Re: [alsa-devel] [PATCH 2/3] ASoC: tas571x: New driver for TI TAS571x power amplifiers

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On 04/15/2015 11:42 PM, Kevin Cernekee wrote:
Introduce a new codec driver for the Texas Instruments
TAS5711/TAS5717/TAS5719 power amplifier chips.  These chips are typically
used to take an I2S digital audio input and drive 10-20W into a pair of
speakers.

Signed-off-by: Kevin Cernekee <cernekee@xxxxxxxxxxxx>

Looks pretty good. Comments inlune.

[...]
-obj-$(CONFIG_SND_SOC_TAS5086)	+= snd-soc-tas5086.o

Accidentally removed line

+obj-$(CONFIG_SND_SOC_TAS571X)	+= snd-soc-tas571x.o
[...]
+++ b/sound/soc/codecs/tas571x.c
@@ -0,0 +1,456 @@
+/*
+ * TAS571x amplifier audio driver
+ *
+ * Copyright (C) 2015 Google, Inc.
+ * Copyright (c) 2013 Daniel Mack <zonque@xxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/gpio/consumer.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of_gpio.h>

There is no of specific GPIO code in the driver.

[...]
+
+static int tas571x_set_bias_level(struct snd_soc_codec *codec,
+				  enum snd_soc_bias_level level)
+{
+	struct tas571x_private *priv = snd_soc_codec_get_drvdata(codec);
+	int ret, assert_pdn = 0;
+
+	if (priv->bias_level == level)
+		return 0;

The core already takes care that this function is only called if there is a actual change.

+
+	switch (level) {
+	case SND_SOC_BIAS_PREPARE:
+		if (!IS_ERR(priv->mclk)) {
+			ret = clk_prepare_enable(priv->mclk);
+			if (ret) {
+				dev_err(codec->dev,
+					"Failed to enable master clock\n");
+				return ret;
+			}
+		}
+
+		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;
+
+		if (!IS_ERR(priv->mclk))
+			clk_disable_unprepare(priv->mclk);
+		break;
+	case SND_SOC_BIAS_ON:
+		break;
+	case SND_SOC_BIAS_OFF:
+		/* Note that this kills I2C accesses. */
+		assert_pdn = 1;
+		break;
+	}
+
+	if (!IS_ERR(priv->pdn_gpio))
+		gpiod_set_value(priv->pdn_gpio, !assert_pdn);
+
+	priv->bias_level = level;

This should update codec->dapm.bias_level, otherwise the core will become confused about the actual level.

+	return 0;
+}
+
[...]
+static const unsigned int tas5711_volume_tlv[] = {
+	TLV_DB_RANGE_HEAD(1),
+	0, 0xff, TLV_DB_SCALE_ITEM(-10350, 50, 1),
+};

For TLVs with a single item use DECLARE_TLV_DB_SCALE()

+
[...]
+static const unsigned int tas5717_volume_tlv[] = {
+	TLV_DB_RANGE_HEAD(1),
+	0x000, 0x1ff, TLV_DB_SCALE_ITEM(-10375, 25, 0),
+};

Same here.

[...]
+static int tas571x_i2c_probe(struct i2c_client *client,
+			     const struct i2c_device_id *id)
+{
+	struct tas571x_private *priv;
+	struct device *dev = &client->dev;
+	int i;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+	i2c_set_clientdata(client, priv);
+
+	priv->mclk = devm_clk_get(dev, "mclk");
+	if (PTR_ERR(priv->mclk) == -EPROBE_DEFER)
+		return -EPROBE_DEFER;

If you want to make the clock optional use

	if (PTR_ERR(priv->mclk) == -ENOENT)
		return PTR_ERR(priv->mclk);

This makes sure that the case where the clock is specified, but there is a error with the specification (e.g. incorrect DT cells) is handled properly.

+
+	for (i = 0; i < TAS571X_NUM_SUPPLIES; i++)
+		priv->supplies[i].supply = tas571x_supply_names[i];
+
+	/*
+	 * This will fall back to the dummy regulator if nothing is specified
+	 * in DT.
+	 */
+	if (devm_regulator_bulk_get(dev, TAS571X_NUM_SUPPLIES,
+				    priv->supplies)) {

Move the function outside the if condition and also pass the error condition to the caller. (And print it)

+		dev_err(dev, "Failed to get supplies\n");
+		return -EINVAL;
+	}
+	if (regulator_bulk_enable(TAS571X_NUM_SUPPLIES, priv->supplies)) {

Same here.

+		dev_err(dev, "Failed to enable supplies\n");
+		return -EINVAL;
+	}
+
+	priv->regmap = devm_regmap_init(dev, NULL, client, &tas571x_regmap);
+	if (IS_ERR(priv->regmap))
+		return PTR_ERR(priv->regmap);
+
+	priv->pdn_gpio = devm_gpiod_get(dev, "pdn");

devm_gpiod_get_optional() ?

Using gpiod_get without specifying the direction flags is deprecated. Should be

... = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);

and then drop the gpiod_direction_output().


+	if (!IS_ERR(priv->pdn_gpio)) {
+		gpiod_direction_output(priv->pdn_gpio, 1);
+	} else if (PTR_ERR(priv->pdn_gpio) != -ENOENT &&
+		   PTR_ERR(priv->pdn_gpio) != -ENOSYS) {
+		dev_warn(dev, "error requesting pdn_gpio: %ld\n",
+			 PTR_ERR(priv->pdn_gpio));

If the GPIO can't be requested and it is not a optional GPIO that should be treated as an error.

+	}
+
+	priv->reset_gpio = devm_gpiod_get(dev, "reset");

Same as for the pdn_gpio.

+	if (!IS_ERR(priv->reset_gpio)) {
+		gpiod_direction_output(priv->reset_gpio, 0);
+		usleep_range(100, 200);
+		gpiod_set_value(priv->reset_gpio, 1);
+		usleep_range(12000, 20000);
+	} else if (PTR_ERR(priv->reset_gpio) != -ENOENT &&
+		   PTR_ERR(priv->reset_gpio) != -ENOSYS) {
+		dev_warn(dev, "error requesting reset_gpio: %ld\n",
+			 PTR_ERR(priv->reset_gpio));

Same as for the pdn_gpio.

+	}
+
+	priv->bias_level = SND_SOC_BIAS_STANDBY;
+
+	if (regmap_write(priv->regmap, TAS571X_OSC_TRIM_REG, 0))
+		return -EIO;
+
+	if (tas571x_set_shutdown(priv, true))
+		return -EIO;
+
+	memcpy(&priv->codec_driver, &tas571x_codec, sizeof(priv->codec_driver));
+	priv->dev_id = id->driver_data;
+
+	switch (id->driver_data) {
+	case TAS571X_ID_5711:
+		priv->codec_driver.controls = tas5711_controls;
+		priv->codec_driver.num_controls = ARRAY_SIZE(tas5711_controls);
+		break;
+	case TAS571X_ID_5717:
+	case TAS571X_ID_5719:
+		priv->codec_driver.controls = tas5717_controls;
+		priv->codec_driver.num_controls = ARRAY_SIZE(tas5717_controls);
+
+		/*
+		 * 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;
+
+		break;
+	}

Typically when a driver supports multiple chips with different control sets the snd_soc_codec_driver implements a probe callback in which the correct controls are registered.

+
+	return snd_soc_register_codec(&client->dev, &priv->codec_driver,
+				      &tas571x_dai, 1);
+}
+
[...]
+
+static const struct of_device_id tas571x_of_match[] = {
+	{ .compatible = "ti,tas5711", },
+	{ .compatible = "ti,tas5717", },
+	{ .compatible = "ti,tas5719", },

You should also specify the id data for the of table and get it from the of_data if of_node is non NULL in the probe function. I know that it works without, but that is a bit of a unintentional side-effect and might change in the future.

+	{ }
+};
+MODULE_DEVICE_TABLE(of, tas571x_of_match);
--
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