From patchwork Wed Jan 14 11:52:49 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Rosin X-Patchwork-Id: 5630511 Return-Path: X-Original-To: patchwork-alsa-devel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id DCFFF9F357 for ; Wed, 14 Jan 2015 11:57:25 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 2093F20389 for ; Wed, 14 Jan 2015 11:57:24 +0000 (UTC) Received: from alsa0.perex.cz (alsa0.perex.cz [77.48.224.243]) by mail.kernel.org (Postfix) with ESMTP id ABE1F2039D for ; Wed, 14 Jan 2015 11:57:22 +0000 (UTC) Received: by alsa0.perex.cz (Postfix, from userid 1000) id C44042652C2; Wed, 14 Jan 2015 12:57:21 +0100 (CET) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,NO_DNS_FOR_FROM, UNPARSEABLE_RELAY autolearn=no version=3.3.1 Received: from alsa0.perex.cz (localhost [IPv6:::1]) by alsa0.perex.cz (Postfix) with ESMTP id 193B32650AF; Wed, 14 Jan 2015 12:55:02 +0100 (CET) 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 E7F37265192; Wed, 14 Jan 2015 12:54:59 +0100 (CET) Received: from mail.lysator.liu.se (mail.lysator.liu.se [130.236.254.3]) by alsa0.perex.cz (Postfix) with ESMTP id F28172650D8 for ; Wed, 14 Jan 2015 12:53:52 +0100 (CET) Received: from mail.lysator.liu.se (localhost [127.0.0.1]) by mail.lysator.liu.se (Postfix) with ESMTP id 99F6F4000E; Wed, 14 Jan 2015 12:53:52 +0100 (CET) Received: from localhost.localdomain (217-210-101-82-no95.business.telia.com [217.210.101.82]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.lysator.liu.se (Postfix) with ESMTPSA id 0A47C40007; Wed, 14 Jan 2015 12:53:51 +0100 (CET) From: Peter Rosin To: alsa-devel@alsa-project.org Date: Wed, 14 Jan 2015 12:52:49 +0100 Message-Id: <1421236370-19826-7-git-send-email-peda@lysator.liu.se> X-Mailer: git-send-email 1.7.10.4 In-Reply-To: <1421236370-19826-1-git-send-email-peda@lysator.liu.se> References: <1421236370-19826-1-git-send-email-peda@lysator.liu.se> X-Virus-Scanned: ClamAV using ClamSMTP Cc: Mark Brown , Takashi Iwai , Liam Girdwood , linux-kernel@vger.kernel.org, Peter Rosin Subject: [alsa-devel] [PATCH 6/7] ASoC: pcm512x: Avoid the PLL for the DAC clock, if possible 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 From: Peter Rosin The PLL introduces jitter, which in turn introduces noice if used to clock the DAC. Thus, avoid the PLL output, and use the PLL input to drive the DAC clock, if possible. This is described for the PCM5142/PCM5242 chips in the answers to the forum post "PCM5142/PCM5242 DAC clock source" at the TI E2E community pages (1). (1) http://e2e.ti.com/support/data_converters/audio_converters/f/64/t/389994 Signed-off-by: Peter Rosin --- sound/soc/codecs/pcm512x.c | 119 ++++++++++++++++++++++++++++++++++---------- sound/soc/codecs/pcm512x.h | 4 +- 2 files changed, 96 insertions(+), 27 deletions(-) diff --git a/sound/soc/codecs/pcm512x.c b/sound/soc/codecs/pcm512x.c index df8948b4e848..2a50c58a2fb1 100644 --- a/sound/soc/codecs/pcm512x.c +++ b/sound/soc/codecs/pcm512x.c @@ -105,6 +105,7 @@ static const struct reg_default pcm512x_reg_defaults[] = { { PCM512x_VCOM_CTRL_2, 0x01 }, { PCM512x_BCLK_LRCLK_CFG, 0x00 }, { PCM512x_MASTER_MODE, 0x7c }, + { PCM512x_GPIO_DACIN, 0x00 }, { PCM512x_GPIO_PLLIN, 0x00 }, { PCM512x_SYNCHRONIZE, 0x10 }, { PCM512x_PLL_COEFF_0, 0x00 }, @@ -138,6 +139,7 @@ static bool pcm512x_readable(struct device *dev, unsigned int reg) case PCM512x_MASTER_MODE: case PCM512x_PLL_REF: case PCM512x_DAC_REF: + case PCM512x_GPIO_DACIN: case PCM512x_GPIO_PLLIN: case PCM512x_SYNCHRONIZE: case PCM512x_PLL_COEFF_0: @@ -681,6 +683,37 @@ done: return 0; } +static unsigned long pcm512x_pllin_dac_rate(struct snd_soc_dai *dai, + unsigned long osr_rate, + unsigned long pllin_rate) +{ + struct snd_soc_codec *codec = dai->codec; + struct pcm512x_priv *pcm512x = snd_soc_codec_get_drvdata(codec); + unsigned long dac_rate; + + if (!pcm512x->pll_out) + return 0; /* no PLL to bypass, force SCK as DAC input */ + + if (pllin_rate % osr_rate) + return 0; /* futile, quit early */ + + /* run DAC no faster than 6144000 Hz */ + for (dac_rate = rounddown(6144000, osr_rate); + dac_rate; + dac_rate -= osr_rate) { + + if (pllin_rate / dac_rate > 128) + return 0; /* DAC divider would be too big */ + + if (!(pllin_rate % dac_rate)) + return dac_rate; + + dac_rate -= osr_rate; + } + + return 0; +} + static int pcm512x_set_dividers(struct snd_soc_dai *dai, struct snd_pcm_hw_params *params) { @@ -694,6 +727,7 @@ static int pcm512x_set_dividers(struct snd_soc_dai *dai, unsigned long bclk_rate; unsigned long sample_rate; unsigned long osr_rate; + unsigned long dacsrc_rate; int bclk_div; int lrclk_div; int dsp_div; @@ -701,11 +735,10 @@ static int pcm512x_set_dividers(struct snd_soc_dai *dai, unsigned long dac_rate; int ncp_div; int osr_div; - unsigned long dac_mul; - unsigned long sck_mul; int ret; int idac; int fssp; + int gpio; lrclk_div = pcm512x_params_to_frame_size(params); if (lrclk_div == 0) { @@ -794,31 +827,72 @@ static int pcm512x_set_dividers(struct snd_soc_dai *dai, /* run DSP no faster than 50 MHz */ dsp_div = mck_rate > 50000000 ? 2 : 1; - /* run DAC no faster than 6144000 Hz */ - dac_mul = 6144000 / osr_rate; - sck_mul = sck_rate / osr_rate; - for (; dac_mul; dac_mul--) { - if (!(sck_mul % dac_mul)) - break; - } - if (!dac_mul) { - dev_err(dev, "Failed to find DAC rate\n"); - return -EINVAL; - } + dac_rate = pcm512x_pllin_dac_rate(dai, osr_rate, pllin_rate); + if (dac_rate) { + /* the desired clock rate is "compatible" with the pll input + * clock, so use that clock as dac input instead of the pll + * output clock since the pll will introduce jitter and thus + * noise. + */ + dev_dbg(dev, "using pll input as dac input\n"); + ret = regmap_update_bits(pcm512x->regmap, PCM512x_DAC_REF, + PCM512x_SDAC, PCM512x_SDAC_GPIO); + if (ret != 0) { + dev_err(codec->dev, + "Failed to set gpio as dacref: %d\n", ret); + return ret; + } - dac_rate = dac_mul * osr_rate; - dev_dbg(dev, "dac_rate %lu sample_rate %lu\n", dac_rate, sample_rate); + gpio = PCM512x_GREF_GPIO1 + pcm512x->pll_in - 1; + ret = regmap_update_bits(pcm512x->regmap, PCM512x_GPIO_DACIN, + PCM512x_GREF, gpio); + if (ret != 0) { + dev_err(codec->dev, + "Failed to set gpio %d as dacin: %d\n", + pcm512x->pll_in, ret); + return ret; + } + + dacsrc_rate = pllin_rate; + } else { + /* run DAC no faster than 6144000 Hz */ + unsigned long dac_mul = 6144000 / osr_rate; + unsigned long sck_mul = sck_rate / osr_rate; + + for (; dac_mul; dac_mul--) { + if (!(sck_mul % dac_mul)) + break; + } + if (!dac_mul) { + dev_err(dev, "Failed to find DAC rate\n"); + return -EINVAL; + } - dac_div = DIV_ROUND_CLOSEST(sck_rate, dac_rate); + dac_rate = dac_mul * osr_rate; + dev_dbg(dev, "dac_rate %lu sample_rate %lu\n", + dac_rate, sample_rate); + + ret = regmap_update_bits(pcm512x->regmap, PCM512x_DAC_REF, + PCM512x_SDAC, PCM512x_SDAC_SCK); + if (ret != 0) { + dev_err(codec->dev, + "Failed to set sck as dacref: %d\n", ret); + return ret; + } + + dacsrc_rate = sck_rate; + } + + dac_div = DIV_ROUND_CLOSEST(dacsrc_rate, dac_rate); if (dac_div > 128) { dev_err(dev, "Failed to find DAC divider\n"); return -EINVAL; } - ncp_div = DIV_ROUND_CLOSEST(sck_rate / dac_div, 1536000); - if (ncp_div > 128 || sck_rate / dac_div / ncp_div > 2048000) { + ncp_div = DIV_ROUND_CLOSEST(dacsrc_rate / dac_div, 1536000); + if (ncp_div > 128 || dacsrc_rate / dac_div / ncp_div > 2048000) { /* run NCP no faster than 2048000 Hz, but why? */ - ncp_div = DIV_ROUND_UP(sck_rate / dac_div, 2048000); + ncp_div = DIV_ROUND_UP(dacsrc_rate / dac_div, 2048000); if (ncp_div > 128) { dev_err(dev, "Failed to find NCP divider\n"); return -EINVAL; @@ -1033,13 +1107,6 @@ static int pcm512x_hw_params(struct snd_pcm_substream *substream, if (ret != 0) return ret; - ret = regmap_update_bits(pcm512x->regmap, PCM512x_DAC_REF, - PCM512x_SDAC, PCM512x_SDAC_SCK); - if (ret != 0) { - dev_err(codec->dev, "Failed to set sck as dacref: %d\n", ret); - return ret; - } - if (pcm512x->pll_out) { ret = regmap_update_bits(pcm512x->regmap, PCM512x_PLL_REF, PCM512x_SREF, PCM512x_SREF_GPIO); diff --git a/sound/soc/codecs/pcm512x.h b/sound/soc/codecs/pcm512x.h index eba5adc2cdb1..b7c310207223 100644 --- a/sound/soc/codecs/pcm512x.h +++ b/sound/soc/codecs/pcm512x.h @@ -38,6 +38,7 @@ #define PCM512x_MASTER_MODE (PCM512x_PAGE_BASE(0) + 12) #define PCM512x_PLL_REF (PCM512x_PAGE_BASE(0) + 13) #define PCM512x_DAC_REF (PCM512x_PAGE_BASE(0) + 14) +#define PCM512x_GPIO_DACIN (PCM512x_PAGE_BASE(0) + 16) #define PCM512x_GPIO_PLLIN (PCM512x_PAGE_BASE(0) + 18) #define PCM512x_SYNCHRONIZE (PCM512x_PAGE_BASE(0) + 19) #define PCM512x_PLL_COEFF_0 (PCM512x_PAGE_BASE(0) + 20) @@ -162,8 +163,9 @@ #define PCM512x_SDAC_PLL (1 << 4) #define PCM512x_SDAC_SCK (3 << 4) #define PCM512x_SDAC_BCK (4 << 4) +#define PCM512x_SDAC_GPIO (5 << 4) -/* Page 0, Register 18 - GPIO source for PLL */ +/* Page 0, Register 16, 18 - GPIO source for DAC, PLL */ #define PCM512x_GREF (7 << 0) #define PCM512x_GREF_SHIFT 0 #define PCM512x_GREF_GPIO1 (0 << 0)