ASoC: es8316: fix redundant codes of clock

This patch removes redundant null checks for optional MCLK clock.
And fix DT binding document for changing clock property to optional
from required.

Signed-off-by: Katsuhiro Suzuki <katsuhiro@katsuster.net>
Link: https://lore.kernel.org/r/20190907163653.9382-1-katsuhiro@katsuster.net
Signed-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/everest,es8316.txt

@@ -6,6 +6,9 @@ Required properties:
 
   - compatible  : should be "everest,es8316"
   - reg : the I2C address of the device for I2C
+
+Optional properties:
+
   - clocks : a list of phandle, should contain entries for clock-names
   - clock-names : should include as follows:
          "mclk" : master clock (MCLK) of the device

sound/soc/codecs/es8316.c

@@ -370,11 +370,9 @@ static int es8316_set_dai_sysclk(struct snd_soc_dai *codec_dai,
 	if (freq == 0)
 		return 0;
 
-	if (es8316->mclk) {
-		ret = clk_set_rate(es8316->mclk, freq);
-		if (ret)
-			return ret;
-	}
+	ret = clk_set_rate(es8316->mclk, freq);
+	if (ret)
+		return ret;
 
 	/* Limit supported sample rates to ones that can be autodetected
 	 * by the codec running in slave mode.
@@ -709,20 +707,18 @@ static int es8316_probe(struct snd_soc_component *component)
 
 	es8316->component = component;
 
-	es8316->mclk = devm_clk_get(component->dev, "mclk");
-	if (PTR_ERR(es8316->mclk) == -EPROBE_DEFER)
-		return -EPROBE_DEFER;
+	es8316->mclk = devm_clk_get_optional(component->dev, "mclk");
 	if (IS_ERR(es8316->mclk)) {
-		dev_err(component->dev, "clock is invalid, ignored\n");
-		es8316->mclk = NULL;
+		dev_err(component->dev, "unable to get mclk\n");
+		return PTR_ERR(es8316->mclk);
 	}
+	if (!es8316->mclk)
+		dev_warn(component->dev, "assuming static mclk\n");
 
-	if (es8316->mclk) {
-		ret = clk_prepare_enable(es8316->mclk);
-		if (ret) {
-			dev_err(component->dev, "unable to enable clock\n");
-			return ret;
-		}
+	ret = clk_prepare_enable(es8316->mclk);
+	if (ret) {
+		dev_err(component->dev, "unable to enable mclk\n");
+		return ret;
 	}
 
 	/* Reset codec and enable current state machine */
@@ -751,8 +747,7 @@ static void es8316_remove(struct snd_soc_component *component)
 {
 	struct es8316_priv *es8316 = snd_soc_component_get_drvdata(component);
 
-	if (es8316->mclk)
-		clk_disable_unprepare(es8316->mclk);
+	clk_disable_unprepare(es8316->mclk);
 }
 
 static const struct snd_soc_component_driver soc_component_dev_es8316 = {