Re: [PATCH V4 6/7] iio: mma8452: Add highpass filter configuration.

[Jonathan Cameron <jic23@kernel.org>]

On 18/05/15 09:17, Martin Fuzzey wrote:
> On 17/05/15 11:48, Jonathan Cameron wrote:
>> On 13/05/15 11:26, Martin Fuzzey wrote:
>>> Allow the cutoff frequency of the high pass filter to be configured.
>>>
>>> Signed-off-by: Martin Fuzzey <mfuzzey@parkeon.com>
>> Oops, I missed in patch 4 that you'd added the event_spec entry for the highpass
>> filter but not the support to actually read it (which is here).
> Ah true, good catch
> 
>> I'll back out back to patch 4.  Could you repost with that sorted out.
> ok
> 
>> Also, if (as I think is happening here) we have a filter applied to all
>> the data that is read from a channel (including it's events) then we normally
>> only have the attribute for the iio_chan_spec rather than the event spec
>> as well.
>>
>> Anything that is in the parent directory is also assumed to apply to the
>> event directory if not overridden (by it being in both) as we could have
>> a pipeline in the device with seperate filters for the event detector and
>> the main data flow (not true here?)
>>
>> Hence, please drop the event version unless I have missunderstood what
>> you are doing with the hardware.
>>
>> It's fine to leave the abi docs in place however as they are correct even
>> if we don't normally introduced them until there is a driver using them.
> 
> The hardware has one filter and two enable bits (one for the data and one for the event)
> It is thus possible to read unfiltered data but have the filter applied for the events.
> 
> We discussed this in revision 2 of the series.
> https://www.marc.info/?l=linux-iio&m=140803621414813&w=2
> 
> I thought we agreed in the above discussion to represent this as two 3db frequencies with 0 meaning disable.
> I did that for V3 of the series.
> 
Hmm.  thought I'd replied to this from my phone the other day..
Just in case that never went anywhere, this is fine and just
my memory failing me!  

Jonathan