When being powered on, either initially on probe or when resuming from suspend, the wm8971 configures the device for quick output capacitor charging. Since the charging can take a rather long time (up to multiple seconds) it is done asynchronously without blocking. A delayed work item is run once the charging is finished and the device is switched to the target bias level.
This all done asynchronously to the regular DAPM sequence accessing the same data structures and registers without any looking, which can lead to race conditions. Furthermore this potentially delays the start of stream on the CODEC while the rest of the system is already up and running, meaning the first bytes of audio are lost. It also does no comply with the assumption of the DAPM core that if set_bias_level() returned successfully the device will be at the requested bias level.
This patch slightly refactors things and makes sure that the caps charging is properly integrated into the DAPM sequence. When transitioning from SND_SOC_BIAS_OFF to SND_SOC_BIAS_STANDBY the part will be put into fast charging mode and a work item will be scheduled that puts it back into standby charging once the charging period has elapsed. If a playback or capture stream is started while charging is in progress the driver will now wait in SND_SOC_BIAS_PREPARE until the charging is done. This makes sure that charging is done asynchronously in the background when the chip is idle, but at the same time makes sure that playback/capture is not started before the charging is done.
Signed-off-by: Lars-Peter Clausen lars@metafoo.de --- sound/soc/codecs/wm8971.c | 71 +++++++++++++++++++++-------------------------- 1 file changed, 31 insertions(+), 40 deletions(-)
diff --git a/sound/soc/codecs/wm8971.c b/sound/soc/codecs/wm8971.c index 44baacd..4ab034d 100644 --- a/sound/soc/codecs/wm8971.c +++ b/sound/soc/codecs/wm8971.c @@ -34,6 +34,8 @@ /* codec private data */ struct wm8971_priv { unsigned int sysclk; + struct delayed_work charge_work; + struct regmap *regmap; };
/* @@ -550,9 +552,19 @@ static int wm8971_mute(struct snd_soc_dai *dai, int mute) return 0; }
+static void wm8971_charge_work(struct work_struct *work) +{ + struct wm8971_priv *wm8971 = + container_of(work, struct wm8971_priv, charge_work.work); + + /* Set to 500k */ + regmap_update_bits(wm8971->regmap, WM8971_PWR1, 0x0180, 0x0100); +} + static int wm8971_set_bias_level(struct snd_soc_codec *codec, enum snd_soc_bias_level level) { + struct wm8971_priv *wm8971 = snd_soc_codec_get_drvdata(codec); u16 pwr_reg = snd_soc_read(codec, WM8971_PWR1) & 0xfe3e;
switch (level) { @@ -561,15 +573,24 @@ static int wm8971_set_bias_level(struct snd_soc_codec *codec, snd_soc_write(codec, WM8971_PWR1, pwr_reg | 0x00c1); break; case SND_SOC_BIAS_PREPARE: + /* Wait until fully charged */ + flush_delayed_work(&wm8971->charge_work); break; case SND_SOC_BIAS_STANDBY: - if (codec->dapm.bias_level == SND_SOC_BIAS_OFF) + if (codec->dapm.bias_level == SND_SOC_BIAS_OFF) { snd_soc_cache_sync(codec); + /* charge output caps - set vmid to 5k for quick power up */ + snd_soc_write(codec, WM8971_PWR1, pwr_reg | 0x01c0); + queue_delayed_work(system_power_efficient_wq, + &wm8971->charge_work, msecs_to_jiffies(1000)); + } else { + /* mute dac and set vmid to 500k, enable VREF */ + snd_soc_write(codec, WM8971_PWR1, pwr_reg | 0x0140); + }
- /* mute dac and set vmid to 500k, enable VREF */ - snd_soc_write(codec, WM8971_PWR1, pwr_reg | 0x0140); break; case SND_SOC_BIAS_OFF: + cancel_delayed_work_sync(&wm8971->charge_work); snd_soc_write(codec, WM8971_PWR1, 0x0001); break; } @@ -608,15 +629,6 @@ static struct snd_soc_dai_driver wm8971_dai = { .ops = &wm8971_dai_ops, };
-static void wm8971_work(struct work_struct *work) -{ - struct snd_soc_dapm_context *dapm = - container_of(work, struct snd_soc_dapm_context, - delayed_work.work); - struct snd_soc_codec *codec = snd_soc_dapm_to_codec(dapm); - wm8971_set_bias_level(codec, codec->dapm.bias_level); -} - static int wm8971_suspend(struct snd_soc_codec *codec) { wm8971_set_bias_level(codec, SND_SOC_BIAS_OFF); @@ -625,39 +637,19 @@ static int wm8971_suspend(struct snd_soc_codec *codec)
static int wm8971_resume(struct snd_soc_codec *codec) { - u16 reg; - wm8971_set_bias_level(codec, SND_SOC_BIAS_STANDBY); - - /* charge wm8971 caps */ - if (codec->dapm.suspend_bias_level == SND_SOC_BIAS_ON) { - reg = snd_soc_read(codec, WM8971_PWR1) & 0xfe3e; - snd_soc_write(codec, WM8971_PWR1, reg | 0x01c0); - codec->dapm.bias_level = SND_SOC_BIAS_ON; - queue_delayed_work(system_power_efficient_wq, - &codec->dapm.delayed_work, - msecs_to_jiffies(1000)); - } - return 0; }
static int wm8971_probe(struct snd_soc_codec *codec) { - int ret = 0; - u16 reg; + struct wm8971_priv *wm8971 = snd_soc_codec_get_drvdata(codec);
- INIT_DELAYED_WORK(&codec->dapm.delayed_work, wm8971_work); + INIT_DELAYED_WORK(&wm8971->charge_work, wm8971_charge_work);
wm8971_reset(codec);
- /* charge output caps - set vmid to 5k for quick power up */ - reg = snd_soc_read(codec, WM8971_PWR1) & 0xfe3e; - snd_soc_write(codec, WM8971_PWR1, reg | 0x01c0); - codec->dapm.bias_level = SND_SOC_BIAS_STANDBY; - queue_delayed_work(system_power_efficient_wq, - &codec->dapm.delayed_work, - msecs_to_jiffies(1000)); + wm8971_set_bias_level(codec, SND_SOC_BIAS_STANDBY);
/* set the update bits */ snd_soc_update_bits(codec, WM8971_LDAC, 0x0100, 0x0100); @@ -669,7 +661,7 @@ static int wm8971_probe(struct snd_soc_codec *codec) snd_soc_update_bits(codec, WM8971_LINVOL, 0x0100, 0x0100); snd_soc_update_bits(codec, WM8971_RINVOL, 0x0100, 0x0100);
- return ret; + return 0; }
@@ -710,7 +702,6 @@ static int wm8971_i2c_probe(struct i2c_client *i2c, const struct i2c_device_id *id) { struct wm8971_priv *wm8971; - struct regmap *regmap; int ret;
wm8971 = devm_kzalloc(&i2c->dev, sizeof(struct wm8971_priv), @@ -718,9 +709,9 @@ static int wm8971_i2c_probe(struct i2c_client *i2c, if (wm8971 == NULL) return -ENOMEM;
- regmap = devm_regmap_init_i2c(i2c, &wm8971_regmap); - if (IS_ERR(regmap)) - return PTR_ERR(regmap); + wm8971->regmap = devm_regmap_init_i2c(i2c, &wm8971_regmap); + if (IS_ERR(wm8971->regmap)) + return PTR_ERR(wm8971->regmap);
i2c_set_clientdata(i2c, wm8971);