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Sender: Grant Likely <glikely@secretlab.ca>
Date: Tue, 27 Sep 2011 12:29:12 -0600
From: Grant Likely <grant.likely@secretlab.ca>
To: Felix Radensky <felix@embedded-sol.com>
Subject: Re: Handling multiple GPIO controllers in 8xxx GPIO driver
Message-ID: <20110927182912.GA3994@ponder.secretlab.ca>
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On Tue, Sep 27, 2011 at 04:59:28PM +0300, Felix Radensky wrote:
> Hi,
> 
> Looks like  8xxx GPIO driver cannot properly handle interrupts
> when multiple GPIO controllers exist in the system.
> 
> On Freescale P1022 there are 3 GPIO controllers. All 3 use
> the same interrupt line, internal interrupt 31. If all controllers
> are defined in device tree set_irq_chained_handler() is invoked
> 3 times with same  hardware irq number. The result is interrupt
> storm,  mpc8xxx_gpio_irq_cascade() is invoked indefinitely.
> 
> What would be the best way to fix the problem ?

The solution is to make the gpio driver register as a regular
interrupt handler, and not as a chained handler.

g.