[Letux-kernel] [PATCH] Revert "Input: bma150 - avoid binding to bma180 if IIO bma180 driver present" and "Input: bma150 - extend chip detection for bma180"

H. Nikolaus Schaller hns at goldelico.com
Wed Apr 5 21:16:28 CEST 2017

> Am 01.04.2017 um 18:46 schrieb Dmitry Torokhov <dmitry.torokhov at gmail.com>:
> On Sat, Apr 01, 2017 at 04:59:26PM +0200, Hans de Goede wrote:
>> Hi,
>> On 01-04-17 16:44, H. Nikolaus Schaller wrote:
>>> This reverts commit baf28d91e7b1 ("Input: bma150 - avoid binding to bma180 if IIO bma180 driver present")
>>> and commit ef3714fdbc8d ("Input: bma150 - extend chip detection for bma180")
>>> Rationale: initially (2012) the GTA04 device using a bma180 chip simply refereced
>>> the bma150 platform driver in its board file [1] which happened to work in all
>>> scenarios that were tested.
>>> When conversion to DT started (2014), we needed to make the driver be still
>>> recognised. Hence we introduced the compatibility to the bma180 chip in
>>> Linux 3.15-rc5 [2] without further checks if it is really 100% compatible. This
>>> worked flawlessly for years with the GTA04 device.
>>> Recently (2016), Hans de Goede pointed out that the chips are not as similar
>>> as they appeared and the driver works with the bma180 for the GTA04 only
>>> by good luck. He proposed to remove the bma180 support completely [3], but
>>> we still did need it until we have a replacement. Thus, a condifional compile
>>> was added.
>>> We have now developed a generic iio-input-bridge which works with any 2 or
>>> 3 axis iio based accelerometer. It has been tested on GTA04 and Pyra and
>>> works as expected. Therefore we can remove the bma180 support from this
>>> driver completely. User-space API compatibility can be restored by using the
>>> iio-input-bridge.
>>> Maybe it is time to convert the bma150 driver to iio as well and retire the
>>> accelerometer input drivers completely but this is a different story and task.
>>> [1]: https://github.com/neilbrown/linux/blob/gta04/3.2.y/arch/arm/mach-omap2/board-omap3gta04.c#L976
>>> [2]: https://patchwork.kernel.org/patch/3961171/
>>> [3]: https://patchwork.kernel.org/patch/9325481/
>>> Signed-off-by: H. Nikolaus Schaller <hns at goldelico.com>
>> Looks good to me:
>> Reviewed-by: Hans de Goede <hdegoede at redhat.com>
> Changed subject slightly (we are not reverting because patches were
> defective, we are removing support for bma180), and applied.

Just noticed: the subject in linux-next has a typo:
Should IMHO be "Input: bma150 - remove support for bma180"



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