Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754071AbbDRQRF (ORCPT ); Sat, 18 Apr 2015 12:17:05 -0400 Received: from mail-wi0-f179.google.com ([209.85.212.179]:35684 "EHLO mail-wi0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753960AbbDRQRC (ORCPT ); Sat, 18 Apr 2015 12:17:02 -0400 MIME-Version: 1.0 In-Reply-To: <20150418113632.GE26185@sirena.org.uk> References: <1429134141-17924-1-git-send-email-cernekee@chromium.org> <1429134141-17924-2-git-send-email-cernekee@chromium.org> <20150418113632.GE26185@sirena.org.uk> From: Kevin Cernekee Date: Sat, 18 Apr 2015 09:16:36 -0700 Message-ID: Subject: Re: [PATCH 2/3] ASoC: tas571x: New driver for TI TAS571x power amplifiers To: Mark Brown Cc: lgirdwood@gmail.com, dgreid@chromium.org, Andrew Bresticker , Olof Johansson , alsa-devel@alsa-project.org, devicetree@vger.kernel.org, "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3697 Lines: 94 On Sat, Apr 18, 2015 at 4:36 AM, Mark Brown wrote: > On Wed, Apr 15, 2015 at 02:42:20PM -0700, Kevin Cernekee wrote: >> +static int tas571x_set_sysclk(struct snd_soc_dai *dai, >> + int clk_id, unsigned int freq, int dir) >> +{ >> + /* >> + * TAS5717 datasheet pg 21: "The DAP can autodetect and set the >> + * internal clock-control logic to the appropriate settings for all >> + * supported clock rates as defined in the clock control register." >> + */ >> + return 0; >> +} > > Remove empty functions, at best they waste space at worst they break > things. Without the empty function, we run into problems with drivers that abort when they get -ENOTSUPP here: sound/soc/atmel/atmel_wm8904.c: ret = snd_soc_dai_set_sysclk(codec_dai, WM8904_CLK_FLL, sound/soc/atmel/atmel_wm8904.c- 0, SND_SOC_CLOCK_IN); sound/soc/atmel/atmel_wm8904.c- if (ret < 0) { sound/soc/atmel/atmel_wm8904.c- pr_err("%s -failed to set wm8904 SYSCLK\n", __func__); sound/soc/atmel/atmel_wm8904.c- return ret; sound/soc/atmel/atmel_wm8904.c- } Is there a stub version that I can use instead? Nothing jumped out at me when looking at the other codec drivers. >> +static int tas571x_set_shutdown(struct tas571x_private *priv, bool is_shutdown) >> +{ >> + return regmap_update_bits(priv->regmap, TAS571X_SYS_CTRL_2_REG, >> + TAS571X_SYS_CTRL_2_SDN_MASK, >> + is_shutdown ? TAS571X_SYS_CTRL_2_SDN_MASK : 0); >> +} > >> + ret = tas571x_set_shutdown(priv, false); >> + if (ret) >> + return ret; >> + break; >> + case SND_SOC_BIAS_STANDBY: >> + ret = tas571x_set_shutdown(priv, true); >> + if (ret) >> + return ret; > > This looks like it'd be clearer just as direct register updates, I'm not > sure a function to set a single bit is addinng much. It might be useful if another tas571x variant put the bit somewhere else, but that hasn't happened yet so I can nuke the helper function for now. >> + case SND_SOC_BIAS_OFF: >> + /* Note that this kills I2C accesses. */ >> + assert_pdn = 1; > > No, the GPIO set associated with it kills I2C access. I'd also expect > to see the regmap being marked cache only before we do this and a resync > of the register map when we power back up (assuming that is actually a > power down). Hmm, not sure if this actually resets the registers back to power-on defaults, but I'll check. >> + /* >> + * The master volume defaults to 0x3ff (mute), but we ignore >> + * (zero) the LSB because the hardware step size is 0.125 dB >> + * and TLV_DB_SCALE_ITEM has a resolution of 0.01 dB. >> + */ >> + if (regmap_write(priv->regmap, TAS571X_MVOL_REG, 0x3fe)) >> + return -EIO; > > I don't understand this - is the LSB a mute bit or sommething? The 10-bit master volume field on 5717/5719 works like: 0x3ff: MUTE (power-on default) 0x3fe: -103.750 dB 0x3fd: -103.625 dB [lots more options, in 0.125 dB increments] 0x001: 23.875 dB 0x000: 24.000 dB Since we only have a resolution of 0.01 dB, the driver forces the LSB to 0 and uses 0.25 dB increments instead of 0.125 dB. Mute is handled through the dedicated per-channel soft mute register bits instead of the 0x3ff volume setting. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/