ASoC: max98357a: use mdelay for sdmode-delay

max98357a_daiops_trigger() is possible to be called in atomic context if
the .nonatomic flag is equal to 0 in the DAI links.

When cancel_delayed_work_sync() in max98357a_daiops_trigger() is called
in atomic context, kernel emits the following message: "BUG: sleeping
function called from invalid context".

According to the DT binding document, value less than or equal to 5ms of
sdmod-delay should be sufficient to avoid the pop noise.  Use mdelay
(i.e. busy loop) for such low delay should be acceptable.

Fixes: cec5b01f8f1c ("ASoC: max98357a: avoid speaker pop when playback
startup")

Signed-off-by: Tzung-Bi Shih <tzungbi@google.com>
Link: https://lore.kernel.org/r/20190708141901.68797-1-tzungbi@google.com
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/sound/soc/codecs/max98357a.c b/sound/soc/codecs/max98357a.c
index 6f0e28f..16313b9 100644 (file)
--- a/sound/soc/codecs/max98357a.c
+++ b/sound/soc/codecs/max98357a.c
@@ -20,20 +20,10 @@
 #include <sound/soc-dapm.h>
 
 struct max98357a_priv {
-       struct delayed_work enable_sdmode_work;
        struct gpio_desc *sdmode;
        unsigned int sdmode_delay;
 };
 
-static void max98357a_enable_sdmode_work(struct work_struct *work)
-{
-       struct max98357a_priv *max98357a =
-       container_of(work, struct max98357a_priv,
-                       enable_sdmode_work.work);
-
-       gpiod_set_value(max98357a->sdmode, 1);
-}
-
 static int max98357a_daiops_trigger(struct snd_pcm_substream *substream,
                int cmd, struct snd_soc_dai *dai)
 {
@@ -46,14 +36,12 @@ static int max98357a_daiops_trigger(struct snd_pcm_substream *substream,
        case SNDRV_PCM_TRIGGER_START:
        case SNDRV_PCM_TRIGGER_RESUME:
        case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
-               queue_delayed_work(system_power_efficient_wq,
-                               &max98357a->enable_sdmode_work,
-                               msecs_to_jiffies(max98357a->sdmode_delay));
+               mdelay(max98357a->sdmode_delay);
+               gpiod_set_value(max98357a->sdmode, 1);
                break;
        case SNDRV_PCM_TRIGGER_STOP:
        case SNDRV_PCM_TRIGGER_SUSPEND:
        case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
-               cancel_delayed_work_sync(&max98357a->enable_sdmode_work);
                gpiod_set_value(max98357a->sdmode, 0);
                break;
        }
@@ -112,30 +100,25 @@ static int max98357a_platform_probe(struct platform_device *pdev)
        int ret;
 
        max98357a = devm_kzalloc(&pdev->dev, sizeof(*max98357a), GFP_KERNEL);
-
        if (!max98357a)
                return -ENOMEM;
 
        max98357a->sdmode = devm_gpiod_get_optional(&pdev->dev,
                                "sdmode", GPIOD_OUT_LOW);
-
        if (IS_ERR(max98357a->sdmode))
                return PTR_ERR(max98357a->sdmode);
 
        ret = device_property_read_u32(&pdev->dev, "sdmode-delay",
                                        &max98357a->sdmode_delay);
-
        if (ret) {
                max98357a->sdmode_delay = 0;
                dev_dbg(&pdev->dev,
-                       "no optional property 'sdmode-delay' found, default: no delay\n");
+                       "no optional property 'sdmode-delay' found, "
+                       "default: no delay\n");
        }
 
        dev_set_drvdata(&pdev->dev, max98357a);
 
-       INIT_DELAYED_WORK(&max98357a->enable_sdmode_work,
-                               max98357a_enable_sdmode_work);
-
        return devm_snd_soc_register_component(&pdev->dev,
                        &max98357a_component_driver,
                        &max98357a_dai_driver, 1);