From: "H. Peter Anvin" <hpa@zytor.com>
To: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>,
x86@kernel.org,
Jerome Oufella <jerome.oufella@savoirfairelinux.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org
Subject: Re: [v2 2/4] platform: (TS-5500) add GPIO support
Date: Tue, 30 Aug 2011 11:43:33 -0700 [thread overview]
Message-ID: <4E5D2F55.2000608@zytor.com> (raw)
In-Reply-To: <20110830143928.4696ec2a@v0nbox>
On 08/30/2011 11:39 AM, 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?
>
Wrapping an atomic operation in a mutex makes no sense no matter how you
slice it...
-hpa
next prev parent reply other threads:[~2011-08-30 18:44 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
2011-08-30 18:43 ` H. Peter Anvin [this message]
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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