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

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Message-ID: <3efb10970711260531x5e9f05acgfabdfa885a220192@mail.gmail.com>
Date:	Mon, 26 Nov 2007 14:31:46 +0100
From:	"Remy Bohmer" <linux@...mer.net>
To:	"Ingo Molnar" <mingo@...e.hu>,
	"Steven Rostedt" <rostedt@...dmis.org>
Cc:	"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>
Subject: [PATCH PREEMPT_RT]: On AT91 ARM: GPIO Interrupt handling can/will stall forever

Hello,

I use 2.6.23.1-rt5 on the Atmel AT91 series.
Interrupt threading on Preempt-RT and ARM works fine, except for
(edge-triggered) GPIO interrupts. There is a problem when a new
interrupt arives while the interrupt thread is handling the previous
interrupt. If this occurs the interrupt handling stalls forever.

This is caused by a unbalanced interrupt mask/unmask problem in the kernel.
The attached patch fixes this. More information about this problem is
documented inside the patch itself.

This patch is meant for Preempt-RT only.

Kind Regards,

Remy Bohmer

View attachment "fix-gpio-irq-stalling-bug.patch" of type "text/x-patch" (2062 bytes)