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    SubjectRE: [PATCH 1/3] irq: If an IRQ is a GPIO, request and configure it
    Mark Brown wrote at Thursday, August 04, 2011 6:02 PM:
    > On Thu, Aug 04, 2011 at 05:00:18PM -0600, Stephen Warren wrote:
    >
    > > + } else {
    > > + gpio = irq_to_gpio(irq);
    > > + if (gpio_is_valid(gpio)) {
    > > + ret = gpio_request(gpio, new->name);
    > > + if (ret < 0)
    > > + goto out_mask;
    > > + ret = gpio_direction_input(gpio);
    > > + if (ret < 0)
    > > + goto out_mask;
    > > + }
    >
    > If you treat failures as an error what happens when a driver is using a
    > GPIO as both an interrupt and a GPIO? For example a driver which
    > monitors the level on a GPIO and uses edge triggered IRQs to be notified
    > of state changes.

    Well, things break. This is essentially the problem I was describing in
    the PATCH 0 email, just with a slightly different motivation.

    I suppose that an alternative here would be to simply ignore any errors
    from gpio_request. This might have the benefit of removing the need for
    the other two patches I posted in the series. However, it seems a little
    dirty; one benefit of the IRQ code calling gpio_request and honoring
    errors would be to detect when some completely unrelated code had a bug
    and had called gpio_request on the GPIO before. Such detection would be
    non-existent if we don't error out on gpio_request. Perhaps some mechanism
    is needed to indicate that the driver has explicitly already called
    gpio_request for a legitimate shared purpose, and only then ignore
    errors?

    --
    nvpublic



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