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    SubjectRe: [PATCH 01/11] misc: inv_mpu primary header file and README file.
    On Thu, Jun 30, 2011 at 07:18:17PM -0700, Nathan Royer wrote:
    > This files defines the userspace interface and how to integrate it into a
    > platform.
    > Signed-off-by: Nathan Royer <>
    > ---
    > This is the first of many patch files for the inv_mpu driver in its current
    > state. This is our first time submitting this driver, so I expect there to be
    > a lot wrong with it, and expect to need to fix many things.
    > The inv_mpu driver attepts to implement a Motion Processing Unit interface. As
    > a unit, an accelerometer, magnetometer, gyroscope, and/or altimiter data is
    > fused together to produce calibrated data and a quaternion.
    > The inv_mpu driver interface is currently implemented as a misc device, but may
    > need to change to include both sysfs attributes and input devices. I think
    > that we will continue to need the ioctl interface, but many of the ioctls can
    > be replace by attributes and/or input devices.
    > The mpu3050 has an i2c master interface designed to control an accelerometer
    > and a Digital Motion Processor (DMP) used to perform sensor fusion on the
    > gyroscope and accelerometer. This data is then read out of the mpu3050 fifo
    > and sent to userspace for distribution and optional propritary processing, such
    > as fusion with a compass to produce a 9 axis quaternion.
    > Some question I have at the start are:
    > 1) Is there a master design or standard interface for Motion Processing
    > devices, specifically ones that do calibration, sensor fusion, and or have a
    > micro-controller to do some of this work.
    > 2) Is there a standard way to integrate user space components with kernel side
    > components.
    > 3) Should data be pushed back to the driver from userspace, and made available
    > as an input device or should it remain as a character device.
    > 4) Can a 4 element quaternion be added to input.h:
    > for <1, i, j, k>
    > 5) Should we instead use a rotation vector as defined in the Android sensor:
    > 6) Are there any other major design concerns?

    Shouldn't you be using the iio subsystem for the kernel/user interface
    as I think it handles most of this for you already, right?

    > 7) Can an input device also have a character device interface for proprietary
    > customization.

    What do you mean by this?

    greg k-h

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