From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_2 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0C272C7618B for ; Sun, 28 Jul 2019 08:34:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D2D8B214C6 for ; Sun, 28 Jul 2019 08:34:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564302860; bh=MbqHmXO5YZd8uWQm+FlJEdearXUQPKipfL5ob5AhD0c=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=08PT8sBMNrPEop4yTvsyAkJ2AFg9+DDq+qme0gNcw+mRr9hDHTDcfBV5cmE7Kj0k2 RdFSRYqNjHuq28mUOGiHRijylc7ufYtgC/aJkHxbNgSEOLG/B6k9s3BG8gjY61Y5+V BMrLRsu5+jPG6NTj715SDj7eTWU7HKnwv10Cobfo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726010AbfG1IeU (ORCPT ); Sun, 28 Jul 2019 04:34:20 -0400 Received: from mail.kernel.org ([198.145.29.99]:58066 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725880AbfG1IeU (ORCPT ); Sun, 28 Jul 2019 04:34:20 -0400 Received: from archlinux (cpc149474-cmbg20-2-0-cust94.5-4.cable.virginm.net [82.4.196.95]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5B3462085A; Sun, 28 Jul 2019 08:34:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564302858; bh=MbqHmXO5YZd8uWQm+FlJEdearXUQPKipfL5ob5AhD0c=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=UVprk842MaZ9gG3VyxDNa4nsWau/ZfI+QDa5L30JlH90ZABceUMQXpQwd8zoCM6ZO E42jUnOE+8VM6i1xPKPjQlhV/EgKR/qvnWx49RMwUENcSM5hHfb6aGneh3kQGvXuOd g+J0nLaO/onIpmCdt2AudcNQdvhg5wa41Wl4aLZg= Date: Sun, 28 Jul 2019 09:34:14 +0100 From: Jonathan Cameron To: Martin Kepplinger Cc: lorenzo.bianconi83@gmail.com, knaack.h@gmx.de, lars@metafoo.de, pmeerw@pmeerw.net, linux-iio@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 4/5] iio: imu: st_lsm6dsx: add support for accel/gyro unit of lsm9sd1 Message-ID: <20190728093414.5d3ca94d@archlinux> In-Reply-To: References: <20190725053132.9589-1-martin.kepplinger@puri.sm> <20190725053132.9589-5-martin.kepplinger@puri.sm> <20190727184844.307255a2@archlinux> X-Mailer: Claws Mail 3.17.4 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-iio-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org On Sun, 28 Jul 2019 08:04:51 +0200 Martin Kepplinger wrote: > On 27.07.19 19:48, Jonathan Cameron wrote: > > On Thu, 25 Jul 2019 07:31:31 +0200 > > Martin Kepplinger wrote: > > > >> The LSM9DS1's accelerometer / gyroscope unit and it's magnetometer (separately > >> supported in iio/magnetometer/st_magn*) are located on a separate i2c addresses > >> on the bus. > >> > >> For the datasheet, see https://www.st.com/resource/en/datasheet/lsm9ds1.pdf > >> > >> Treat it just like the LSM6* devices and, despite it's name, hook it up > >> to the st_lsm6dsx driver, using it's basic functionality. > >> > >> Signed-off-by: Martin Kepplinger > > I'm a little confused on this hardware. > > > > How does buffered output work if these are independently clocked? > > > > I took a quick look at the datasheet, and 'suspect' the answer is that > > it runs at the gyro frequencies if both are enable. Is that right? > > > > Thanks for reviewing, Jonathan, > > Correct. It says so in chapter 7.12. But that's a "problem" with all > these imu devices, not specific to this addition right? It's not a problem as such, but there is a related difference in this device to the others supported by this driver. The other parts seem to allow for independent data rate setting, with streaming to the buffer that isn't in 'lock step'. I.e you can get Ax_1, Ay_1, Az_1, Gx_1, Gy_1, Gz_1, Gx_2, Gy_2, Gz_2, Ax_2, Ay_2, Az_2, Gy_3... That required us to split them up into two devices and means that, to fuse data from these two source, userspace has to do the harder job of aligning the two datasets. For this device, things are simpler in that you always a 'scan' that goes across both accelerometer and gyroscope channels. That allows us to represent it as a single IIO device with a single buffer. I'm not seeing any reference in the lsm9ds1 to the pattern registers that are used to handle difference in frequency for the other parts by letting us know what is actually present in each data set in the fifo. Now, that doesn't meant we can't still handle them separately given we already do that for other parts. Anyhow, is my understanding correct? Jonathan > > Sidenote: I thought about renaming things to "lsm6ds0" here just because > of the name and because the registers are (almost) the same as for my > lsm9ds1. But I'm not a fan of blindly doing that without being able to > test. When the current patchset looks good to you, let's keep it that way. > > martin