From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.16]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DBE8131E854; Wed, 4 Mar 2026 11:51:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.16 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772625139; cv=none; b=P2RmTokMf3a44nqst/IVjGiG8PrptbCgShKtE78Ar9CcY0dD0EAMeMT5AZeYDHyPGZFVey8Ezh6Cpcp3bbGgeEonmPtQtVOMRv9+vNQNZl+MPYdsoEJ9k8gYjNVU77t4g/oPAe0VSKJzTvh62Gtzy3LJzjdry3IRhz92l2WPCFM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772625139; c=relaxed/simple; bh=1cbNHjS3Jwr1X06Tb+6bXSS1cl+vAw/B+P8pT+WbDeE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=NLyW/fWSHIQscMA81eF1BATjhQs23I6+9euvdbZ93VleuqIEx9vV9wGqpR8qTXGlpRK/G5LmpVJDGwScBhLuIj8MsfKsEKD/BG1J9u/7YHfvrAAVBe/zPsAy8bsLdxXCpEa2qbjDEpr/KXwTfs8bY5NbygcN5yOElDB1cVna2ik= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=bhTZBllA; arc=none smtp.client-ip=192.198.163.16 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="bhTZBllA" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1772625120; x=1804161120; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=1cbNHjS3Jwr1X06Tb+6bXSS1cl+vAw/B+P8pT+WbDeE=; b=bhTZBllAanQ9KH2CiT23/nxt1E29N1jMrRApm2kS+jRmWg5r6WfQV7+Q 8kV+H7UEBMUjnAVxlRGM4wSXo2N10gARy10mVVDrfx4jCiWXMXYbQa+E3 74wiF5abgp2YbHSan8d0Ca8cqZ47ykW3IM8WwQX+0eK6Q/6A7JdTDEV7y 1pCIvT0o/WvsiMJmaiBRVpExQ69iKGwAwqmZFsDH2HAD0VwVqyniLA1Hf IKH3GYvz1+SD63+yIRwKQdZmJJ0p5WlclwDsCI9Hvvu/s3DYGCtzDUK0e XCw5kefOaKrcEMO5v975Nm72QctKNSKbK3/r6zvfvn1CBNG3xlTrxOrpw A==; X-CSE-ConnectionGUID: NdzJmUfYTB6d+gorbSb2Cg== X-CSE-MsgGUID: tdrYEFTgQx6xBmspYhKFYA== X-IronPort-AV: E=McAfee;i="6800,10657,11718"; a="61257210" X-IronPort-AV: E=Sophos;i="6.21,323,1763452800"; d="scan'208";a="61257210" Received: from orviesa007.jf.intel.com ([10.64.159.147]) by fmvoesa110.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Mar 2026 03:51:56 -0800 X-CSE-ConnectionGUID: eDtDSgfsQbi4u9QQ+mFcRw== X-CSE-MsgGUID: Iss5/j+2Sku/SvffDzin0g== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.21,323,1763452800"; d="scan'208";a="218431822" Received: from abityuts-desk.ger.corp.intel.com (HELO localhost) ([10.245.245.127]) by orviesa007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Mar 2026 03:51:54 -0800 Date: Wed, 4 Mar 2026 13:51:51 +0200 From: Andy Shevchenko To: Francesco Lavra Cc: Jonathan Cameron , David Lechner , Nuno =?iso-8859-1?Q?S=E1?= , Andy Shevchenko , linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v7 5/6] iio: ABI: Add partial quaternion modifier Message-ID: References: <20260304080519.2844101-1-flavra@baylibre.com> <20260304080706.2844472-1-flavra@baylibre.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260304080706.2844472-1-flavra@baylibre.com> Organization: Intel Finland Oy - BIC 0357606-4 - c/o Alberga Business Park, 6 krs, Bertel Jungin Aukio 5, 02600 Espoo On Wed, Mar 04, 2026 at 09:07:05AM +0100, Francesco Lavra wrote: > This modifier applies to the IIO_ROT channel type, and indicates a data > representation that specifies the {x, y, z} components of the normalized > quaternion vector. ... > +What: /sys/bus/iio/devices/iio:deviceX/in_rot_partial_quaternion_raw > + Raw value of {x, y, z} components of the quaternion vector. These > + components represent the axis about which a rotation occurs, and are > + subject to the following costraints: > + - the quaternion vector is normalized, i.e. x^2 + y^2 + z^2 + w^2 = 1 > + - the rotation angle is within the [-180, 180] range, i.e. the w > + component (which represents the amount of rotation) is non-negative > + These constraints allow the w value to be calculated from the other > + components: w = sqrt(1 - (x^2 + y^2 + z^2)). Just to double check if we really do not have a special mathematical term for that already. If we do, I prefer to have that over odd "partial quaternion". -- With Best Regards, Andy Shevchenko