From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Leon Woestenberg <leon.woestenberg@gmail.com>
Cc: LAK <linux-arm-kernel@lists.arm.linux.org.uk>,
Linux Kernel list <linux-kernel@vger.kernel.org>
Subject: Re: Locking in the (now generic) GPIO infrastructure?
Date: Fri, 6 Jun 2008 09:52:00 +0100 [thread overview]
Message-ID: <20080606085200.GC2765@flint.arm.linux.org.uk> (raw)
In-Reply-To: <c384c5ea0806040400j35236d5fo3854ce2ed30cd755@mail.gmail.com>
On Wed, Jun 04, 2008 at 01:00:19PM +0200, Leon Woestenberg wrote:
> include/asm-arm/arch-ixp4xx/platform.h:
> static inline void gpio_line_set(u8 line, int value)
> {
> if (value == IXP4XX_GPIO_HIGH)
> *IXP4XX_GPIO_GPOUTR |= (1 << line);
> else if (value == IXP4XX_GPIO_LOW)
> *IXP4XX_GPIO_GPOUTR &= ~(1 << line);
> }
>
> Under a Linux kernel where multiple drivers are accessing GPIO, the
> latter does not seem safe against preemption (assuming the memory
> read-modify-write is not atomic).
or even interrupts.
> Shouldn't GPIO access be protected against concurrent access here?
Definitely. It's certainly buggy as currently stands.
next prev parent reply other threads:[~2008-06-06 8:52 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-06-04 11:00 Leon Woestenberg
2008-06-06 8:52 ` Russell King - ARM Linux [this message]
2008-06-06 10:28 ` Ben Dooks
2008-06-06 12:53 ` David Brownell
2008-06-06 19:23 ` Leon Woestenberg
2008-06-06 20:13 ` David Brownell
2008-06-07 11:52 ` Mikael Pettersson
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