PPC405GP: Spurious interrupt during handing level triggered interrupts

Kenneth Johansson kenneth.johansson at etx.ericsson.se
Thu Mar 11 03:30:14 EST 2004

On Tue, 2004-03-09 at 23:58, listmember at orkun.us wrote:

> Now, to prevent the second spurious branching, I used ack_irq() call
> (actuall macro) to manually ack the interrupt (before enabling interrupts
> again in ioctl). It works this way.
> Is this OK to use or is there a preferred way to do this?

That's mainly what I do also.

I had this comment in the cvs log.
The status register was not reset by enable_irq so it
remembered the last one resulting in every interrupt
getting reported twice.
and the code that I used was

/* We have to do this manually as enable do not do this for us */
void mask_SR(int dev_irq){

	int bit;
	bit = (dev_irq-17) +25;

	mtdcr(DCRN_UIC_SR(UIC0), (1 << (31 - bit)));
basically parts of what irq_ack would do (dev_irq is a privat number
local to this driver)

Perhaps the enable code should reset this bit also?? everyone that dose
this type of userspace driver is going to hit this problem.

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