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    Subject[PATCH] regulator: pass voltage when calling notifier for change
    Date
    The notified call back does pass the voltage that has
    changed when calling the notifier callback. This makes
    it impossible to know what to do. Pass the data
    parameter (voltage) to the notifier.

    A call to regulator_get_voltage cannot be made by the
    receiver of the notifier since the mutex is held by
    the regulator code and the call is blocked. Deadlock
    occurs.

    This code was tested on a slightly earlier version of
    linux where it was used to adjust the chip pad voltage
    when doing SD vccq signaling for SDXC cards.

    Signed-off-by: Philip Rakity <prakity@marvell.com>
    ---
    drivers/regulator/core.c | 15 ++++++++++-----
    1 files changed, 10 insertions(+), 5 deletions(-)

    diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
    index e70dd38..f3d66d6 100644
    --- a/drivers/regulator/core.c
    +++ b/drivers/regulator/core.c
    @@ -1916,11 +1916,16 @@ static int _regulator_do_set_voltage(struct regulator_dev *rdev,
    udelay(delay);
    }

    - if (ret == 0)
    - _notifier_call_chain(rdev, REGULATOR_EVENT_VOLTAGE_CHANGE,
    - NULL);
    + if (ret == 0) {
    + int voltage;

    - trace_regulator_set_voltage_complete(rdev_get_name(rdev), selector);
    + voltage = _regulator_get_voltage(rdev);
    + if (voltage >= 0)
    + _notifier_call_chain(rdev,
    + REGULATOR_EVENT_VOLTAGE_CHANGE,
    + (void *)voltage);
    + }
    + trace_regulator_set_voltage_complete(rdev_get_name(rdev), ret);

    return ret;
    }
    @@ -2405,7 +2410,7 @@ static void _notifier_call_chain(struct regulator_dev *rdev,
    unsigned long event, void *data)
    {
    /* call rdev chain first */
    - blocking_notifier_call_chain(&rdev->notifier, event, NULL);
    + blocking_notifier_call_chain(&rdev->notifier, event, data);
    }

    /**
    --
    1.7.0.4


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