcpu/powerpc/mpc8260/clock/clock.c 
> function clockOn (lines 94-95) has the following text:
> 
>  decrementer_value = rtems_configuration_get_microseconds_per_tick() *
>          rtems_cpu_configuration_get_clicks_per_usec() - 1;
> 
> while should be:
> 
>  decrementer_value = rtems_configuration_get_microseconds_per_tick() *
>          (rtems_cpu_configuration_get_clicks_per_usec() / 4 ) - 1;
> 
> (division by 4 is missing).
> 
> See G2 Core Reference Manual. It is said (Section 1.1.8.2):
> 
> "The decrementer is a 32-bit register that generates a decrementer interrupt 
> exception after a programmable delay. The contents of the decrementer register 
> are decremented once every four bus clock cycles, and the decrementer 
> exception is generated as the count passes through zero."
> 
> Thanks.


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