Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751793AbdIJOAp convert rfc822-to-8bit (ORCPT ); Sun, 10 Sep 2017 10:00:45 -0400 Received: from mout02.posteo.de ([185.67.36.66]:59483 "EHLO mout02.posteo.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751739AbdIJOAl (ORCPT ); Sun, 10 Sep 2017 10:00:41 -0400 Date: Sun, 10 Sep 2017 16:00:35 +0200 In-Reply-To: <20170910144424.28e97d1d@archlinux> References: <1503879782-11945-1-git-send-email-harinath922@gmail.com> <1699ec2db96b498478b95a3cbcfe73ca@posteo.de> <20170903172437.0aaec34d@archlinux> <20170910144424.28e97d1d@archlinux> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT Subject: Re: [PATCH v5] iio: accel: mma8452: improvements to handle multiple events To: Jonathan Cameron , harinath Nampally CC: knaack.h@gmx.de, lars@metafoo.de, Peter Meerwald-Stadler , Greg KH , linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, Alison Schofield From: Martin Kepplinger Message-ID: <71459A58-C26C-4956-B8E6-655841F219CB@posteo.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4402 Lines: 135 Am 10. September 2017 15:44:24 MESZ schrieb Jonathan Cameron : >On Mon, 4 Sep 2017 23:06:37 -0400 >harinath Nampally wrote: > >> > I agree with your understanding. It's a rising threshold, just >that the input >> > will only reflect high frequency changes in the signal. >> Thank you for the clarification. I am hoping this gets merged in the >> next window if no other issues. > >There is still the open question to Martin on what he meant in his >review to be addressed. > >Martin, any comments on this? > >I'm really looking for an OK from Martin before I take this one. >Plenty of time though given the merge window is still open! I had a look at v6 of this. > >I'm travelling this week so response may be a bit random depending >on conference wifi and how interesting the material is ;) enjoy, martin > >Jonathan > >> >> Thanks, >> Hari >> >> On Sun, Sep 3, 2017 at 12:24 PM, Jonathan Cameron >wrote: >> > On Tue, 29 Aug 2017 23:01:16 -0400 >> > harinath Nampally wrote: >> > >> >> > We should never say "transient is for rising >> >> > direction" or "ff_mt is for falling direction". any combination >is fine. >> >> >> >> Ok I agree that there is no hard and fast rule that "transient is >for rising >> >> direction" or "ff_mt is for falling direction". >> >> But in our case, datasheet for these chips define these events >based on >> >> acceleration magnitude rising or falling below a set threshold >value. >> >> >> >> For quick reference, below excerpts are from fxls8471 datasheet: >> >> Motion Event: "When the acceleration exceeds a set threshold for a >set >> >> amount of time, >> >> the motion interrupt is asserted." >> >> >> >> Freefall event: "The detection of “Freefall” involves the >monitoring >> >> of the X, Y, and Z axes >> >> for the condition where the acceleration magnitude is below a >> >> user-specified threshold >> >> for a user-definable amount of time" >> >> >> >> Transient event: "When the high-pass filter is bypassed, the >> >> functionality becomes >> >> similar to the motion-detection function; in this mode, >acceleration >> >> greater than >> >> a programmable threshold is detected (along an axis)." >> >> >> >> Therefore I think in this driver freefall event is defined as >> >> 'falling' event type and >> >> motion event is defined as 'rising' event type and Transient is >also defined as >> >> 'rising' event type. >> >> As you might already know that mma8562 and mma8563 doesn't have >> >> transient event support >> >> but they do have freefall and motion event support which are >defined >> >> as 'fall' and 'rise' >> >> event types respectively. Please note in this driver, motion event >is >> >> enabled/configured only >> >> for mma8652 and mma8653. >> >> Therefore if I read/write sysfs node for 'rise' it should use the >> >> FF_MT registers for mma8652 and mma853, but for all others like >> >> mma8451, mma8452 and >> >> mma8453 which has transient event support it picks the Transient >> >> registers if enabled. Also please >> >> note transient event is enabled(but not motion event) for mma8451, >> >> mma8452 and mma8453. >> >> The problem seems like we have two different events(motion and >> >> transient) that are defined >> >> as same event type 'rising' but in fact both motion and transient >are >> >> pretty much similar as they >> >> both raise interrupt flag when the acceleration magnitude rises >above >> >> the threshold. >> >> Only difference is transient event has its own event config >registers >> >> with High pass filter. >> >> If HPF bypassed using config register transient event acts like >motion >> >> detection event. >> > >> >> >> >> That was my understanding but please correct me if I am wrong. >> > >> > I agree with your understanding. It's a rising threshold, just >that the input >> > will only reflect high frequency changes in the signal. >> > >> >> >> >> > Only freefall mode needs one fix: remembering to which set of >registers to fall back when >> >> > disabling it. >> >> >> >> I don't quite understand what you mean by 'to fall back when >disabling >> >> it'. Please elaborate. I would >> >> appreciate if you could suggest your logic in the form of >pseudo-code. >> >> Thanks for your time >> >> >> > ... -- Martin Kepplinger http://martinkepplinger.com sent from mobile