Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752082AbbEDIVf (ORCPT ); Mon, 4 May 2015 04:21:35 -0400 Received: from mail-wi0-f174.google.com ([209.85.212.174]:33135 "EHLO mail-wi0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751442AbbEDIV3 (ORCPT ); Mon, 4 May 2015 04:21:29 -0400 MIME-Version: 1.0 In-Reply-To: <5546C72E.2040101@linux.intel.com> References: <1430146908-27919-1-git-send-email-octavian.purdila@intel.com> <1430146908-27919-4-git-send-email-octavian.purdila@intel.com> <64714.10.254.87.235.1430149342.squirrel@linux.intel.com> <553EB0B3.5000707@linux.intel.com> <5546C72E.2040101@linux.intel.com> Date: Mon, 4 May 2015 11:21:27 +0300 Message-ID: Subject: Re: [RFC PATCH 3/3] iio: derive the mounting matrix from ACPI _PLD objects From: Octavian Purdila To: sathyanarayanan.kuppuswamy@linux.intel.com Cc: Jonathan Cameron , Lars-Peter Clausen , Peter Meerwald , Robert Moore , Rafael J Wysocki , Len Brown , linux-api@vger.kernel.org, lkml , "linux-iio@vger.kernel.org" , "linux-acpi@vger.kernel.org" , Srinivas Pandruvada Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3131 Lines: 82 On Mon, May 4, 2015 at 4:11 AM, Sathyanarayanan Kuppuswamy wrote: > Hi Octavian, > > On 04/27/2015 07:23 PM, Octavian Purdila wrote: >> >> On Tue, Apr 28, 2015 at 12:57 AM, sathyanarayanan kuppuswamy >> wrote: >>> >>> Hi >>> >>> On 04/27/2015 08:54 AM, Octavian Purdila wrote: >>>> >>>> On Mon, Apr 27, 2015 at 6:42 PM, Kuppuswamy Sathyanarayanan >>>> wrote: >>>>> >>>>> Since Acpi framework already exports this info to user space, Why not >>>>> do >>>>> this derivation in user space code ? Why do we need new ABI, if the >>>>> same >>>>> can be derived from existing one. >>>>> >>>> The ABI was added in the previous patch so that we can present the >>>> sensor orientation information to userspace even in the case of device >>>> tree. >>> >>> If the main reason for implementing a new ABI is to support DT platforms, >>> Why not implement a version of _PLD for device tree ? Don't you think it >>> would be much better than adding a new ABI to export redundant >>> information ? >>> >> IMO the mounting matrix is more consistent with the IIO ABIs. Although >> I have no issue with repicating _PLD for device tree if people agree >> that it is better. > > Since your main issue is, device tree lacking ABI to specify location > information, you should consider fixing it there. Let's wait for others > comment on this. > > If you think mounting matrix provides more information than what is > supported > by _PLD, then we should consider implementing another ABI. AFAIK, that is > not > the case here. > > Adding adding a new ABI to represent the information that can be derived > from existing ABI does not seem to be useful. AFAICS the ACPI _PLD information is not (yet) exported to userspace. This patch: http://marc.info/?t=140795040700003&r=1&w=2 does not seem to be merged upstream. So there is no existing ABI to derive from :) >> >> >>> Also the location information of the device is not just specific to iio >>> drivers. You should consider that we would have similar requirements for >>> devices implemented as input or platform drivers. >> >> The upstream standard for those sensors where the orientation matters >> (accelerometer, gyro, compass) is IIO. >> >> Granted, there are other device types for which the orientation >> information may be useful (e.g. camera). However the actual >> interpretation and action to be taken is different for each subsystem >> (e.g. in the camera case do the correction via V4L2_CID_HFLIP / >> V4L2_CID_VFLIP) so I think it is better to expose it at the subsystem >> level in a way consistent with the subsystem's ABIs. > > I agree that location information is used differently at different > sub systems. But my question is why we need a new ABI ? > > Why not handle it in user space ? > > - -- 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/