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    SubjectRe: LIS331DLH accelerometer driver, IIO or not?
    On Thu, May 24, 2012 at 09:29:53PM -0700, Darren Hart wrote:
    > I'm working to enable the LIS331DLH accelerometer on the Fish River
    > Island II embedded atom development kit.
    > This device is attached to an i2c bus implemented in a CPLD (complex
    > programmable logic device) integrated on the compute module. I found an
    > IIO driver for the device written for 2.6.34. I've rewritten most of the
    > driver to work with the 3.2 kernel's IIO subsystem (and had planned to
    > next port it all the way to git HEAD and push it upstream).
    > However, I've since stumbled across a couple of things which cloud the
    > issue for me.
    > First, Carmine Iascone submitted a driver (driver/misc, not iio) for the
    > LIS331DLH back in Nov 2010.
    > It was suggested that this driver be merged with the existing lis3lv02d
    > driver which listed support for a similar chip in the header, LIS331DL,
    > but it also lists LIS331DLF as not supported. The current git HEAD still
    > does not list LIS331DLH, and there is not a compatible register map in
    > the header.
    > Second, I came across the following TI document for porting the
    > LIS331DLH driver for Android:
    > This references a lis331dlh.c driver which I do not find in Linus' git
    > repository nor in linux-next.
    > So there are 3 ways I can go about this, and I'd appreciate any
    > direction on which would be the most acceptable for merging upstream.
    > 1) Continue with my IIO version. This subsystem seems well suited to the
    > accelerometer. The iio_chan_spec simplifies the task of exposing the
    > event capabilities of the device, which the drivers/misc/lis3lv02d
    > driver mostly glosses over. It only supports events on free-fall for
    > example, while with IIO it is straight forward to enable interrupts for
    > rising and/or falling thresholds for each axis independently.
    > 2) Attempt to merge Carmine's drivers/misc/lis331dlh driver with the
    > existing lis3lv02d driver as suggested in the thread mentioned above.
    > This driver isn't as fully functional.
    > 3) Try and dig up the lis331dlh driver referenced in the TI document and
    > work to get that upstream. Like option 2, this driver is not likely to
    > be as configurable as the IIO driver.
    > I am more interested in enabling people to do bizarre and interesting
    > things with the device, so I'm leaning toward continuing with my IIO
    > implementation.

    Make it an IIO driver and then we can delete the misc driver, which
    shouldn't have snuck in there in the first place :)

    greg k-h

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