Re: [PATCH PREEMPT_RT]: On AT91 ARM: GPIO Interrupt handling can/will stall forever

[Steven Rostedt <rostedt@goodmis.org>]

On Wed, 28 Nov 2007, Daniel Walker wrote:

>
> Ignoring the ARM side of things for a sec, handle_simple_irq() will
> mask() the interrupt in the special case that an interrupt is already in
> the processes of being handled.. handle_simple_irq() also unmasks when
> it finishes handling an interrupt (something real time adds for some
> reason) ..
>
> In terms of threading the irq everything is the same except there is no
> unmask() call when the thread finishes ..
>

OK, to be honest, I never fully understood the concept of this
"simple_irq". I figured it was because of the ARM architecture.

Your arguments seem reasonable and you are probably correct. But I didn't
write this code, nor do I understand it, and before I go ahead and change
it, I'll wait to hear input from Thomas. Hopefully, he'll be back soon.

Perhaps my confusion about the simple_irq part is from the bug you are
trying to fix. I've been confused by why it was different ;-)

-- Steve

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