From: Mark Brown <broonie@opensource.wolfsonmicro.com>
To: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Cc: x86@kernel.org,
Jerome Oufella <jerome.oufella@savoirfairelinux.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
linux-kernel@vger.kernel.org
Subject: Re: [v2 2/4] platform: (TS-5500) add GPIO support
Date: Tue, 30 Aug 2011 19:41:32 +0100 [thread overview]
Message-ID: <20110830184132.GR2061@opensource.wolfsonmicro.com> (raw)
In-Reply-To: <20110830143928.4696ec2a@v0nbox>
On Tue, Aug 30, 2011 at 02:39:28PM -0400, Vivien Didelot wrote:
> On Mon, 29 Aug 2011 23:11:33 +0100,
> Mark Brown <broonie@opensource.wolfsonmicro.com> wrote:
> > On Fri, Aug 26, 2011 at 07:40:25PM -0400, Vivien Didelot wrote:
> > > + bitno = line_to_bit_map[offset];
> > > + mutex_lock(&drvdata->gpio_lock);
> > > + byte = inb(ioaddr);
> > > + mutex_unlock(&drvdata->gpio_lock);
> > Do you really need the lock to do a read?
> Is there any chance for this function to be preempted before reading the
> register, allowing a call to ts5500_gpio_direction_output to occur
> before ts5500_gpio_get is completed?
Yes, but if that happens the mutex isn't going to help at all as you can
also be prempted before taking the mutex or after dropping it (or before
or after the function call itself...).
next prev parent reply other threads:[~2011-08-30 18:41 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-26 23:40 [v2 0/4] Support for the TS-5500 platform Vivien Didelot
2011-08-26 23:40 ` [v2 1/4] platform: (TS-5500) add base support Vivien Didelot
2011-08-26 23:40 ` [v2 2/4] platform: (TS-5500) add GPIO support Vivien Didelot
2011-08-29 22:11 ` Mark Brown
2011-08-30 5:36 ` H. Peter Anvin
2011-08-30 11:00 ` Mark Brown
2011-08-30 14:49 ` Vivien Didelot
2011-08-30 15:12 ` Mark Brown
2011-10-12 16:41 ` Linus Walleij
2011-10-13 3:31 ` Grant Likely
2011-08-30 18:39 ` Vivien Didelot
2011-08-30 18:41 ` Mark Brown [this message]
2011-08-30 18:43 ` H. Peter Anvin
2011-08-30 21:12 ` Vivien Didelot
2011-10-12 15:35 ` Ingo Molnar
2011-10-14 6:14 ` Ingo Molnar
2011-10-15 14:29 ` Vivien Didelot
2011-08-26 23:40 ` [v2 3/4] platform: (TS-5500) add LED support Vivien Didelot
2011-08-29 22:16 ` Mark Brown
2011-08-30 5:37 ` H. Peter Anvin
2011-08-30 21:14 ` Vivien Didelot
2011-08-30 21:15 ` Mark Brown
2011-08-30 21:17 ` H. Peter Anvin
2011-08-30 21:56 ` Vivien Didelot
2011-08-30 22:04 ` H. Peter Anvin
2011-08-31 20:01 ` Vivien Didelot
2011-10-12 15:34 ` Ingo Molnar
2011-10-15 14:42 ` Vivien Didelot
2011-10-15 14:56 ` Ingo Molnar
2011-11-16 5:41 ` Ingo Molnar
2011-11-16 12:50 ` Mark Brown
2011-10-26 15:41 ` Ingo Molnar
2011-11-17 15:27 ` Vivien Didelot
2011-08-26 23:40 ` [v2 4/4] platform: (TS-5500) add ADC support Vivien Didelot
2011-08-29 22:13 ` Mark Brown
2011-09-12 7:28 ` [v2 0/4] Support for the TS-5500 platform Pavel Machek
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