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SubjectRe: [RFC] Staging:IIO: New ABI
Am 26.01.2010 11:25, schrieb Hennerich, Michael:
>> From: Dmitry Torokhov []
>> On Tue, Jan 26, 2010 at 09:55:45AM +0000, Hennerich, Michael wrote:
>>>> From: Dmitry Torokhov []
>>>> On Fri, Jan 22, 2010 at 04:31:12PM -0800, Greg KH wrote:
>>>>> On Fri, Jan 22, 2010 at 04:14:15PM -0800, Dmitry Torokhov wrote:
>>>>>> On Fri, Jan 22, 2010 at 12:47:18PM -0800, Greg KH wrote:
>>>>>>> On Wed, Jan 20, 2010 at 04:53:21PM +0000, Jonathan Cameron
> wrote:
>>>>>>>> I am not aware of these. Could you direct me to the current
> api? Also note that these
>>>>>>>> aren't the actual alarms, merely a means of enabling the
> relevant event on the related
>>>>>>>> event character device.
>>>>>>> Hm, I thought we had an accelerator interface somewhere...
>>>>>> Nope. And I am also interested in this since I am sittign on a
> bunch of
>>>>>> accelerometers, magnetometers, etc drivers that are trying to
> plug into
>>>>>> input sysbsystem and quite unsure what to do with them.
>>>>>> It was OK whch HDAPS and friends when they were using input for
>>>>>> secondary, toyish purposes, but these new drivers trying to use
> input
>>>>>> devnts as primary API and I am unsure if it is the best
> solution.
>>>>>> Accelerometer might be used as an input device but not always an
> input
>>>>>> device.
>>>>> Yeah, I see it using a joystick interface, which might be
> acceptable for
>>>>> "toy" devices like you say.
>>>>> But for "real" ones, we should do something else.
>>>>> Maybe, for devices that are going to be used by, like the
> "toy"
>>>>> ones, we stick with the current input interface, but for others,
> we use
>>>>> a "real" interface, probably through hwmon, so that users can get
> the
>>>>> real data out in a consistant manner.
>>>> I'd rather have all of them use real interface and then have a
> bridge
>>>> to input module to enable toyish mode (unless the device in question
>>>> is really truly an input device).
>>>> --
>>>> Dmitry
>>> I really don't see that hwmon provides facilities like input/evdev
>>> does. Queuing of events with time stamping and multiple reader
>>> support.
>> I understand that using evdev might be very convenient but I still
>> believe that input should be used for human interfaces, not for generic
>> data acquisition. The idea is that userpsace consumers should be able
> to
>> query device's capabilities and based on those capabilities be able to
>> classify and properly handle the device. Now it all breaks when we get
>> random hardware using EV_ABS/ABS_* for delivering some datastream that
>> has nothing to do with coordinates.
> Acceleration in X,Y,Z translates pretty well in what joysticks deliver.

But it's not only about accelerometers here. We also have gyros,
magnetometers, pressure sensors and generic ADCs.

>>> The adxl34x accelerometer driver for example is really
>>> intended to be a input device. Send EV_KEY for x,y,z_TAP detections,
>>> send EV_KEY for 3D orientation sensing, and EV_ABS for acceleration.
>>> With very minor platform data customization you can use this device
>>> for game controls or GUI interaction. A few examples include digital
>>> picture frames, ebook readers, etc.
>> I see. However, can it be reasonably used for other purposes?
> Well - it depends. Some applications for Accelerometers also include:

> Personal navigation devices
(low to mid data rate)

> Hard disk drive (HDD) protection
(only alerts)

> Safety
(probably low data rate)

What we want with IIO is a common high performance interface to these
devices. That's why we have ring buffers in the kernel. Possible
applications are robotics, precise navigation, data aquisition, etc.

Dipl.-Inf. Manuel Stahl
Fraunhofer-Institut für Integrierte Schaltungen IIS
- Leistungsoptimierte Systeme -
Nordostpark 93 Telefon +49 (0)911/58061-6419
90411 Nürnberg Fax +49 (0)911/58061-6398
fn:Manuel Stahl
tel;work:+49 911 58061-6419

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