Re: [Xenomai-help] timer-handling adeos/xenomai on arm

[Sebastian Smolorz <Sebastian.Smolorz@domain.hid>]

Gilles Chanteperdrix wrote:
> Sebastian Smolorz wrote:
>  > Sebastian Smolorz wrote:
>  > > Gilles Chanteperdrix wrote:
>  > > > Schlägl "Manfred jun." wrote:
>  > > >  > Hi again!
>  > > >  >
>  > > >  > I've the presumption, there is something wrong with my
>  > > >  > timer-handling. Could you please take a look at my handling.
>  > > >  >
>  > > >  > Thanks in advance!
>  > > >
>  > > > The problem I see with your code is that you are updating
>  > > > ns_timer_lxlost in __ipipe_mach_acktimer, the integrator
>  > > > architecture code, which also uses a decrementer does not do that.
>  > > > Apart from that, I see nothing wrong.
>  > >
>  > > I see another one which has to do with the fact that __ipipe_mach_tsc
>  > > is updated both in __ipipe_mach_get_tsc and __ipipe_mach_set_dec. This
>  > > leads to double-added ticks because the latter funcion is called only
>  > > once a period and the former even more than once. So Xenomai counts
>  > > jiffies in /proc/xenomai/timer to fast. Manfred, can you confirm this?
>  >
>  > Forget this, my eyes weren't open this morning ... In 
>  > __ipipe_mach_get_tsc there is no update of __ipipe_mach_tsc, of course.
>
> Right, but __ipipe_mach_tsc and ns_timer_lxlost get also updated in
> __ipipe_mach_acktimer, this looks wrong, in the integrator
> implementation, they are updated in the timer interrupt, only if the
> timer is not stolen.

OK, let's speculate a little bit. (Maybe all of the following turns out to be 
completely wrong, but it wouldn't be the first time for me today. ;-) 
Hopefully Manfred can give some comments which pieces of my speculation are 
right.)

The timer counts down to zero, causes an interrupt and then reloads 
automatically with ns_timer_reload. So, when __ipipe_mach_acktimer is called 
ns_timer_reload ticks have passed and can be added to __ipipe_mach_tsc and 
ns_timer_lxlost. Some ticks later, __ipipe_mach_set_dec is executed, the 
passed ticks are added to __ipipe_mach_tsc and ns_timer_lxlost and the timer 
is reprogrammed to the new value.

Could be right ...

Sebastian