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    SubjectRe: [PATCH v2] gpiolib: allow poll(2) on gpio value
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    On Thu, Jul 2, 2009 at 21:57, David Brownell<david-b@pacbell.net> wrote:
    > On Thursday 02 July 2009, Jani Nikula wrote:
    >> > Looks pretty clean.  Comments from anyone else?
    >>
    >> I'd appreciate a kernel side interface to gpio_setup_irq functionality
    >> as well; now gpio_export from kernel won't setup support for poll(2)
    >> nor is there any possibility to do so.
    >
    > I don't understand what you mean by this... there's no
    > file descriptor open at that time, so there's no poll()
    > that could be done.

    I'm trying to say that if you call gpio_export() to create a sysfs
    node, a subsequent poll() in user space won't work because there is no
    irq set up, and sysfs_notify_dirent() won't be called. The patch
    doesn't provide an interface for setting that up from kernel after
    gpio_export() call - it's only possible to set up edge triggering and
    sysfs notify by writing to the "edge" node from user space. That may
    well be deemed sufficient, at least for now, and can be fixed later if
    need be.


    BR,
    Jani.
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