[PATCH] ASoC: ep93xx: Fix unchecked clk_prepare_enable() and add rollback on failure

[Jihed Chaibi]

ep93xx_i2s_enable() calls clk_prepare_enable() on three clocks in
sequence (mclk, sclk, lrclk) without checking the return value of any
of them. If an intermediate enable fails, the clocks that were already
enabled are never rolled back, leaking them until the next disable cycle
— which may never come if the stream never started cleanly.

Change ep93xx_i2s_enable() from void to int. Add error checking after
each clk_prepare_enable() call and unwind already-enabled clocks on
failure. Propagate the error through ep93xx_i2s_startup() and
ep93xx_i2s_resume(), both of which already return int.

Signed-off-by: Jihed Chaibi <jihed.chaibi.dev@xxxxxxxxx>
---
 sound/soc/cirrus/ep93xx-i2s.c | 34 ++++++++++++++++++++++++----------
 1 file changed, 24 insertions(+), 10 deletions(-)

diff --git a/sound/soc/cirrus/ep93xx-i2s.c b/sound/soc/cirrus/ep93xx-i2s.c
index cca01c03f048..5dba741594fa 100644
--- a/sound/soc/cirrus/ep93xx-i2s.c
+++ b/sound/soc/cirrus/ep93xx-i2s.c
@@ -91,16 +91,28 @@ static inline unsigned ep93xx_i2s_read_reg(struct ep93xx_i2s_info *info,
 	return __raw_readl(info->regs + reg);
 }
 
-static void ep93xx_i2s_enable(struct ep93xx_i2s_info *info, int stream)
+static int ep93xx_i2s_enable(struct ep93xx_i2s_info *info, int stream)
 {
 	unsigned base_reg;
+	int err;
 
 	if ((ep93xx_i2s_read_reg(info, EP93XX_I2S_TX0EN) & 0x1) == 0 &&
 	    (ep93xx_i2s_read_reg(info, EP93XX_I2S_RX0EN) & 0x1) == 0) {
 		/* Enable clocks */
-		clk_prepare_enable(info->mclk);
-		clk_prepare_enable(info->sclk);
-		clk_prepare_enable(info->lrclk);
+		err = clk_prepare_enable(info->mclk);
+		if (err)
+			return err;
+		err = clk_prepare_enable(info->sclk);
+		if (err) {
+			clk_disable_unprepare(info->mclk);
+			return err;
+		}
+		err = clk_prepare_enable(info->lrclk);
+		if (err) {
+			clk_disable_unprepare(info->sclk);
+			clk_disable_unprepare(info->mclk);
+			return err;
+		}
 
 		/* Enable i2s */
 		ep93xx_i2s_write_reg(info, EP93XX_I2S_GLCTRL, 1);
@@ -119,6 +131,8 @@ static void ep93xx_i2s_enable(struct ep93xx_i2s_info *info, int stream)
 		ep93xx_i2s_write_reg(info, EP93XX_I2S_TXCTRL,
 				     EP93XX_I2S_TXCTRL_TXEMPTY_LVL |
 				     EP93XX_I2S_TXCTRL_TXUFIE);
+
+	return 0;
 }
 
 static void ep93xx_i2s_disable(struct ep93xx_i2s_info *info, int stream)
@@ -195,9 +209,7 @@ static int ep93xx_i2s_startup(struct snd_pcm_substream *substream,
 {
 	struct ep93xx_i2s_info *info = snd_soc_dai_get_drvdata(dai);
 
-	ep93xx_i2s_enable(info, substream->stream);
-
-	return 0;
+	return ep93xx_i2s_enable(info, substream->stream);
 }
 
 static void ep93xx_i2s_shutdown(struct snd_pcm_substream *substream,
@@ -373,14 +385,16 @@ static int ep93xx_i2s_suspend(struct snd_soc_component *component)
 static int ep93xx_i2s_resume(struct snd_soc_component *component)
 {
 	struct ep93xx_i2s_info *info = snd_soc_component_get_drvdata(component);
+	int err;
 
 	if (!snd_soc_component_active(component))
 		return 0;
 
-	ep93xx_i2s_enable(info, SNDRV_PCM_STREAM_PLAYBACK);
-	ep93xx_i2s_enable(info, SNDRV_PCM_STREAM_CAPTURE);
+	err = ep93xx_i2s_enable(info, SNDRV_PCM_STREAM_PLAYBACK);
+	if (err)
+		return err;
 
-	return 0;
+	return ep93xx_i2s_enable(info, SNDRV_PCM_STREAM_CAPTURE);
 }
 #else
 #define ep93xx_i2s_suspend	NULL
-- 
2.47.3