Re: [Adeos-main] Re: Re: Porting to Intel IXP425

[Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>]

Schlägl Manfred jun. wrote:
> Am Montag, den 02.04.2007, 13:34 +0200 schrieb Richard Cochran:
> 
>>>Then you have to implement it like I described. 
>>>
>>>Take a look at the implementation for integrator-platforms.
>>>(Timer with wraparound)
>>
>>Well, as I said, the IXP425 one-shot timer mode does _not_ wrap around.
>>It just stops.
> 
> 
>>I'm not sure how (or why) to account for the clock ticks that transpire
>>during the interrupt handler.
>>
>>There are no clock ticks lost in __ipipe_mach_get_tsc, since this gets the
>>value of a free-flowing timer.
>>
>>Previously you wrote,
>>
>>
>>>These lost-ticks should be added to the global time-stamp (returned by
>>>get_tsc) and should mentioned at the linux-gettimeoffset-function also.
>>
>>Can you be more specific? What is the "linux-gettimeoffset-function" of
>>which you speak?
> 
> 
> Linux gettimeoffset calls a march-specific function
> (ixp4xx_gettimeoffset) which delivers the time in us since the last
> timer-tick (timer-interrupt).
> 
> 
>>>Lost-ticks could sum up to a bothering time-error.
>>
>>But in the plain-old Linux code, no such adjustment is made (using a
>>periodic timer, see below).
> 
> 
> In this implementation a time-stamp register is used. Excuse me, I
> misunderstood your mail before...
> Forget what i said. It's quite simpler to use such a timer for adeos. 
> Gilles Chanteperdrix is right.

Actually, I was looking at the IXP465 datasheet which has a free-running
counter with match register. But if I understand correctly, the IXP425
has the same free running counter as IXP465 but no match register.

-- 
                                                 Gilles Chanteperdrix