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

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Date:	Wed, 28 Nov 2007 15:43:49 +0100
From:	"Remy Bohmer" <linux@...mer.net>
To:	"Kevin Hilman" <khilman@...sta.com>
Cc:	"Daniel Walker" <dwalker@...sta.com>,
	"Ingo Molnar" <mingo@...e.hu>,
	"Steven Rostedt" <rostedt@...dmis.org>,
	"ARM Linux Mailing List" <linux-arm-kernel@...ts.arm.linux.org.uk>,
	RT <linux-rt-users@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	"Thomas Gleixner" <tglx@...utronix.de>
Subject: Re: [PATCH PREEMPT_RT]: On AT91 ARM: GPIO Interrupt handling can/will stall forever

Hello Kevin,

Just copied your mail to the list, maybe your solution is also worth looking at.

Remy

> I had a similar issue when using the chained GPIO interrupts on OMAP
> under PREEMPT_RT.
>
> I believe the chained handler itself is supposed to be doing the
> ack/unmask instead of the simple_handler.
>
> However, currently there is no way for the chained handler to know
> when the threaded handler has acutally run.  So the way I fixed this
> was to have the simple handler call the chip->end hook so that the
> chained handler could do the ack/unmask after the threaded handler has
> actually run.
>
> I've been using this against the -rt patch since 2.6.21, and submitted
> and RFC a while back, but got no comments.
>
> This patch is against 2.6.24-rc2-rt1.
>
> Signed-off-by: Kevin Hilman <khilman@...sta.com>
>
> diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
> index b35d209..2f9e09e 100644
> --- a/kernel/irq/manage.c
> +++ b/kernel/irq/manage.c
> @@ -661,6 +661,8 @@ static void thread_simple_irq(irq_desc_t *desc)
>                         note_interrupt(irq, desc, action_ret);
>         }
>         desc->status &= ~IRQ_INPROGRESS;
> +       if (desc->chip->end)
> +               desc->chip->end(irq);
>  }
>
>  /*
>
>
>
>
-
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