[PATCH 3/3] ASoC: renesas: fsi: Fix hang by enabling SPU clock

[phucduc.bui@gmail.com]

From: bui duc phuc <phucduc.bui@gmail.com>

The FSI on r8a7740 requires the SPU clock to be enabled
before accessing its registers.
Without this clock, register access may lead to a system
hang.
Retrieve the "spu" clock in probe and enable it during
DAI startup. Disable the clock on shutdown to match the
audio stream lifecycle.
This ensures safe register access and prevents system
hangs during audio playback.
This is required even if the FSI functional clock is
enabled, as internal units depend on the SPU clock.

Signed-off-by: bui duc phuc <phucduc.bui@gmail.com>
---
 sound/soc/renesas/fsi.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/sound/soc/renesas/fsi.c b/sound/soc/renesas/fsi.c
index 1491c2f2cc96..44bd1c1e6294 100644
--- a/sound/soc/renesas/fsi.c
+++ b/sound/soc/renesas/fsi.c
@@ -292,6 +292,7 @@ struct fsi_master {
 	void __iomem *base;
 	struct fsi_priv fsia;
 	struct fsi_priv fsib;
+	struct clk *clk_spu;
 	const struct fsi_core *core;
 	spinlock_t lock;
 };
@@ -1554,6 +1555,11 @@ static int fsi_dai_startup(struct snd_pcm_substream *substream,
 			   struct snd_soc_dai *dai)
 {
 	struct fsi_priv *fsi = fsi_get_priv(substream);
+	int ret;
+
+	ret = clk_prepare_enable(fsi->master->clk_spu);
+	if (ret)
+		return ret;
 
 	fsi_clk_invalid(fsi);
 
@@ -1566,6 +1572,7 @@ static void fsi_dai_shutdown(struct snd_pcm_substream *substream,
 	struct fsi_priv *fsi = fsi_get_priv(substream);
 
 	fsi_clk_invalid(fsi);
+	clk_disable_unprepare(fsi->master->clk_spu);
 }
 
 static int fsi_dai_trigger(struct snd_pcm_substream *substream, int cmd,
@@ -1963,6 +1970,13 @@ static int fsi_probe(struct platform_device *pdev)
 	master->core		= core;
 	spin_lock_init(&master->lock);
 
+	/* SPU clock is required for FSI register access */
+	master->clk_spu = devm_clk_get(&pdev->dev, "spu");
+	if (IS_ERR(master->clk_spu)) {
+		dev_err(&pdev->dev, "Failed to get spu clock\n");
+		return PTR_ERR(master->clk_spu);
+	}
+
 	/* FSI A setting */
 	fsi		= &master->fsia;
 	fsi->base	= master->base;
-- 
2.43.0