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List:       linux-arm-kernel
Subject:    Re: pending interrupts
From:       Marc Singer <elf () buici ! com>
Date:       2004-09-14 13:55:32
Message-ID: 20040914135532.GA16155 () buici ! com
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On Tue, Sep 14, 2004 at 11:47:08AM +0200, Hinko Kocevar wrote:
> Russell King - ARM Linux wrote:
> 
> >Why do you think you don't need this?
> 
> I coded driver for rotary pulse generator (RPG)- potentiometer like 
> piece of hardware that connects to two gpio pins, and generates pulses 
> on both pins according to direction being rotated. For detection of 
> pulses and consequently detection of turning direction I used those two 
> pins as interrupts. It works fine, but as I said, if interrupts are 
> pending there are some unwanted effects. Eg. Turning the RPG causes 
> value displayed on LCD to change, what I don't want is value changing 
> after I stop turning it - which is the effect of pending interrupts 
> accumulated.

Sounds like a latency problem and not an issue with pending
interrupts.

If, for example, the interrupt is only used to update a value and it
can return very quickly (think microseconds), then there ought not to
be a problem.  In other words, separate the interrupt handler from the
display and use another mechanism to refresh the display when the pot
value changes.

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