Override timer interrupt

2 messages, 2 authors, 2007-10-12 · open the first message on its own page

Override timer interrupt

From: Rune Torgersen <hidden>
Date: 2007-10-12 20:49:04

Is there an easy way to use something other than the decrementer for the
timer interrupt?

Reason i'm asking is tha t on our board, the decrementer cannot be
divided to 1khz evenly, so we have rounding errors for time, but we do
have a 1KHz timer interrupt from an FPGA that is source of a T1 clock.

Right now I let the decrementer interrupt do nothing, and made my own
timer interrupt handler that calls the stuff the timer_interrupt usually
does.=20

This works, but there are some instability (ie unexplained hangs) that
showed up when I did this.

Re: Override timer interrupt

From: Mark A. Greer <hidden>
Date: 2007-10-12 21:32:32

On Fri, Oct 12, 2007 at 03:49:02PM -0500, Rune Torgersen wrote:
Is there an easy way to use something other than the decrementer for the
timer interrupt?

Reason i'm asking is tha t on our board, the decrementer cannot be
divided to 1khz evenly, so we have rounding errors for time, but we do
have a 1KHz timer interrupt from an FPGA that is source of a T1 clock.

Right now I let the decrementer interrupt do nothing, and made my own
timer interrupt handler that calls the stuff the timer_interrupt usually
does. 

This works, but there are some instability (ie unexplained hangs) that
showed up when I did this.
I just responded to you on -embedded with this:

"Check out the clocksource stuff.  It let's you set up numerous clock
 sources and set the rating of each one.  You can start looking in
 arch/powerpc/kernel/time.c for example code."

Mark
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