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    SubjectRe: [v2 2/4] platform: (TS-5500) add GPIO support
    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



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