Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755527AbaKEPcP (ORCPT ); Wed, 5 Nov 2014 10:32:15 -0500 Received: from saturn.retrosnub.co.uk ([178.18.118.26]:43374 "EHLO saturn.retrosnub.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754822AbaKEPcN (ORCPT ); Wed, 5 Nov 2014 10:32:13 -0500 Message-ID: <545A42FA.7090501@kernel.org> Date: Wed, 05 Nov 2014 15:32:10 +0000 From: Jonathan Cameron User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 MIME-Version: 1.0 To: "Ivan T. Ivanov" CC: Hartmut Knaack , Lars-Peter Clausen , Peter Meerwald , Stanimir Varbanov , Angelo Compagnucci , Grant Likely , linux-kernel@vger.kernel.org, linux-iio@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-msm@vger.kernel.org Subject: Re: [PATCH v4 2/2] iio: vadc: Qualcomm SPMI PMIC voltage ADC driver References: <1415028270-25860-1-git-send-email-iivanov@mm-sol.com> <1415028270-25860-3-git-send-email-iivanov@mm-sol.com> <545A218F.5060301@kernel.org> <1415195855.3660.4.camel@mm-sol.com> <545A2EDB.5040801@kernel.org> <1415199681.3660.8.camel@mm-sol.com> In-Reply-To: <1415199681.3660.8.camel@mm-sol.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/11/14 15:01, Ivan T. Ivanov wrote: > > On Wed, 2014-11-05 at 14:06 +0000, Jonathan Cameron wrote: >> On 05/11/14 13:57, Ivan T. Ivanov wrote: >>> On Wed, 2014-11-05 at 13:09 +0000, Jonathan Cameron wrote: >>>> On 03/11/14 15:24, Ivan T. Ivanov wrote: >>>>> From: Stanimir Varbanov >>>>> >>>>> The voltage ADC is peripheral of Qualcomm SPMI PMIC chips. It has >>>>> 15 bits resolution and register space inside PMIC accessible across >>>>> SPMI bus. >>>>> >>>>> The vadc driver registers itself through IIO interface. >>>>> >>>>> Signed-off-by: Stanimir Varbanov >>>>> Signed-off-by: Ivan T. Ivanov >>>> Hi Ivan, >>>> >>>> Couple of utterly tiny bits inline. The biggest one is that >>>> you store some info about the calibration that you never actually >>>> use... Left over from some debugging perhaps? >>>> >>>> Jonathan >>> >>> >>> >>>>> + >>>>> +/* >>>>> + * VADC_CALIB_ABSOLUTE: uses the 625mV and 1.25V as reference channels. >>>>> + * VADC_CALIB_RATIOMETRIC: uses the reference voltage (1.8V) and GND for >>>>> + * calibration. >>>>> + */ >>>>> +enum vadc_calibration { >>>>> + VADC_CALIB_ABSOLUTE = 0, >>>>> + VADC_CALIB_RATIOMETRIC >>>>> +}; >>>>> + >>>>> +/** >>>>> + * struct vadc_linear_graph - Represent ADC characteristics. >>>>> + * @dy: numerator slope to calculate the gain. >>>> As dy is always equal to vref-gnd you could drop it and use those >>>> directly... >>>> >>>> Conversly you store vref or grnd and never use them... >>> >>> I am not sure I am following you. Please take a look in >>> vadc_measure_ref_points() and vadc_calibrate(). >> Good point on grnd, but vref is set but never read anywhere that I can find.. >> > > Right. At this point it is not used. Driver right now provide basic per > channel voltage measurements. The plan is to add temperature compensation for the > measurements and additional scaling functions which are specific per channel. > > I could drop this field from initial driver version if you like. Probably best as otherwise some compiler in a clever mood will give a warning and I'll get an irritating patch to remove it! J > > Regards, > Ivan > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/