From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-ID: <51AC5153.7050506@analog.com> Date: Mon, 3 Jun 2013 10:18:27 +0200 From: Michael Hennerich Reply-To: MIME-Version: 1.0 To: Jonathan Cameron CC: Jonathan Cameron , "linux-iio@vger.kernel.org" , "device-drivers-devel@blackfin.uclinux.org" Subject: Re: [PATCH] iio: frequency: New driver for Analog Devices ADF4350/ADF4351 Wideband Synthesizers References: <1336398556-5360-1-git-send-email-michael.hennerich@analog.com> <4FA932D9.5010006@cam.ac.uk> <4FA93D00.2070906@analog.com> <4FABB647.3090200@kernel.org> <4FACC2B2.9000601@analog.com> In-Reply-To: <4FACC2B2.9000601@analog.com> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed List-ID: On 05/11/2012 09:41 AM, Michael Hennerich wrote: > On 05/10/2012 02:36 PM, Jonathan Cameron wrote: >> On 5/8/2012 4:34 PM, Michael Hennerich wrote: >>> On 05/08/2012 04:51 PM, Jonathan Cameron wrote: >>>> On 5/7/2012 2:49 PM, michael.hennerich@analog.com wrote: >>>>> From: Michael Hennerich >>>>> >>>>> >>>>> + >>>>> +static const struct iio_chan_spec_ext_info adf4350_ext_info[] = { >>>>> + /* Ideally we use IIO_CHAN_INFO_FREQUENCY, but there are >>>>> + * values> 2^32 in order to support the entire frequency range >>>>> + * in Hz. Using scale is a bit ugly. >>>>> + */ >>>> hmm.. Add IIO_VAL_MEGA_PLUS_INT.. We were always going to need a bigger >>>> version at somepoint... >>> Well - we then need an s64, however read|write_raw feature s32 for >>> val and val2. So shall we pass low word in val and high word in val2? >> I was thinking >> val*1e6 + val2 would fit with what we have done elsewhere? Is that >> enough room? > Hi Jonathan, > > IIO_VAL_MEGA_PLUS_INT versus IIO_VAL_LONG_LONG > > It is enough room. But I wonder why we would do costly divide and modulus operations, when we can do sifts and ANDs? Splitting a s64 would give is the maximum available room with very little overhead. > > Thoughts? Hi Jonathan, I like to touch base on the IIO_VAL_MEGA_PLUS_INT versus IIO_VAL_LONG_LONG thing again. We need something bigger as IIO_VAL_INT without loosing granularity by using scale. You're favorite is still IIO_VAL_MEGA_PLUS_INT? I need to implement something - just like to get everyones thought again. -- Greetings, Michael -- Analog Devices GmbH Wilhelm-Wagenfeld-Str. 6 80807 Muenchen Sitz der Gesellschaft: Muenchen; Registergericht: Muenchen HRB 40368; Geschaeftsfuehrer:Dr.Carsten Suckrow, Thomas Wessel, William A. Martin, Margaret Seif