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Cc: Grant Likely <grant.likely@secretlab.ca>, linux-kernel@vger.kernel.org,
        alexander.stein@systec-electronic.com, qi.wang@intel.com,
        yong.y.wang@intel.com, joel.clark@intel.com, kok.howg.ewe@intel.com,
        toshiharu-linux@dsn.okisemi.com
From: Jean-Francois Dagenais <jeff.dagenais@gmail.com>
Subject: gpio-pch: does not honour IRQF_ONESHOT?
Date: Thu, 8 Dec 2011 14:37:31 -0500
To: Tomoya MORINAGA <tomoya-linux@dsn.okisemi.com>
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Hello all,

I am using the interrupt function of gpio-pch.c. I have an adp5588 who's interrupt line goes into one of the
GPIO lines of a EG20T.

I have a patch (not yet submitted to lkml) which lets the platform control the IRQ flags for the chip. I had to
do this to allow the IRQ line to be shared. I used IRQF_SHARED | IRQF_ONESHOT | IRQF_TRIGGER_LOW.

Unfortunately, since all of the handling of the adp5588 is done in a thread function, the interrupt stays low
between the moment the hard handler is run and the 5588 function is run. Since pch_gpio_handler clears
the interrupt status right away, I get an interrupt storm for the pch_gpio_handler function.

the line that does "iowrite32(BIT(i), &chip->reg->iclr);" right before calling generic_handle_irq should be
executed only after the corresponding nested ISR has run it's thread function.

I am open to patching this and submitting, but I would like some pointers before I dive in.

Thanks for the help!
(and thanks Tomoya for the interrupt support ;)

On Jul 20, 2011, at 20:19, Tomoya MORINAGA wrote:

> 
> Signed-off-by: Tomoya MORINAGA <tomoya-linux@dsn.okisemi.com>
> ---
> drivers/gpio/Kconfig    |    1 +
> drivers/gpio/gpio-pch.c |  187 +++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 188 insertions(+), 0 deletions(-)
> ...