@@ -15,6 +15,7 @@
*/
#include <linux/clk.h>
+#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/slab.h>
#include <linux/of_device.h>
@@ -95,6 +96,9 @@ struct ak4613_priv {
struct mutex lock;
const struct ak4613_interface *iface;
struct snd_pcm_hw_constraint_list constraint;
+ struct work_struct dummy_write_work;
+ struct snd_soc_component *component;
+ unsigned int rate;
unsigned int sysclk;
unsigned int fmt;
@@ -392,6 +396,7 @@ static int ak4613_dai_hw_params(struct snd_pcm_substream *substream,
default:
return -EINVAL;
}
+ priv->rate = rate;
/*
* FIXME
@@ -467,11 +472,83 @@ static int ak4613_set_bias_level(struct snd_soc_codec *codec,
return 0;
}
+static void ak4613_dummy_write(struct work_struct *work)
+{
+ struct ak4613_priv *priv = container_of(work,
+ struct ak4613_priv,
+ dummy_write_work);
+ struct snd_soc_component *component = priv->component;
+ unsigned int mgmt1;
+ unsigned int mgmt3;
+
+ /*
+ * PW_MGMT1 / PW_MGMT3 needs dummy write at least after 5 LR clocks
+ *
+ * Note
+ *
+ * To avoid extra delay, we want to avoid preemption here,
+ * but we can't. Because it uses I2C access which is using IRQ
+ * and sleep. Thus, delay might be more than 5 LR clocks
+ * see also
+ * ak4613_dai_trigger()
+ */
+ udelay(5000000 / priv->rate);
+
+ snd_soc_component_read(component, PW_MGMT1, &mgmt1);
+ snd_soc_component_read(component, PW_MGMT3, &mgmt3);
+
+ snd_soc_component_write(component, PW_MGMT1, mgmt1);
+ snd_soc_component_write(component, PW_MGMT3, mgmt3);
+}
+
+static int ak4613_dai_trigger(struct snd_pcm_substream *substream, int cmd,
+ struct snd_soc_dai *dai)
+{
+ struct snd_soc_codec *codec = dai->codec;
+ struct ak4613_priv *priv = snd_soc_codec_get_drvdata(codec);
+
+ /*
+ * FIXME
+ *
+ * PW_MGMT1 / PW_MGMT3 needs dummy write at least after 5 LR clocks
+ * from Power Down Release. Otherwise, Playback volume will be 0dB.
+ * To avoid complex multiple delay/dummy_write method from
+ * ak4613_set_bias_level() / SND_SOC_DAPM_DAC_E("DACx", ...),
+ * call it once here.
+ *
+ * But, unfortunately, we can't "write" here because here is atomic
+ * context (It uses I2C access for writing).
+ * Thus, use schedule_work() to switching to normal context
+ * immediately.
+ *
+ * Note
+ *
+ * Calling ak4613_dummy_write() function might be delayed.
+ * In such case, ak4613 volume might be temporarily 0dB when
+ * beggining of playback.
+ * see also
+ * ak4613_dummy_write()
+ */
+
+ if ((cmd != SNDRV_PCM_TRIGGER_START) &&
+ (cmd != SNDRV_PCM_TRIGGER_RESUME))
+ return 0;
+
+ if (substream->stream != SNDRV_PCM_STREAM_PLAYBACK)
+ return 0;
+
+ priv->component = &codec->component;
+ schedule_work(&priv->dummy_write_work);
+
+ return 0;
+}
+
static const struct snd_soc_dai_ops ak4613_dai_ops = {
.startup = ak4613_dai_startup,
.shutdown = ak4613_dai_shutdown,
.set_sysclk = ak4613_dai_set_sysclk,
.set_fmt = ak4613_dai_set_fmt,
+ .trigger = ak4613_dai_trigger,
.hw_params = ak4613_dai_hw_params,
};
@@ -590,6 +667,7 @@ static int ak4613_i2c_probe(struct i2c_client *i2c,
priv->iface = NULL;
priv->cnt = 0;
priv->sysclk = 0;
+ INIT_WORK(&priv->dummy_write_work, ak4613_dummy_write);
mutex_init(&priv->lock);