Re: [PATCH] iio: light: acpi-als: Report data as processed rather than raw
From: Gabriele Mazzotta
Date: Tue Jan 12 2016 - 10:27:41 EST
2016-01-11 20:18 GMT+01:00 Jonathan Cameron <jic23@xxxxxxxxxx>:
> On 09/01/16 17:27, Marek Vasut wrote:
>> On Saturday, January 09, 2016 at 05:31:24 PM, Jonathan Cameron wrote:
>>> On 07/01/16 15:21, Gabriele Mazzotta wrote:
>>>> As per the ACPI specification (Revision 5.0) , the data coming
>>>> from the sensor represent the ambient light illuminance reading
>>>> expressed in lux. Use IIO_CHAN_INFO_PROCESSED instead of
>>>> IIO_CHAN_INFO_RAW to signify that the data are pre-processed.
>>>>  http://www.acpi.info/DOWNLOADS/ACPIspec50.pdf
>>>> Signed-off-by: Gabriele Mazzotta <gabriele.mzt@xxxxxxxxx>
>>> Hm. Whilst it's a fix in a sense, the original didn't really 'break'
>>> the ABI so I worry a little that this change may break others.
>>> Irritating as it is, perhaps we should keep the _RAW and add _PROCESSED
>>> (which will then be exactly the same value).
>>> We'll also then need a comment in the code, that leaving the _RAW
>>> elements was for ABI compatibility.
>>> What do others think?
>> I'm not an IIO guru, but this does sound sensible. Do you know if any userland
>> code which actually uses the ACPI ALS already ?
> It's more than likely as Gnome at least supports using them to control screen
> brightness. Hopefully that code is able to cope with the correct ABI though as
> well as the old one. Anyhow, we seem to have a reasonable consensus.
I looked into this and Gnome uses iio-proxy-sensor to handle iio
devices. As of now it, only looks for in_illuminance_input, so it
currently doesn't work with acpi-als. I've also found a bug report 
of an acpi-als user stating the same.
> Gabriele, are you happy to do a version of the patch with the _RAW version
> left along side your _PROCESSED version and a comment saying that it is for
> compatibility only?
>> Best regards,
>> Marek Vasut
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