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    SubjectRe: [PATCH v2 1/1] input: add driver for Bosch Sensortec's BMA150 accelerometer
    On Thu, Jun 23, 2011 at 04:36:31PM +0100, Alan Cox wrote:
    > > +
    > > +
    > > +What: /sys/bus/i2c/devices/<busnum>-<devaddr>/value
    > > +Date: May 2011
    > > +Contact: Eric Andersson <eric.andersson@unixphere.com>
    > > +Description: This is used to get the current acceleration values for each
    > > + axis. The values are represented as (x,y,z), where each axis can
    > > + hold a value between -512 and 511.
    > > +
    > > + Reading: returns the current acceleration values.
    >
    > This was nacked in the bma023 driver by the IIO folks - and Dmitry
    > pointed out you can do this without a sysfs hack. The trick is to do an
    > initial poll in input_open at which point the ioctl query for the
    > position will have data that is current and open/ioctl/close works and
    > providing we go nail that into other drivers that need that kind of use
    > the API is generic and input event based.
    >

    Right, I think the patch below will do what is needed for all polled
    devices.

    Thanks.

    --
    Dmitry


    Input: polldev - immediately poll device upon opening

    To allow open/ioctl(EVIOCGABS)/close use pattern for polled devices read
    the device in context of open() call instead of offloading the first read
    to a workqueue. This will ensure that once call to open() returns device
    would have cached reasonably recent axis values that can be retrieved via
    appropriate ioctl.

    Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
    ---

    drivers/input/input-polldev.c | 6 ++++--
    1 files changed, 4 insertions(+), 2 deletions(-)


    diff --git a/drivers/input/input-polldev.c b/drivers/input/input-polldev.c
    index b1aabde..b253973 100644
    --- a/drivers/input/input-polldev.c
    +++ b/drivers/input/input-polldev.c
    @@ -49,8 +49,10 @@ static int input_open_polled_device(struct input_dev *input)
    dev->open(dev);

    /* Only start polling if polling is enabled */
    - if (dev->poll_interval > 0)
    - queue_delayed_work(system_freezable_wq, &dev->work, 0);
    + if (dev->poll_interval > 0) {
    + dev->poll(dev);
    + input_polldev_queue_work(dev);
    + }

    return 0;
    }

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