From patchwork Tue Aug 29 19:51:35 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Brown X-Patchwork-Id: 9928201 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 473636022E for ; Tue, 29 Aug 2017 19:51:49 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 38C4028A4A for ; Tue, 29 Aug 2017 19:51:49 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 2D66328A55; Tue, 29 Aug 2017 19:51:49 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_NONE,T_DKIM_INVALID autolearn=no version=3.3.1 Received: from alsa0.perex.cz (alsa0.perex.cz [77.48.224.243]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 1903828A4A for ; Tue, 29 Aug 2017 19:51:47 +0000 (UTC) Received: from alsa0.perex.cz (localhost [127.0.0.1]) by alsa0.perex.cz (Postfix) with ESMTP id A7396266F44; Tue, 29 Aug 2017 21:51:45 +0200 (CEST) X-Original-To: alsa-devel@alsa-project.org Delivered-To: alsa-devel@alsa-project.org Received: by alsa0.perex.cz (Postfix, from userid 1000) id 3987B266F89; Tue, 29 Aug 2017 21:51:44 +0200 (CEST) Received: from heliosphere.sirena.org.uk (heliosphere.sirena.org.uk [172.104.155.198]) by alsa0.perex.cz (Postfix) with ESMTP id 0AD59266E37 for ; Tue, 29 Aug 2017 21:51:41 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sirena.org.uk; s=20170815-heliosphere; h=Date:Message-Id:In-Reply-To: Subject:Cc:To:From:Sender:Reply-To:MIME-Version:Content-Type: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:References: List-Id:List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner: List-Archive; bh=DG0+sgKR+cjCK3jnInZOWvnNmhCJLp66GZupnkrVpiM=; b=cgE4yXFRHfBu iHmuHfjmP49uqWYMhw5sUXouf1tluHL89uy8sDsn6xUiHZ9eMPZjhkkj/K46bwkCoMQTV8p905oJs wqANfQ/Zdhfe5Py5Fb4MqdNyI/+Pmx9EhfB8GQbqvoqCCmPdsLl/0cnt+/YpjH9J4AIPD3SnNXixO 17Tao=; Received: from 92.40.248.112.threembb.co.uk ([92.40.248.112] helo=finisterre.ee.mobilebroadband) by heliosphere.sirena.org.uk with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1dmmXw-00041g-JH; Tue, 29 Aug 2017 19:51:36 +0000 Received: by finisterre.ee.mobilebroadband (Postfix, from userid 1000) id EFFAB4400FC; Tue, 29 Aug 2017 20:51:35 +0100 (BST) From: Mark Brown To: Oskar Schirmer In-Reply-To: <1503697016-21422-1-git-send-email-oskar@scara.com> Message-Id: <20170829195135.EFFAB4400FC@finisterre.ee.mobilebroadband> Date: Tue, 29 Aug 2017 20:51:35 +0100 (BST) Cc: alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org, Takashi Iwai , Liam Girdwood , Peter Ujfalusi , Mark Brown , Dan Murphy , Fabio Estevam , Andrew Morton , Andreas Dannenberg Subject: [alsa-devel] Applied "ASoC: tas2552: Fix fraction overflow in PLL calculation" to the asoc tree X-BeenThere: alsa-devel@alsa-project.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: alsa-devel-bounces@alsa-project.org Sender: alsa-devel-bounces@alsa-project.org X-Virus-Scanned: ClamAV using ClamSMTP The patch ASoC: tas2552: Fix fraction overflow in PLL calculation has been applied to the asoc tree at git://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git All being well this means that it will be integrated into the linux-next tree (usually sometime in the next 24 hours) and sent to Linus during the next merge window (or sooner if it is a bug fix), however if problems are discovered then the patch may be dropped or reverted. You may get further e-mails resulting from automated or manual testing and review of the tree, please engage with people reporting problems and send followup patches addressing any issues that are reported if needed. If any updates are required or you are submitting further changes they should be sent as incremental updates against current git, existing patches will not be replaced. Please add any relevant lists and maintainers to the CCs when replying to this mail. Thanks, Mark From 1bb7cb68feb73a8106546cbd3379590297b0a950 Mon Sep 17 00:00:00 2001 From: Oskar Schirmer Date: Fri, 25 Aug 2017 21:36:56 +0000 Subject: [PATCH] ASoC: tas2552: Fix fraction overflow in PLL calculation Setting the PLL involves the calculation of a fixed point ratio with 4 decimal digits fraction, referred to as "J.D". The fraction "D" is stored separately from the integer part "J" and is limited to 0..9999. The current algorithm uses integer registers to calculate the fraction part, but failed to compensate for rounding errors, resulting in values larger than 9999 for the fraction part occasionally, e.g. for 44.1kHz audio rate and pll_clkin = 3763400 it would set J to 11 and D to 10002, which will at best result in wrong pitch. The critical part is the "pll_clkin / 10000", which would be ok with real numbers, but using integer arithmetic the rounding decreases the divisor, thus increasing the final quotient. The issue is solved by linear interpolation over the reciprocal function between the two adjacent points with integer divisor, i.e. pll_clkin / 10000 and pll_clkin / 10000 + 1, and doing all rounding to the lower result. As a side effect to the bug fix, the approximation to the desired frequency is much better, for the above mentioned example we get 11.9993, while the true ratio is 11.9993623. Signed-off-by: Oskar Schirmer Signed-off-by: Mark Brown --- sound/soc/codecs/tas2552.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/sound/soc/codecs/tas2552.c b/sound/soc/codecs/tas2552.c index 8840f72f3c4a..10116169a239 100644 --- a/sound/soc/codecs/tas2552.c +++ b/sound/soc/codecs/tas2552.c @@ -192,7 +192,7 @@ static int tas2552_setup_pll(struct snd_soc_codec *codec, * pll_clk = (.5 * pll_clkin * J.D) / 2^p * Need to fill in J and D here based on incoming freq */ - unsigned int d; + unsigned int d, q, t; u8 j; u8 pll_sel = (tas2552->pll_clk_id << 3) & TAS2552_PLL_SRC_MASK; u8 p = snd_soc_read(codec, TAS2552_PLL_CTRL_1); @@ -200,9 +200,12 @@ static int tas2552_setup_pll(struct snd_soc_codec *codec, p = (p >> 7); recalc: - j = (pll_clk * 2 * (1 << p)) / pll_clkin; - d = (pll_clk * 2 * (1 << p)) % pll_clkin; - d /= (pll_clkin / 10000); + t = (pll_clk * 2) << p; + j = t / pll_clkin; + d = t % pll_clkin; + t = pll_clkin / 10000; + q = d / (t + 1); + d = q + ((9999 - pll_clkin % 10000) * (d / t - q)) / 10000; if (d && (pll_clkin < 512000 || pll_clkin > 9200000)) { if (tas2552->pll_clk_id == TAS2552_PLL_CLKIN_BCLK) {