Re: rsnd_adg_clk_control() sometimes disables already-disabled clock

[Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>]

Hi Geert

Thank you for reporting

>     ------------[ cut here ]------------
>     clk_multiplier already disabled
(snip)
>     ------------[ cut here ]------------
>     clk_multiplier already unprepared
(snip)
> Unfortunately I cannot reproduce it at will.
> The above is from today's renesas-devel release, but my logs indicate
> it happens every few months since at least v6.1.
> So far I have seen it on all Salvator-X(S) variants, but not on any other
> SoCs or boards.

Hmm... I'm not sure why, but according to the log, it seems it calls
clk_disable_unprepare() without calling clk_prepare_enable().
I think "clk_multiplier" means "cs2000" on Salvator-X(S).

Basically, I don't think it can be happen. But current rsnd driver doesn't
check return value of clk_prepare_enable(). So if cs2000 failed clk_enable()
for some reasons, indeed clk_disable_unprepare() might be called without
enabled (It is another issue, though...)

I'm not tesed, but can this patch improve situation ?

If above assumption was correct, the clk WARNING issue itself can be solved,
but sound driver itself will fail to probe...

------------------
From: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Date: Tue, 17 Dec 2024 11:30:46 +0900
Subject: [PATCH] ASoC: rsnd: check rsnd_adg_clk_enable() return value

rsnd_adg_clk_enable() might be failed for some reasons. In such case,
we will get WARNING from clk.c when suspend was used that it try to
disable clk without enabled. Check rsnd_adg_clk_enable() return value.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
---
 sound/soc/renesas/rcar/adg.c  | 30 ++++++++++++++++++++++++------
 sound/soc/renesas/rcar/core.c |  4 +---
 sound/soc/renesas/rcar/rsnd.h |  2 +-
 3 files changed, 26 insertions(+), 10 deletions(-)

diff --git a/sound/soc/renesas/rcar/adg.c b/sound/soc/renesas/rcar/adg.c
index 0f190abf00e75..723dcc88af306 100644
--- a/sound/soc/renesas/rcar/adg.c
+++ b/sound/soc/renesas/rcar/adg.c
@@ -374,12 +374,12 @@ int rsnd_adg_ssi_clk_try_start(struct rsnd_mod *ssi_mod, unsigned int rate)
 	return 0;
 }
 
-void rsnd_adg_clk_control(struct rsnd_priv *priv, int enable)
+int rsnd_adg_clk_control(struct rsnd_priv *priv, int enable)
 {
 	struct rsnd_adg *adg = rsnd_priv_to_adg(priv);
 	struct rsnd_mod *adg_mod = rsnd_mod_get(adg);
 	struct clk *clk;
-	int i;
+	int ret = 0, i;
 
 	if (enable) {
 		rsnd_mod_bset(adg_mod, BRGCKR, 0x80770000, adg->ckr);
@@ -389,18 +389,33 @@ void rsnd_adg_clk_control(struct rsnd_priv *priv, int enable)
 
 	for_each_rsnd_clkin(clk, adg, i) {
 		if (enable) {
-			clk_prepare_enable(clk);
+			ret = clk_prepare_enable(clk);
 
 			/*
 			 * We shouldn't use clk_get_rate() under
 			 * atomic context. Let's keep it when
 			 * rsnd_adg_clk_enable() was called
 			 */
-			adg->clkin_rate[i] = clk_get_rate(clk);
+			if (ret < 0)
+				break;
+			else
+				adg->clkin_rate[i] = clk_get_rate(clk);
 		} else {
-			clk_disable_unprepare(clk);
+			if (adg->clkin_rate[i])
+				clk_disable_unprepare(clk);
+
+			adg->clkin_rate[i] = 0;
 		}
 	}
+
+	/*
+	 * rsnd_adg_clk_enable() might return error (_disable() will not).
+	 * We need to rollback in such case
+	 */
+	if (ret < 0)
+		rsnd_adg_clk_disable(priv);
+
+	return ret;
 }
 
 static struct clk *rsnd_adg_create_null_clk(struct rsnd_priv *priv,
@@ -753,7 +768,10 @@ int rsnd_adg_probe(struct rsnd_priv *priv)
 	if (ret)
 		return ret;
 
-	rsnd_adg_clk_enable(priv);
+	ret = rsnd_adg_clk_enable(priv);
+	if (ret)
+		return ret;
+
 	rsnd_adg_clk_dbg_info(priv, NULL);
 
 	return 0;
diff --git a/sound/soc/renesas/rcar/core.c b/sound/soc/renesas/rcar/core.c
index e2234928c9e88..d3709fd0409e4 100644
--- a/sound/soc/renesas/rcar/core.c
+++ b/sound/soc/renesas/rcar/core.c
@@ -2086,9 +2086,7 @@ static int __maybe_unused rsnd_resume(struct device *dev)
 {
 	struct rsnd_priv *priv = dev_get_drvdata(dev);
 
-	rsnd_adg_clk_enable(priv);
-
-	return 0;
+	return rsnd_adg_clk_enable(priv);
 }
 
 static const struct dev_pm_ops rsnd_pm_ops = {
diff --git a/sound/soc/renesas/rcar/rsnd.h b/sound/soc/renesas/rcar/rsnd.h
index 3c164d8e3b16b..a5f54b65313c4 100644
--- a/sound/soc/renesas/rcar/rsnd.h
+++ b/sound/soc/renesas/rcar/rsnd.h
@@ -608,7 +608,7 @@ int rsnd_adg_set_cmd_timsel_gen2(struct rsnd_mod *cmd_mod,
 				 struct rsnd_dai_stream *io);
 #define rsnd_adg_clk_enable(priv)	rsnd_adg_clk_control(priv, 1)
 #define rsnd_adg_clk_disable(priv)	rsnd_adg_clk_control(priv, 0)
-void rsnd_adg_clk_control(struct rsnd_priv *priv, int enable);
+int rsnd_adg_clk_control(struct rsnd_priv *priv, int enable);
 void rsnd_adg_clk_dbg_info(struct rsnd_priv *priv, struct seq_file *m);
 
 /*
-- 
2.43.0



Thank you for your help !!

Best regards
---
Kuninori Morimoto