From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-ID: <551C41C0.2050609@linux.intel.com> Date: Wed, 01 Apr 2015 12:06:40 -0700 From: sathyanarayanan kuppuswamy Reply-To: sathyanarayanan.kuppuswamy@linux.intel.com MIME-Version: 1.0 To: Lars-Peter Clausen , Daniel Baluta CC: Jonathan Cameron , Peter Meerwald , "linux-iio@vger.kernel.org" , Srinivas Pandruvada Subject: Re: [PATCH v1 2/3] iio: ltr501: Add interrupt rate control support References: <212b45fac712e84a3cf0bc5955def7d1b683a6bd.1427856701.git.sathyanarayanan.kuppuswamy@linux.intel.com> <551C030E.1090309@metafoo.de> <551C0B95.9080802@metafoo.de> <551C2EC4.1050208@linux.intel.com> <551C2F63.50609@metafoo.de> In-Reply-To: <551C2F63.50609@metafoo.de> Content-Type: text/plain; charset=utf-8; format=flowed List-ID: On 04/01/2015 10:48 AM, Lars-Peter Clausen wrote: > On 04/01/2015 07:45 PM, sathyanarayanan kuppuswamy wrote: >> >> >> On 04/01/2015 08:15 AM, Lars-Peter Clausen wrote: >>> On 04/01/2015 05:02 PM, Daniel Baluta wrote: >>>> On Wed, Apr 1, 2015 at 5:39 PM, Lars-Peter Clausen >>>> wrote: >>>>> On 04/01/2015 04:04 PM, Daniel Baluta wrote: >>>>> [...] >>>>>> >>>>>> >>>>>>> +static const struct iio_chan_spec_ext_info ltr501_ext_info[] = { >>>>>>> + { >>>>>>> + .name = "intr_persist", >>>>>>> + .read = ltr501_read_intr_prst, >>>>>>> + .write = ltr501_write_intr_prst, >>>>>>> + .shared = IIO_SHARED_BY_TYPE, >>>>>>> + }, >>>>>>> + {}, >>>>>>> +}; >>>>>>> + >>>>>> >>>>>> Would be nice to standardize persistence attribute >>>>>> (IIO_CHAN_INFO_PERSISTENCE). >>>>> >>>>> >>>>> If I understand the behavior correctly it causes that the event >>>>> needs to be >>>>> triggered at least n times before the event is reported by the >>>>> chip. In my >>>>> opinion 'persistence' is not a good term for that. I'm not sure >>>>> what a >>>>> better term is but I think it should go more in the direction of >>>>> ratelimit >>>>> or something. >>>> >>>> I've seen this term used for many devices: >>>> >>>> * TSL25911 ambient light sensor [1] >>>> >>>> [ One set of thresholds can be configured to trigger an interrupt >>>> only when >>>> the ambient light exceeds them for a configurable amount of time >>>> (persistence) >>>> ] >>>> >>>> * TAOS TCS34725 ambient light sensor [2] >>>> [ >>>> The interrupt persistence filter allows the user to define the number >>>> of consecutive >>>> out-of-threshold events necessary before generating an interrupt. >>>> ] >>>> >>>> * Avago SAPDS-9950, Sensortek STK3310 >>>> >>>> I think the TSL25911 datasheet best describes this parameter, as the >>>> amount of time >>>> that ambient light should exceed a threshold until an interrupt is >>>> generated. >>> >>> Ok, that makes more sense. I misunderstood the initial description >>> as that >>> the signal would have to go first above the threshold then below the >>> threshold, and this for a number of times. Whereas it needs to >>> exceed the >>> threshold for a certain amount of time before the event is >>> triggered. If >>> it goes below the threshold before the persistence interval no event is >>> triggered and the counter is reset. >> >> Yes, it needs to cross the threshold n number of times before a event is >> generated. > > Wait. It needs to cross the threshold or it needs to stay above the > threshold? Following is the logic for this chip. If ( data > Upper_threshold or data < Lower_threshold) generate_event() > > -- > To unsubscribe from this list: send the line "unsubscribe linux-iio" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- Sathyanarayanan Kuppuswamy Android kernel developer