Steve Papacharalambous wrote:
>
> Philip N Daly wrote:
> >
> > Content-MD5: fVT3+tdeWfB8vwdyUSaZXQ==
> >
> > Hi,
> >
> > Not specifically a RTL/RTAI question but does anyone know how to
> > "sleep" in a kernel module? Not something I want to do very often
> > but I have a need right now. udelay appears to crash my kernel.
> >
> > Ta,
> >
> > +==================================================================+
> > Phil Daly, NOAO/AURA, 950 N. Cherry Avenue, Tucson AZ 85719, U S A
> > E-mail: [EMAIL PROTECTED] V-mail: (520) 318 8438 Fax: (520) 318 8360
> >
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> > http://www.rtlinux.org/~rtlinux/
>
> Hi Phil,
>
> For periods greater than a timer tick you can set current->timeout and
> sleep on a wait queue. The timeout value is compared with jiffies every
> time the scheduler runs, and if it is smaller than or equal to the
> current time the scheduler will wake the process. For example:
>
> unsigned long time_delay;
>
> time_delay = jiffies + my_delay;
>
> current->timeout = time_delay;
> current->state = TASK_INTERRUPTIBLE;
> schedule();
> current->timeout = 0;
>
> An alternative to this is to use kernel timers to dispatch a function at
> some time in the future. For example:
>
> unsigned long time_delay;
> struct timer_list my_timer;
>
> init_timer(&my_timer);
> my_timer.function = <function to be called>;
> my_timer.data = <any data to pass to the function>;
> my_timer.expires = jiffies + time_delay;
> add_timer(&my_timer);
>
> For very short delays use the kernel function udelay:
>
> #include <linux/udelay.h>
> void udelay(unsigned long usecs);
>
> Remember that udelay is a busy waiting function, so other tasks cannot
> run during the time lapse. The suggested maximum for this function is 1
> millisecond.
>
> For more information on this topic Chapter 6 of Linux Device Drivers by
> Rubini has some very useful details,
>
> Best regards,
>
> Steve
>
You talk about modules not in the rtl environment, did you?
I use the function rtl_delay in my module instead, isn't this ok?
Heinz
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