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    SubjectRe: [PATCH RFC 0/3] Implement refcounting for OF GPIO chips
    Anton Vorontsov wrote:
    > Hi all,
    >
    > OF GPIO infrastructure is using dynamic GPIO bases, so it is possible
    > that of_get_gpio()'s returned GPIO number will be no longer valid, or
    > worse, it may point to an unexpected GPIO controller.
    >
    > This scenario is possible:
    >
    > driver A: driver B: driver C:
    > --------- --------- ---------
    > gpiochip_add()
    > gpio = of_get_gpio()
    > gpiochip_remove()
    > gpiochip_add()
    > gpio_request(gpio);
    > gpio_set_value(gpio);
    >
    > That is, driver A assumes that it is working with GPIO from driver B,
    > but in practice it may disappear and driver C will take its GPIO base
    > number, so it will provide the same GPIO numbers.
    >
    > The above situation is hard to trigger, but the issue is there
    > nonetheless, and so needs fixing.


    I tested xilinx gpio driver, heartbeat trigger and access through sysfs
    and I haven't found any problem. There is only small part of code for
    Microblaze and it is the same with PowerPC. If is Ben OK with it, I am
    ok too.

    Thanks,
    Michal


    >
    > Thanks,
    >
    > p.s. The patches are based on top of
    > '[PATCH v2 0/4] OF GPIO integration for I2C/SPI GPIO chips'
    > http://lkml.org/lkml/2010/2/5/243
    >


    --
    Michal Simek, Ing. (M.Eng)
    PetaLogix - Linux Solutions for a Reconfigurable World
    w: www.petalogix.com p: +61-7-30090663,+42-0-721842854 f: +61-7-30090663


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