From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-ID: <4E311F78.6080008@analog.com> Date: Thu, 28 Jul 2011 10:36:08 +0200 From: Michael Hennerich Reply-To: MIME-Version: 1.0 To: Jonathan Cameron CC: "linux-iio@vger.kernel.org" , "device-drivers-devel@blackfin.uclinux.org" Subject: Re: [PATCH 0/2] blue part 6: IIO abi rework References: <1311600234-16128-1-git-send-email-jic23@cam.ac.uk> <544AC56F16B56944AEC3BD4E3D59177143001196A7@LIMKCMBX1.ad.analog.com> <4E2E863C.2010706@cam.ac.uk> <4E2E9C77.9050506@analog.com> <4E2E9FC5.4030809@cam.ac.uk> <4E3023A3.80604@analog.com> <4E3117DD.9060904@cam.ac.uk> <544AC56F16B56944AEC3BD4E3D5917714300119DD5@LIMKCMBX1.ad.analog.com> <4E311FA7.2000200@cam.ac.uk> In-Reply-To: <4E311FA7.2000200@cam.ac.uk> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed List-ID: On 07/28/2011 10:36 AM, Jonathan Cameron wrote: > On 07/28/11 09:08, Hennerich, Michael wrote: >> Jonathan Cameron wrote on 2011-07-28: >>> On 07/27/11 15:41, Michael Hennerich wrote: >>>> On 07/26/2011 01:06 PM, Jonathan Cameron wrote: >>>>> On 07/26/11 11:52, Michael Hennerich wrote: >>>>>> On 07/26/2011 11:17 AM, Jonathan Cameron wrote: >>>>>>> On 07/26/11 10:01, Hennerich, Michael wrote: >>>>>>>> Jonathan Cameron wrote on 2011-07-25: >>>>>>>>> Michael pointed out the issues that not having an explicit >>>>>>>>> direction for channels was causing and the inconsistency of the >>>>>>>>> inX and outX channel naming we got from hmwon. >>>>>>>>> >>>>>>>>> They are stuck with it, but we aren't, so lets fix this now. >>>>>>>>> >>>>>>>>> Interesting question is whether we reset the base units to be >>>>>>>>> volts whilst we are at it? (for voltage channels obviously!) >>>>>>>> What do you mean exactly volts versus milli volts? >>>>>>> Make the in_voltage_scale correspond to conversion to volts instead >>>>>>> of millivolts as now (I think). Err. Looking at it that isn't >>>>>>> actually documented... oops. I wonder which drivers actually do >>>>>>> that and which don't. >>>>>> The ones I wrote provide the scale for millivolts. >>>>>> With the recent introduction of IIO_VAL_INT_PLUS_NANO we got the >>>>>> scale accurate enough for the precession 24-bit converters. >>>>>> If we move to the SI base unit volt, we lose this accuracy again. >>>>> Yup, that's the principal counter argument to the change. >>>> If we decide to leave the milli scale for volts... Do we also want to >>>> stay with milli degrees Celsius, etc.? If we do it for one, probably >>>> best to do it for them all.. >> Hi Jonathan, >> >> So stick with the milli scale for all? > Yes. >>>> One other thing we should also address is the >>>> byte-ordering/endianess of the scan elements stored in the ring buffers. >>>> >>>> Right now the scan_element type details signs, bits, storage bits and >>>> shifts. However it lacks to tell the endianess within the storage bits. >>>> Good point. I'd completely forgotten about that. >>>> >>>> How about le:s16/32>>0 or be:s16/32>>0 for example? >>> Yup, that works for me. In cases where it doesn't matter they driver >>> can pick one at random. >> >> We need another case - Some drivers use the (be|le)(x)_to_cpu() helpers, >> So in case these are used the endianess can be either or, depending on the host. >> So maybe have le|be|cpu? > I thought about that, but am inclined to say we just stop drivers doing the conversion. > Better to leave it up to userspace? Well - we have and definitely will have more drivers where the conversion may be to time consuming to do in kernel space. I really don't have a strong preference here - but the important thing is that we need to tell user space what format is placed into the buffers. >> >> 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 >> >> >> > -- 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