[PATCH] i2c: mux: demux-pinctrl: Release pinctrl handles on deactivation

[Wentao Liang <vulab@iscas.ac.cn>]

Each master activation calls devm_pinctrl_get() against the parent I2C
controller device. Switching or removing the demux only releases the
adapter reference, so the pinctrl reference and its devres entry persist
until the parent controller is removed. Repeated switches accumulate
these entries. Activation failures after obtaining the handle retain it
too.

Use pinctrl_get() and keep the handle with the active channel. Release
it when activation fails or the channel is deactivated, before dropping
the parent adapter reference and reverting the device-tree changeset.
Keep the no-pinctrl case working by storing NULL when get returns
-ENODEV.

Fixes: 50a5ba876908 ("i2c: mux: demux-pinctrl: add driver")
Cc: stable@vger.kernel.org
Assisted-by: DeepSeek-V4.1-Flash and OpenAI Codex
Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
---
 drivers/i2c/muxes/i2c-demux-pinctrl.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/i2c/muxes/i2c-demux-pinctrl.c b/drivers/i2c/muxes/i2c-demux-pinctrl.c
index 2403c0bf7c43..1d61a0c6e1f2 100644
--- a/drivers/i2c/muxes/i2c-demux-pinctrl.c
+++ b/drivers/i2c/muxes/i2c-demux-pinctrl.c
@@ -22,6 +22,7 @@
 struct i2c_demux_pinctrl_chan {
 	struct device_node *parent_np;
 	struct i2c_adapter *parent_adap;
+	struct pinctrl *pinctrl;
 	struct of_changeset chgset;
 };
 
@@ -69,12 +70,13 @@ static int i2c_demux_activate_master(struct i2c_demux_pinctrl_priv *priv, u32 ne
 
 	/*
 	 * Check if there are pinctrl states at all. Note: we can't use
-	 * devm_pinctrl_get_select() because we need to distinguish between
-	 * the -ENODEV from devm_pinctrl_get() and pinctrl_lookup_state().
+	 * pinctrl_get_select() because we need to distinguish between
+	 * the -ENODEV from pinctrl_get() and pinctrl_lookup_state().
 	 */
-	p = devm_pinctrl_get(adap->dev.parent);
+	p = pinctrl_get(adap->dev.parent);
 	if (IS_ERR(p)) {
 		ret = PTR_ERR(p);
+		p = NULL;
 		/* continue if just no pinctrl states (e.g. i2c-gpio), otherwise exit */
 		if (ret != -ENODEV)
 			goto err_with_put;
@@ -92,6 +94,7 @@ static int i2c_demux_activate_master(struct i2c_demux_pinctrl_priv *priv, u32 ne
 	}
 
 	priv->chan[new_chan].parent_adap = adap;
+	priv->chan[new_chan].pinctrl = p;
 	priv->cur_chan = new_chan;
 
 	/* Now fill out current adapter structure. cur_chan must be up to date */
@@ -118,6 +121,9 @@ static int i2c_demux_activate_master(struct i2c_demux_pinctrl_priv *priv, u32 ne
 	return 0;
 
  err_with_put:
+	if (p)
+		pinctrl_put(p);
+	priv->chan[new_chan].pinctrl = NULL;
 	i2c_put_adapter(adap);
  err_with_revert:
 	of_changeset_revert(&priv->chan[new_chan].chgset);
@@ -135,6 +141,10 @@ static int i2c_demux_deactivate_master(struct i2c_demux_pinctrl_priv *priv)
 		return 0;
 
 	i2c_del_adapter(&priv->cur_adap);
+	if (priv->chan[cur].pinctrl) {
+		pinctrl_put(priv->chan[cur].pinctrl);
+		priv->chan[cur].pinctrl = NULL;
+	}
 	i2c_put_adapter(priv->chan[cur].parent_adap);
 
 	ret = of_changeset_revert(&priv->chan[cur].chgset);
-- 
2.34.1