Received: by 2002:a05:7412:5112:b0:fa:6e18:a558 with SMTP id fm18csp1795183rdb; Thu, 25 Jan 2024 06:27:27 -0800 (PST) X-Google-Smtp-Source: AGHT+IF+2uxD9rO59eOoJFhnKhix63TNS6RpgoaMIPPSEwvq3bcIuR8AHl2SWvBbYtKvycTqiZLJ X-Received: by 2002:a17:902:7444:b0:1d7:2509:4d79 with SMTP id e4-20020a170902744400b001d725094d79mr972354plt.79.1706192846974; Thu, 25 Jan 2024 06:27:26 -0800 (PST) ARC-Seal: i=2; a=rsa-sha256; t=1706192846; cv=pass; d=google.com; s=arc-20160816; b=wYMbuZjEHuoh9Xo32m7Ub3C9AWAX2pRfQWxGFkL5S05hemKvg2hzvwKL94hJ+qNjcG SkYUoj8eJPpQPya/PiK/j94q+guI9HFX55yLeMT2KfQOCH0vKk6S83nJ//1fEqmUxHYx l7Z5q/j0yTWFNB5FJN636D3hdXYgkHxjVvR8sgGByvTkDmxIi5UlVM94MQ7s66FvM1VF e5cNqTzgAUCoTZ/I9BVXFfySYjpJm7/5l4OY4l81vcDYITnWhqmvbSyo6RAxLMbZ9/f0 6kkxP8DRNh/lwVKj3oDCXrTM5BVfDwSRx8kx15iSHmZWJDdUAgW0Lj6tA1sFFriygmK+ P55Q== ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-disposition:mime-version:list-unsubscribe:list-subscribe :list-id:precedence:message-id:subject:cc:to:from:date :dkim-signature; bh=7uD8uO6W0P3VobMqY6RhL29xNcpRHCUEHzBOg3bakiE=; fh=wSGMR59YoE2MTNFuv5+gaOzLrfsgA3SX0uiggGzInvY=; b=qrXT3NncmSqyuWR+Hgk6aXnrLvgk3Wx7qiqS/GAi6Ho2GjfPAQwi35jy/Ozwl0ZP6x Wu5m8x+LJGUM3bAB5vWNXkv8czvUV3/PG95YZWvR3d9d/E8OLmz/ZXZ2bpIqO7+ysRJZ DMjs2uBmcBwcxePfziWlrWjYPgXEDrSYd1hrwuvrPeS3be9czZUNpuXx3SEiqWqh0Abu D2qDk3SC170hXY3gKTCBTzfKoQX0DBaLTPuyc1SLzM26ipmBaXv/4Qjdcic6V2QKRPek BnlhFEVNyB751oBQcD02i7dQ3uL9CmlK0tSxmV6vsjFtIETdE8qkTe++FR/ABE8cv4bt 3Kww== ARC-Authentication-Results: i=2; mx.google.com; dkim=pass header.i=@gmail.com header.s=20230601 header.b=C7L0bqtm; arc=pass (i=1 spf=pass spfdomain=gmail.com dkim=pass dkdomain=gmail.com dmarc=pass fromdomain=gmail.com); spf=pass (google.com: domain of linux-kernel+bounces-38721-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45e3:2400::1 as permitted sender) smtp.mailfrom="linux-kernel+bounces-38721-linux.lists.archive=gmail.com@vger.kernel.org"; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Return-Path: Received: from sv.mirrors.kernel.org (sv.mirrors.kernel.org. [2604:1380:45e3:2400::1]) by mx.google.com with ESMTPS id j15-20020a170903024f00b001d0b6ba6109si13617788plh.248.2024.01.25.06.27.26 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 25 Jan 2024 06:27:26 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel+bounces-38721-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45e3:2400::1 as permitted sender) client-ip=2604:1380:45e3:2400::1; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20230601 header.b=C7L0bqtm; arc=pass (i=1 spf=pass spfdomain=gmail.com dkim=pass dkdomain=gmail.com dmarc=pass fromdomain=gmail.com); spf=pass (google.com: domain of linux-kernel+bounces-38721-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45e3:2400::1 as permitted sender) smtp.mailfrom="linux-kernel+bounces-38721-linux.lists.archive=gmail.com@vger.kernel.org"; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Received: from smtp.subspace.kernel.org (wormhole.subspace.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sv.mirrors.kernel.org (Postfix) with ESMTPS id 5B7C828D26E for ; Thu, 25 Jan 2024 14:27:04 +0000 (UTC) Received: from localhost.localdomain (localhost.localdomain [127.0.0.1]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 24AE06341F; Thu, 25 Jan 2024 14:26:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="C7L0bqtm" Received: from mail-lf1-f53.google.com (mail-lf1-f53.google.com [209.85.167.53]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9D20763500; Thu, 25 Jan 2024 14:26:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.167.53 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706192812; cv=none; b=SUo0qWXK/h1BcR0KCN5Nnk8HyH+Mmy4S1wfMAEAYcwcOrQkuv4pAAwLiVIULawSB5S+kNlqjouVZzmxQeXB9K2agVpJjf3YQOxOa+mzX+QH63Eqx+sex84SWvM/ZXVGfjqDTxO0LoJSftC3GEMgwfV2ZtRe4LDQgOCks0Vzdjy8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706192812; c=relaxed/simple; bh=RWLKO/AtH0Uj+yL0MoMxKrixm64mWC7/e4QlFC0ewLg=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition; b=Vz0IgPqhlqfkV7eWmdQ7dr61hcpF3/9f+jj+fUMCZH6D8UTDexqUaLenGFSrwfpTrRNMAiiumMcqhWV87dZ+/WfeW0b/IYBiHQ06zlGB/ZxXVM6rBSXQx5geA5Q0eJC3pc+Moiuc0bHUzttlpTSt2tHbUzu+9irhFyxH6dwFB7Y= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=C7L0bqtm; arc=none smtp.client-ip=209.85.167.53 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Received: by mail-lf1-f53.google.com with SMTP id 2adb3069b0e04-5102188d2aeso299658e87.2; Thu, 25 Jan 2024 06:26:50 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1706192808; x=1706797608; darn=vger.kernel.org; h=content-disposition:mime-version:message-id:subject:cc:to:from:date :from:to:cc:subject:date:message-id:reply-to; bh=7uD8uO6W0P3VobMqY6RhL29xNcpRHCUEHzBOg3bakiE=; b=C7L0bqtmV3d+mhWj7mIFM5sgLs7tG8VOvbFyZJRmxV1e6hPSMQrufn8UdMJ4Wta2+v 8wJj+M9xayTOPPJU9rXKeZQuoJKpX1EQvrYWdHtavpRsrDUKdYgq9uhgctqPHjed3eE9 11a9TtH/frOOasN2ZLZ1+mWrmUyUT7I1p32clSdgdpv+lPGSDA9F8m/dAV/XUP8+pSV4 o3e1avGPSqmbEBGYBFlsnHdcob8OMxef86Fnek/DrZbXI/wdhHCnPur4vQXTrX9S8wzi USN2xIZ8nXW0LNg6oM79T9jk2QdHAnDTT6l5NoH3AaN5p5VnNCjh9WdKJetpLD/inaZ1 uuNg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1706192808; x=1706797608; h=content-disposition:mime-version:message-id:subject:cc:to:from:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=7uD8uO6W0P3VobMqY6RhL29xNcpRHCUEHzBOg3bakiE=; b=r2zPA2KNSaT59VcBIEL/ArFNm/+2xVS4QkdgLTMVcKD0RTul4KTDQOWfiHS/QoMuOp 1QF+WBLIWkM+UX9qmbKdlpzQ3ZAoGScIfpychklaZMZzrpDVqBXAar4Phubx8P3OxhzS O1cvHBeMZChGexEk7zqCIRgPM7TMyX5TSkXpmYMXWfduYgYnK+e1C5h1Fvj/iF0KDfzl aCF6sIbilbd4IiWOeMnQVH4GSe9Wx02r4IJenkcJtmNwIo0ELhFXff7aN+dff0TvR59O Xxz/I/7wOa9m2LBjbbKvopyfsElXQwxb63727plF6KXMaHlc0X1e3C8CatDNKho49F9G J0Cg== X-Gm-Message-State: AOJu0YzPId2B3TBGvYEpcFNV4pCw4U6TT38PDsWB0fIUAZnw+yKnLbrA ++BNOLwMmohOiAv7bJfM/O7ZaDebD61C45C4OvciBVf9d0h0FUsw X-Received: by 2002:ac2:5202:0:b0:50e:7555:1eb2 with SMTP id a2-20020ac25202000000b0050e75551eb2mr572160lfl.74.1706192808293; Thu, 25 Jan 2024 06:26:48 -0800 (PST) Received: from drtxq0yyyyyyyyyyyyybt-3.rev.dnainternet.fi (drtxq0yyyyyyyyyyyyybt-3.rev.dnainternet.fi. [2001:14ba:7426:df00::3]) by smtp.gmail.com with ESMTPSA id o1-20020ac24c41000000b0050ea7b615c3sm2871101lfk.230.2024.01.25.06.26.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 25 Jan 2024 06:26:47 -0800 (PST) Date: Thu, 25 Jan 2024 16:26:40 +0200 From: Matti Vaittinen To: Matti Vaittinen , Matti Vaittinen Cc: Jonathan Cameron , Lars-Peter Clausen , Matti Vaittinen , linux-kernel@vger.kernel.org, David Laight , Subhajit Ghosh , linux-iio@vger.kernel.org Subject: [PATCH v2] iio: gts-helper: Fix division loop Message-ID: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="58OujoI1kgFawucR" Content-Disposition: inline --58OujoI1kgFawucR Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable The loop based 64bit division may run for a long time when dividend is a lot bigger than the divider. Replace the division loop by the div64_u64() which implementation may be significantly faster. Signed-off-by: Matti Vaittinen Fixes: 38416c28e168 ("iio: light: Add gain-time-scale helpers") --- This change was earlier applied and reverted as it confusingly lacked of the removal of the overflow check (which is only needed when we do looping "while (full > scale * (u64)tmp)". As this loop got removed, the check got also obsolete and leaving it to the code caused some confusion. So, I marked this as a v2, where v1 is the reverted change discussed here: https://lore.kernel.org/linux-iio/ZZZ7pJBGkTdFFqiY@dc78bmyyyyyyyyyyyyydt-3.= rev.dnainternet.fi/ Revision history: v1 =3D> v2: - Drop the obsolete overflow check - Rebased on top of the v6.8-rc1 iio: gts: loop fix fix --- drivers/iio/industrialio-gts-helper.c | 15 +-------------- 1 file changed, 1 insertion(+), 14 deletions(-) diff --git a/drivers/iio/industrialio-gts-helper.c b/drivers/iio/industrial= io-gts-helper.c index 7653261d2dc2..b51eb6cb766f 100644 --- a/drivers/iio/industrialio-gts-helper.c +++ b/drivers/iio/industrialio-gts-helper.c @@ -34,24 +34,11 @@ static int iio_gts_get_gain(const u64 max, const u64 scale) { u64 full =3D max; - int tmp =3D 1; =20 if (scale > full || !scale) return -EINVAL; =20 - if (U64_MAX - full < scale) { - /* Risk of overflow */ - if (full - scale < scale) - return 1; - - full -=3D scale; - tmp++; - } - - while (full > scale * (u64)tmp) - tmp++; - - return tmp; + return div64_u64(full, scale); } =20 /** base-commit: 6613476e225e090cc9aad49be7fa504e290dd33d --=20 2.43.0 --=20 Matti Vaittinen, Linux device drivers ROHM Semiconductors, Finland SWDC Kiviharjunlenkki 1E 90220 OULU FINLAND ~~~ "I don't think so," said Rene Descartes. Just then he vanished ~~~ Simon says - in Latin please. ~~~ "non cogito me" dixit Rene Descarte, deinde evanescavit ~~~ Thanks to Simon Glass for the translation =3D]=20 --58OujoI1kgFawucR Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEIx+f8wZb28fLKEhTeFA3/03aocUFAmWyb5sACgkQeFA3/03a ocVdBQf6AmGWHNraNeG7q7msDYkGPGvzuKfJ0PUE8JDxvkfGj+7kjCBWLxTGZ0xP RuRiI6Rdus7H6qfmwOLVmzW+jGuWoTtpHU7xi4fkESyEwwUZVAzM/3p0EurevOIM wgbHQIZLkvtQY8uYNXy5bb7QZV2MYFwFUssdHSM+iYM7kWLt8e7xR4X3ZIoQy8cn 8sTzxzz3cQG2ATlUJbFPL15Wsemt51p7C4To0x5UVRtsGNQk/av9jiKy8Rgad0Mf 5yaPvw1UgcADcsA5XuQRu5nX77NZlMPIzySlQ4p62Jvstwu64qpylKzKo25eMGp6 03tEDDohL190qLsnw0KM5q540VYLEA== =0E+9 -----END PGP SIGNATURE----- --58OujoI1kgFawucR--