JD wrote:
> I was wanting to a similar(ish) thing but writing out the I/O pins
> instead.
>
> My thought was to create a driver attached to the 2nd timer of the cpu
> and run the writing of the I/O in kernel land each time the timer
> interrupt occurs.
>
> Looking a little closer at kernel code and the meager marvell CPU docs
> I could find, it appears that both timer 1 & 2 share the same
> interrupt (timer 1 being used for the system clock)
>
> Anyone know otherwise?
>
> I could add a shared interrupt I guess, if I made changes to the timer
> to allow interrupt sharing, but I dont know if thats such a good idea :)
I think this is a BAD (TM) idea! Why don't you use kernel timers? You
schedule a task to run after as many jiffies as you want. And since you
know the HZ value you can convert this to msecs. But remember that since
linux (the vanilla version of the kernel) is not a realtime os you can
never be sure that a task you scheduled after x jiffies will run exactly
after x jiffies!
Fotis
>
>
> --- In "fulatoro" <> wrote:
>> Well, you might have a point, however, I am reading IO pins and I
>> would like to have better granularity than the 10ms System clock, I
>> realize that I can probably improve things by writing a device driver
>> and doing the work in the kernel, but the complexity is not justified.
>> My system is doing basic IO work and provides a web interface for
>> setup and configuration and that is about it. It should not be too
>> taxing.
>>
>> Maybe someone else can share their experience on this.
>>
>> Moussa
>>
>> --- In Fotis Loukos <fotisl@> wrote:
>>> fulatoro wrote:
>>>> Hello, I was attempting to change the HZ setting and recompile the
>>>> kernel but, I was unable to find the option when doing a make
> xconfig.
>>>> I did attempt to modify the .config file manually to set the HZ to
>>>> 1000, but it seems to default back to 100. Any suggestions on
> how to
>>>> do this right?
>>>>
>>>> Moussa
>>>>
>>>>
>>> Hello,
>>> you can change the HZ value at linux/include/asm-arm/param.h. But are
>>> you sure you want to do this? 1000 interrupts per second just for the
>>> timer may be too much. At least for the user applications...
>>>
>>> Fotis
>>>
>
>
>
>
>
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