> -----Original Message----- > From: Jonathan Cameron [mailto:jic23@xxxxxxxxxx] > Sent: Sunday, June 21, 2015 1:06 PM > To: Breana, Tiberiu A; linux-iio@xxxxxxxxxxxxxxx > Subject: Re: [PATCH] iio: light: STK3310: un-invert proximity values > > On 17/06/15 12:09, Tiberiu Breana wrote: > > In accordance with the recent ABI changes, STK3310's proximity > > readings should be un-inversed in order to return low values for > > far-away objects and high values for close ones. > > <snip> > > -/* > > - * Maximum PS values with regard to scale. Used to export the 'inverse' > > - * PS value (high values for far objects, low values for near objects). > > - */ > > + > > +/* Estimate maximum proximity values with regard to measurement > > +scale. */ > > static const int stk3310_ps_max[4] = { > > - STK3310_PS_MAX_VAL / 64, > > - STK3310_PS_MAX_VAL / 16, > > - STK3310_PS_MAX_VAL / 4, > > - STK3310_PS_MAX_VAL, > > + STK3310_PS_MAX_VAL / 640, > > + STK3310_PS_MAX_VAL / 160, > > + STK3310_PS_MAX_VAL / 40, > > + STK3310_PS_MAX_VAL / 10 > > }; > What's this change about? All uses of this array as present in this patch have > been removed. It is used elsewhere for parameter sanity checking, but I > can't follow why it now needs to be divided by 10. Indeed, these values are still used in _write_event for setting proximity interrupt threshold values. Truth is, they should have been divided by 10 from the start, but since all values were relative to the pre-defined maximum values, it didn't really matter. I used the higher max values because the readings would sometimes go over the expected range (when I press down on the sensor with my thumb), so the proximity readings became negative. But that shouldn't happen in the case of a real device, as the sensor is covered by at least a screen layer. For the default scale of 0.1 real proximity readings max out at around 6500, roughly a tenth of the maximum theoretical value, as expected. Now that we're using un-inverted measurements, we can't use the same reference values as before - e.g. if the real maximum value is 6500, we can't allow setting a threshold of 30000 - it will never be reached. If you think this change warrants a separate patch, I'll split it. Regards, Tiberiu-- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
