Re: [PATCH v5 2/7] mux: Add helper functions for getting optional and selected mux-state

Re: [PATCH v5 2/7] mux: Add helper functions for getting optional and selected mux-state

[kernel test robot]

BCC: lkp@intel.com
CC: oe-kbuild-all@lists.linux.dev
In-Reply-To: <20260118-rz-sdio-mux-v5-2-3c37e8872683@solid-run.com>
References: <20260118-rz-sdio-mux-v5-2-3c37e8872683@solid-run.com>
TO: Josua Mayer <josua@solid-run.com>
TO: "Marc Kleine-Budde" <mkl@pengutronix.de>
TO: Vincent Mailhol <mailhol@kernel.org>
TO: Vinod Koul <vkoul@kernel.org>
TO: Neil Armstrong <neil.armstrong@linaro.org>
TO: Peter Rosin <peda@axentia.se>
TO: Aaro Koskinen <aaro.koskinen@iki.fi>
TO: Andreas Kemnade <andreas@kemnade.info>
TO: Kevin Hilman <khilman@baylibre.com>
TO: Roger Quadros <rogerq@kernel.org>
TO: Tony Lindgren <tony@atomide.com>
TO: Janusz Krzysztofik <jmkrzyszt@gmail.com>
TO: Vignesh R <vigneshr@ti.com>
TO: Andi Shyti <andi.shyti@kernel.org>
TO: Ulf Hansson <ulf.hansson@linaro.org>
TO: Rob Herring <robh@kernel.org>
TO: Krzysztof Kozlowski <krzk@kernel.org>
TO: Conor Dooley <conor+dt@kernel.org>
TO: Geert Uytterhoeven <geert+renesas@glider.be>
TO: Magnus Damm <magnus.damm@gmail.com>
TO: Wolfram Sang <wsa-dev@sang-engineering.com>
CC: Yazan Shhady <yazan.shhady@solid-run.com>
CC: Jon Nettleton <jon@solid-run.com>
CC: Mikhail Anikin <mikhail.anikin@solid-run.com>
CC: linux-can@vger.kernel.org
CC: linux-phy@lists.infradead.org
CC: linux-kernel@vger.kernel.org
CC: linux-omap@vger.kernel.org
CC: linux-i2c@vger.kernel.org
CC: linux-mmc@vger.kernel.org
CC: devicetree@vger.kernel.org

Hi Josua,

kernel test robot noticed the following build warnings:

[auto build test WARNING on 8f0b4cce4481fb22653697cced8d0d04027cb1e8]

url:    https://github.com/intel-lab-lkp/linux/commits/Josua-Mayer/phy-can-transceiver-rename-temporary-helper-function-to-avoid-conflict/20260118-183905
base:   8f0b4cce4481fb22653697cced8d0d04027cb1e8
patch link:    https://lore.kernel.org/r/20260118-rz-sdio-mux-v5-2-3c37e8872683%40solid-run.com
patch subject: [PATCH v5 2/7] mux: Add helper functions for getting optional and selected mux-state
:::::: branch date: 7 hours ago
:::::: commit date: 7 hours ago
config: i386-randconfig-054-20260118 (https://download.01.org/0day-ci/archive/20260119/202601190136.Fpl1Voph-lkp@intel.com/config)
compiler: gcc-14 (Debian 14.2.0-19) 14.2.0

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Julia Lawall <julia.lawall@inria.fr>
| Closes: https://lore.kernel.org/r/202601190136.Fpl1Voph-lkp@intel.com/

cocci warnings: (new ones prefixed by >>)
>> drivers/mux/core.c:721:18-24: ERROR: reference preceded by free on line 720

vim +721 drivers/mux/core.c

a3b02a9c6591ce drivers/mux/mux-core.c Peter Rosin 2017-05-14  702  
6632866df852bd drivers/mux/core.c     Peter Rosin 2022-01-07  703  /*
6632866df852bd drivers/mux/core.c     Peter Rosin 2022-01-07  704   * mux_state_get() - Get the mux-state for a device.
6632866df852bd drivers/mux/core.c     Peter Rosin 2022-01-07  705   * @dev: The device that needs a mux-state.
6632866df852bd drivers/mux/core.c     Peter Rosin 2022-01-07  706   * @mux_name: The name identifying the mux-state.
6632866df852bd drivers/mux/core.c     Peter Rosin 2022-01-07  707   *
6632866df852bd drivers/mux/core.c     Peter Rosin 2022-01-07  708   * Return: A pointer to the mux-state, or an ERR_PTR with a negative errno.
6632866df852bd drivers/mux/core.c     Peter Rosin 2022-01-07  709   */
f7086d2a8ffae3 drivers/mux/core.c     Josua Mayer 2026-01-18  710  static struct mux_state *mux_state_get(struct device *dev, const char *mux_name, bool optional)
6632866df852bd drivers/mux/core.c     Peter Rosin 2022-01-07  711  {
6632866df852bd drivers/mux/core.c     Peter Rosin 2022-01-07  712  	struct mux_state *mstate;
6632866df852bd drivers/mux/core.c     Peter Rosin 2022-01-07  713  
6632866df852bd drivers/mux/core.c     Peter Rosin 2022-01-07  714  	mstate = kzalloc(sizeof(*mstate), GFP_KERNEL);
6632866df852bd drivers/mux/core.c     Peter Rosin 2022-01-07  715  	if (!mstate)
6632866df852bd drivers/mux/core.c     Peter Rosin 2022-01-07  716  		return ERR_PTR(-ENOMEM);
6632866df852bd drivers/mux/core.c     Peter Rosin 2022-01-07  717  
f7086d2a8ffae3 drivers/mux/core.c     Josua Mayer 2026-01-18  718  	mstate->mux = mux_get(dev, mux_name, &mstate->state, optional);
f7086d2a8ffae3 drivers/mux/core.c     Josua Mayer 2026-01-18  719  	if (IS_ERR_OR_NULL(mstate->mux)) {
6632866df852bd drivers/mux/core.c     Peter Rosin 2022-01-07 @720  		kfree(mstate);
f7086d2a8ffae3 drivers/mux/core.c     Josua Mayer 2026-01-18 @721  		return ERR_CAST(mstate->mux);
6632866df852bd drivers/mux/core.c     Peter Rosin 2022-01-07  722  	}
6632866df852bd drivers/mux/core.c     Peter Rosin 2022-01-07  723  
6632866df852bd drivers/mux/core.c     Peter Rosin 2022-01-07  724  	return mstate;
6632866df852bd drivers/mux/core.c     Peter Rosin 2022-01-07  725  }
6632866df852bd drivers/mux/core.c     Peter Rosin 2022-01-07  726  

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

[PATCH v5 0/7] mmc: host: renesas_sdhi_core: support configuring an optional sdio mux

[Josua Mayer]

Some Renesas SoC based boards mux SD and eMMC on a single sdio
controller, exposing user control by dip switch and software control by
gpio.

Purpose is to simplify development and provisioning by selecting boot
media at power-on, and again before starting linux.

Add binding and driver support for linking a (gpio) mux to renesas sdio
controller.

Introduce generic helper functions for getting managed and selected
mux-state objects, and switch i2c-omap and phy-can-transceiver drivers.

Cc: Yazan Shhady <yazan.shhady@solid-run.com>
Cc: Jon Nettleton <jon@solid-run.com>
Cc: Mikhail Anikin <mikhail.anikin@solid-run.com>
To: Marc Kleine-Budde <mkl@pengutronix.de>
To: Vincent Mailhol <mailhol@kernel.org>
To: Vinod Koul <vkoul@kernel.org>
To: Neil Armstrong <neil.armstrong@linaro.org>
To: Peter Rosin <peda@axentia.se>
To: Aaro Koskinen <aaro.koskinen@iki.fi>
To: Andreas Kemnade <andreas@kemnade.info>
To: Kevin Hilman <khilman@baylibre.com>
To: Roger Quadros <rogerq@kernel.org>
To: Tony Lindgren <tony@atomide.com>
To: Janusz Krzysztofik <jmkrzyszt@gmail.com>
To: Vignesh R <vigneshr@ti.com>
To: Andi Shyti <andi.shyti@kernel.org>
To: Ulf Hansson <ulf.hansson@linaro.org>
To: Rob Herring <robh@kernel.org>
To: Krzysztof Kozlowski <krzk+dt@kernel.org>
To: Conor Dooley <conor+dt@kernel.org>
To: Geert Uytterhoeven <geert+renesas@glider.be>
To: Magnus Damm <magnus.damm@gmail.com>
To: Wolfram Sang <wsa+renesas@sang-engineering.com>
Cc: linux-can@vger.kernel.org
Cc: linux-phy@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-omap@vger.kernel.org
Cc: linux-i2c@vger.kernel.org
Cc: linux-mmc@vger.kernel.org
Cc: devicetree@vger.kernel.org
Cc: linux-renesas-soc@vger.kernel.org
Signed-off-by: Josua Mayer <josua@solid-run.com>

Changes in v5:
- implemented automatic mux deselect for devm_*_selected.
  (Reported-by: Wolfram Sang <wsa+renesas@sang-engineering.com>)
- because of semantic changes I dropped reviewed and acks from omap-i2c
  patch (Andreas Kemnade / Wolfram Sang).
- fix invalid return value in void function for mux helper stubs
  (Reported-by: kernel test robot <lkp@intel.com>)
- Link to v4: https://lore.kernel.org/r/20251229-rz-sdio-mux-v4-0-a023e55758fe@solid-run.com

Changes in v4:
- added MULTIPLEXER Kconfig help text.
- removed "select MULTIPLEXER" from renesas sdhi Kconfig, as it is
  not required for all devices using this driver.
- added stubs for all symbols exported by mux core.
  (Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>)
- refactored mux core logic to silence ENOENT errors only on optional
  code paths, keeping error printing unchanged otherwise.
  (Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>)
- picked up various reviewed- and acked-by tags
- Link to v3: https://lore.kernel.org/r/20251210-rz-sdio-mux-v3-0-ca628db56d60@solid-run.com

Changes in v3:
- updated omap-i2c and phy-can-transceiver to use new helpers.
- created generic helper functions for getting managed optional mux-state.
  (Reported-by: Rob Herring <robh@kernel.org>)
- picked up binding ack by Rob Herring.
- replaced use of "SDIO" with "SD/SDIO/eMMC" in binding document and
  commit descriptions.
  (Reported-by: Ulf Hansson <ulf.hansson@linaro.org>)
- Link to v2: https://lore.kernel.org/r/20251201-rz-sdio-mux-v2-0-bcb581b88dd7@solid-run.com

Changes in v2:
- dropped mux-controller node from dt binding example
  (Reported-by: Conor Dooley <conor@kernel.org>
- Link to v1: https://lore.kernel.org/r/20251128-rz-sdio-mux-v1-0-1ede318d160f@solid-run.com

Reported-by: 
---
Josua Mayer (7):
      phy: can-transceiver: rename temporary helper function to avoid conflict
      mux: Add helper functions for getting optional and selected mux-state
      mux: add help text for MULTIPLEXER config option
      phy: can-transceiver: drop temporary helper getting optional mux-state
      i2c: omap: switch to new generic helper for getting selected mux-state
      dt-bindings: mmc: renesas,sdhi: Add mux-states property
      mmc: host: renesas_sdhi_core: support selecting an optional mux

 .../devicetree/bindings/mmc/renesas,sdhi.yaml      |   6 +
 drivers/i2c/busses/i2c-omap.c                      |  24 +--
 drivers/mmc/host/renesas_sdhi_core.c               |   6 +
 drivers/mux/Kconfig                                |   8 +
 drivers/mux/core.c                                 | 175 +++++++++++++++++----
 drivers/phy/phy-can-transceiver.c                  |  10 --
 include/linux/mux/consumer.h                       | 111 ++++++++++++-
 7 files changed, 278 insertions(+), 62 deletions(-)
---
base-commit: 8f0b4cce4481fb22653697cced8d0d04027cb1e8
change-id: 20251128-rz-sdio-mux-acc5137f1618

Best regards,
-- 
Josua Mayer <josua@solid-run.com>

[PATCH v5 2/7] mux: Add helper functions for getting optional and selected mux-state

[Josua Mayer]

In-tree phy-can-transceiver driver has already implemented a local
version of devm_mux_state_get_optional.

The omap-i2c driver gets and selects an optional mux in its probe
function without using any helper.

Add new helper functions covering both aforementioned use-cases:

- mux_control_get_optional:
  Get a mux-control if specified in dt, return NULL otherwise.
- devm_mux_state_get_optional:
  Get a mux-state if specified in dt, return NULL otherwise.
- devm_mux_state_get_selected:
  Get and select a mux-state specified in dt, return error otherwise.
- devm_mux_state_get_optional_selected:
  Get and select a mux-state if specified in dt, return error or NULL.

Existing mux_get helper function is changed to take an extra argument
indicating whether the mux is optional.
In this case no error is printed, and NULL returned in case of ENOENT.

Calling code is adapted to handle NULL return case, and to pass optional
argument as required.

To support automatic deselect for _selected helper, a new structure is
created storing an exit pointer similar to clock core which is called on
release.

To facilitate code sharing between optional/mandatory/selected helpers,
a new internal helper function is added to handle quiet (optional) and
verbose (mandatory) errors, as well as storing the correct callback for
devm release: __devm_mux_state_get

Due to this structure devm_mux_state_get_*_selected can no longer print
a useful error message when select fails. Instead callers should print
errors where needed.

Commit e153fdea9db04 ("phy: can-transceiver: Re-instate "mux-states"
property presence check") noted that "mux_get() always prints an error
message in case of an error, including when the property is not present,
confusing the user."

The first error message covers the case that a mux name is not matched
in dt. The second error message is based on of_parse_phandle_with_args
return value.

In optional case no error is printed and NULL is returned.
This ensures that the new helper functions will not confuse the user
either.

With the addition of optional helper functions it became clear that
drivers should compile and link even if CONFIG_MULTIPLEXER was not enabled.
Add stubs for all symbols exported by mux core.

Signed-off-by: Josua Mayer <josua@solid-run.com>
---
 drivers/mux/core.c           | 175 ++++++++++++++++++++++++++++++++++++-------
 include/linux/mux/consumer.h | 111 ++++++++++++++++++++++++++-
 2 files changed, 253 insertions(+), 33 deletions(-)

diff --git a/drivers/mux/core.c b/drivers/mux/core.c
index a3840fe0995f..df30f96ec076 100644
--- a/drivers/mux/core.c
+++ b/drivers/mux/core.c
@@ -46,6 +46,16 @@ static const struct class mux_class = {
 	.name = "mux",
 };
 
+/*
+ * struct devm_mux_state_state - 	Tracks managed resources for mux-state objects.
+ * @mux:				Pointer to a mux state.
+ * @exit:				An optional callback to execte before free.
+ */
+struct devm_mux_state_state {
+	struct mux_state *mstate;
+	int (*exit)(struct mux_state *mstate);
+};
+
 static DEFINE_IDA(mux_ida);
 
 static int __init mux_init(void)
@@ -522,11 +532,12 @@ static struct mux_chip *of_find_mux_chip_by_node(struct device_node *np)
  * @mux_name: The name identifying the mux-control.
  * @state: Pointer to where the requested state is returned, or NULL when
  *         the required multiplexer states are handled by other means.
+ * @optional: Whether to return NULL and silence errors when mux doesn't exist.
  *
  * Return: A pointer to the mux-control, or an ERR_PTR with a negative errno.
  */
 static struct mux_control *mux_get(struct device *dev, const char *mux_name,
-				   unsigned int *state)
+				   unsigned int *state, bool optional)
 {
 	struct device_node *np = dev->of_node;
 	struct of_phandle_args args;
@@ -542,7 +553,9 @@ static struct mux_control *mux_get(struct device *dev, const char *mux_name,
 		else
 			index = of_property_match_string(np, "mux-control-names",
 							 mux_name);
-		if (index < 0) {
+		if (index < 0 && optional) {
+			return NULL;
+		} else if (index < 0) {
 			dev_err(dev, "mux controller '%s' not found\n",
 				mux_name);
 			return ERR_PTR(index);
@@ -558,8 +571,12 @@ static struct mux_control *mux_get(struct device *dev, const char *mux_name,
 						 "mux-controls", "#mux-control-cells",
 						 index, &args);
 	if (ret) {
+		if (optional && ret == -ENOENT)
+			return NULL;
+
 		dev_err(dev, "%pOF: failed to get mux-%s %s(%i)\n",
-			np, state ? "state" : "control", mux_name ?: "", index);
+			np, state ? "state" : "control",
+			mux_name ?: "", index);
 		return ERR_PTR(ret);
 	}
 
@@ -617,10 +634,23 @@ static struct mux_control *mux_get(struct device *dev, const char *mux_name,
  */
 struct mux_control *mux_control_get(struct device *dev, const char *mux_name)
 {
-	return mux_get(dev, mux_name, NULL);
+	return mux_get(dev, mux_name, NULL, false);
 }
 EXPORT_SYMBOL_GPL(mux_control_get);
 
+/**
+ * mux_control_get_optional() - Get the optional mux-control for a device.
+ * @dev: The device that needs a mux-control.
+ * @mux_name: The name identifying the mux-control.
+ *
+ * Return: A pointer to the mux-control, an ERR_PTR with a negative errno.
+ */
+struct mux_control *mux_control_get_optional(struct device *dev, const char *mux_name)
+{
+	return mux_get(dev, mux_name, NULL, true);
+}
+EXPORT_SYMBOL_GPL(mux_control_get_optional);
+
 /**
  * mux_control_put() - Put away the mux-control for good.
  * @mux: The mux-control to put away.
@@ -657,8 +687,8 @@ struct mux_control *devm_mux_control_get(struct device *dev,
 	if (!ptr)
 		return ERR_PTR(-ENOMEM);
 
-	mux = mux_control_get(dev, mux_name);
-	if (IS_ERR(mux)) {
+	mux = mux_get(dev, mux_name, NULL, false);
+	if (IS_ERR_OR_NULL(mux)) {
 		devres_free(ptr);
 		return mux;
 	}
@@ -677,7 +707,7 @@ EXPORT_SYMBOL_GPL(devm_mux_control_get);
  *
  * Return: A pointer to the mux-state, or an ERR_PTR with a negative errno.
  */
-static struct mux_state *mux_state_get(struct device *dev, const char *mux_name)
+static struct mux_state *mux_state_get(struct device *dev, const char *mux_name, bool optional)
 {
 	struct mux_state *mstate;
 
@@ -685,12 +715,10 @@ static struct mux_state *mux_state_get(struct device *dev, const char *mux_name)
 	if (!mstate)
 		return ERR_PTR(-ENOMEM);
 
-	mstate->mux = mux_get(dev, mux_name, &mstate->state);
-	if (IS_ERR(mstate->mux)) {
-		int err = PTR_ERR(mstate->mux);
-
+	mstate->mux = mux_get(dev, mux_name, &mstate->state, optional);
+	if (IS_ERR_OR_NULL(mstate->mux)) {
 		kfree(mstate);
-		return ERR_PTR(err);
+		return ERR_CAST(mstate->mux);
 	}
 
 	return mstate;
@@ -710,41 +738,130 @@ static void mux_state_put(struct mux_state *mstate)
 
 static void devm_mux_state_release(struct device *dev, void *res)
 {
-	struct mux_state *mstate = *(struct mux_state **)res;
+	struct devm_mux_state_state *devm_state = res;
 
-	mux_state_put(mstate);
+	if (devm_state->exit)
+		devm_state->exit(devm_state->mstate);
+
+	mux_state_put(devm_state->mstate);
 }
 
 /**
- * devm_mux_state_get() - Get the mux-state for a device, with resource
- *			  management.
- * @dev: The device that needs a mux-control.
- * @mux_name: The name identifying the mux-control.
+ * __devm_mux_state_get() - Get the optional mux-state for a device,
+ *			    with resource management.
+ * @dev: The device that needs a mux-state.
+ * @mux_name: The name identifying the mux-state.
+ * @optional: Whether to return NULL and silence errors when mux doesn't exist.
+ * @init: Optional function pointer for mux-state object initialisation.
+ * @exit: Optional function pointer for mux-state object cleanup on release.
  *
  * Return: Pointer to the mux-state, or an ERR_PTR with a negative errno.
  */
-struct mux_state *devm_mux_state_get(struct device *dev,
-				     const char *mux_name)
+static struct mux_state *__devm_mux_state_get(struct device *dev, const char *mux_name,
+					      bool optional,
+					      int (*init)(struct mux_state *mstate),
+					      int (*exit)(struct mux_state *mstate))
 {
-	struct mux_state **ptr, *mstate;
+	struct devm_mux_state_state *devm_state;
+	struct mux_state *mstate;
+	int ret;
 
-	ptr = devres_alloc(devm_mux_state_release, sizeof(*ptr), GFP_KERNEL);
-	if (!ptr)
+	devm_state = devres_alloc(devm_mux_state_release, sizeof(*devm_state), GFP_KERNEL);
+	if (!devm_state)
 		return ERR_PTR(-ENOMEM);
 
-	mstate = mux_state_get(dev, mux_name);
-	if (IS_ERR(mstate)) {
-		devres_free(ptr);
-		return mstate;
+	mstate = mux_state_get(dev, mux_name, optional);
+	if (IS_ERR_OR_NULL(mstate))
+		goto err_mux_state_get;
+
+	if (init) {
+		ret = init(mstate);
+		if (ret)
+			goto err_mux_state_init;
 	}
 
-	*ptr = mstate;
-	devres_add(dev, ptr);
+	devm_state->mstate = mstate;
+	devm_state->exit = exit;
+	devres_add(dev, devm_state);
 
 	return mstate;
+
+err_mux_state_init:
+	mux_state_put(mstate);
+err_mux_state_get:
+	devres_free(devm_state);
+	return ERR_PTR(ret);
+}
+
+/**
+ * devm_mux_state_get() - Get the mux-state for a device, with resource
+ *			  management.
+ * @dev: The device that needs a mux-control.
+ * @mux_name: The name identifying the mux-control.
+ *
+ * Return: Pointer to the mux-state, or an ERR_PTR with a negative errno.
+ *
+ * The mux-state will automatically be freed on release.
+ */
+struct mux_state *devm_mux_state_get(struct device *dev, const char *mux_name)
+{
+	return __devm_mux_state_get(dev, mux_name, false, NULL, NULL);
 }
 EXPORT_SYMBOL_GPL(devm_mux_state_get);
 
+/**
+ * devm_mux_state_get_optional() - Get the optional mux-state for a device,
+ *				   with resource management.
+ * @dev: The device that needs a mux-state.
+ * @mux_name: The name identifying the mux-state.
+ *
+ * Return: Pointer to the mux-state, or an ERR_PTR with a negative errno.
+ *
+ * The mux-state will automatically be freed on release.
+ */
+struct mux_state *devm_mux_state_get_optional(struct device *dev, const char *mux_name)
+{
+	return __devm_mux_state_get(dev, mux_name, true, NULL, NULL);
+}
+EXPORT_SYMBOL_GPL(devm_mux_state_get_optional);
+
+/**
+ * devm_mux_state_get_selected() - Get the mux-state for a device, with
+ *				   resource management.
+ * @dev: The device that needs a mux-state.
+ * @mux_name: The name identifying the mux-state.
+ *
+ * Return: Pointer to the mux-state, or an ERR_PTR with a negative errno.
+ *
+ * The returned mux-state (if valid) is already selected.
+ *
+ * The mux-state will automatically be deselected and freed on release.
+ */
+struct mux_state *devm_mux_state_get_selected(struct device *dev, const char *mux_name)
+{
+	return __devm_mux_state_get(dev, mux_name, false, mux_state_select, mux_state_deselect);
+}
+EXPORT_SYMBOL_GPL(devm_mux_state_get_selected);
+
+/**
+ * devm_mux_state_get_optional_selected() - Get the optional mux-state for
+ *					    a device, with resource management.
+ * @dev: The device that needs a mux-state.
+ * @mux_name: The name identifying the mux-state.
+ *
+ * Return: Pointer to the mux-state, or an ERR_PTR with a negative errno.
+ *
+ * The returned mux-state (if valid) is already selected.
+ *
+ * The mux-state will automatically be deselected and freed on release.
+ */
+struct mux_state *devm_mux_state_get_optional_selected(struct device *dev,
+						       const char *mux_name)
+{
+	return __devm_mux_state_get(dev, mux_name, true, mux_state_select, mux_state_deselect);
+}
+EXPORT_SYMBOL_GPL(devm_mux_state_get_optional_selected);
+
 /*
  * Using subsys_initcall instead of module_init here to try to ensure - for
  * the non-modular case - that the subsystem is initialized when mux consumers
diff --git a/include/linux/mux/consumer.h b/include/linux/mux/consumer.h
index 2e25c838f831..7d591be26b64 100644
--- a/include/linux/mux/consumer.h
+++ b/include/linux/mux/consumer.h
@@ -16,6 +16,8 @@ struct device;
 struct mux_control;
 struct mux_state;
 
+#ifdef CONFIG_MULTIPLEXER
+
 unsigned int mux_control_states(struct mux_control *mux);
 int __must_check mux_control_select_delay(struct mux_control *mux,
 					  unsigned int state,
@@ -54,11 +56,112 @@ int mux_control_deselect(struct mux_control *mux);
 int mux_state_deselect(struct mux_state *mstate);
 
 struct mux_control *mux_control_get(struct device *dev, const char *mux_name);
+struct mux_control *mux_control_get_optional(struct device *dev, const char *mux_name);
 void mux_control_put(struct mux_control *mux);
 
-struct mux_control *devm_mux_control_get(struct device *dev,
-					 const char *mux_name);
-struct mux_state *devm_mux_state_get(struct device *dev,
-				     const char *mux_name);
+struct mux_control *devm_mux_control_get(struct device *dev, const char *mux_name);
+struct mux_state *devm_mux_state_get(struct device *dev, const char *mux_name);
+struct mux_state *devm_mux_state_get_optional(struct device *dev, const char *mux_name);
+struct mux_state *devm_mux_state_get_selected(struct device *dev, const char *mux_name);
+struct mux_state *devm_mux_state_get_optional_selected(struct device *dev, const char *mux_name);
+
+#else
+
+static inline unsigned int mux_control_states(struct mux_control *mux)
+{
+	return 0;
+}
+static inline int __must_check mux_control_select_delay(struct mux_control *mux,
+							unsigned int state, unsigned int delay_us)
+{
+	return -EOPNOTSUPP;
+}
+static inline int __must_check mux_state_select_delay(struct mux_state *mstate,
+						      unsigned int delay_us)
+{
+	return -EOPNOTSUPP;
+}
+static inline int __must_check mux_control_try_select_delay(struct mux_control *mux,
+							    unsigned int state,
+							    unsigned int delay_us)
+{
+	return -EOPNOTSUPP;
+}
+static inline int __must_check mux_state_try_select_delay(struct mux_state *mstate,
+							  unsigned int delay_us)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int __must_check mux_control_select(struct mux_control *mux,
+						  unsigned int state)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int __must_check mux_state_select(struct mux_state *mstate)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int __must_check mux_control_try_select(struct mux_control *mux,
+						      unsigned int state)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int __must_check mux_state_try_select(struct mux_state *mstate)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int mux_control_deselect(struct mux_control *mux)
+{
+	return -EOPNOTSUPP;
+}
+static inline int mux_state_deselect(struct mux_state *mstate)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline struct mux_control *mux_control_get(struct device *dev, const char *mux_name)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
+static inline struct mux_control *mux_control_get_optional(struct device *dev,
+							   const char *mux_name)
+{
+	return NULL;
+}
+static inline void mux_control_put(struct mux_control *mux)
+{
+	return;
+}
+
+static inline struct mux_control *devm_mux_control_get(struct device *dev, const char *mux_name)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
+static inline struct mux_state *devm_mux_state_get(struct device *dev, const char *mux_name)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
+static inline struct mux_state *devm_mux_state_get_optional(struct device *dev,
+							    const char *mux_name)
+{
+	return NULL;
+}
+static inline struct mux_state *devm_mux_state_get_selected(struct device *dev,
+							    const char *mux_name)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
+static inline struct mux_state *devm_mux_state_get_optional_selected(struct device *dev,
+								     const char *mux_name)
+{
+	return NULL;
+}
+
+#endif /* CONFIG_MULTIPLEXER */
 
 #endif /* _LINUX_MUX_CONSUMER_H */

-- 
2.43.0

[PATCH v5 2/7] mux: Add helper functions for getting optional and selected mux-state

[Josua Mayer]

In-tree phy-can-transceiver driver has already implemented a local
version of devm_mux_state_get_optional.

The omap-i2c driver gets and selects an optional mux in its probe
function without using any helper.

Add new helper functions covering both aforementioned use-cases:

- mux_control_get_optional:
  Get a mux-control if specified in dt, return NULL otherwise.
- devm_mux_state_get_optional:
  Get a mux-state if specified in dt, return NULL otherwise.
- devm_mux_state_get_selected:
  Get and select a mux-state specified in dt, return error otherwise.
- devm_mux_state_get_optional_selected:
  Get and select a mux-state if specified in dt, return error or NULL.

Existing mux_get helper function is changed to take an extra argument
indicating whether the mux is optional.
In this case no error is printed, and NULL returned in case of ENOENT.

Calling code is adapted to handle NULL return case, and to pass optional
argument as required.

To support automatic deselect for _selected helper, a new structure is
created storing an exit pointer similar to clock core which is called on
release.

To facilitate code sharing between optional/mandatory/selected helpers,
a new internal helper function is added to handle quiet (optional) and
verbose (mandatory) errors, as well as storing the correct callback for
devm release: __devm_mux_state_get

Due to this structure devm_mux_state_get_*_selected can no longer print
a useful error message when select fails. Instead callers should print
errors where needed.

Commit e153fdea9db04 ("phy: can-transceiver: Re-instate "mux-states"
property presence check") noted that "mux_get() always prints an error
message in case of an error, including when the property is not present,
confusing the user."

The first error message covers the case that a mux name is not matched
in dt. The second error message is based on of_parse_phandle_with_args
return value.

In optional case no error is printed and NULL is returned.
This ensures that the new helper functions will not confuse the user
either.

With the addition of optional helper functions it became clear that
drivers should compile and link even if CONFIG_MULTIPLEXER was not enabled.
Add stubs for all symbols exported by mux core.

Signed-off-by: Josua Mayer <josua@solid-run.com>
---
 drivers/mux/core.c           | 175 ++++++++++++++++++++++++++++++++++++-------
 include/linux/mux/consumer.h | 111 ++++++++++++++++++++++++++-
 2 files changed, 253 insertions(+), 33 deletions(-)

diff --git a/drivers/mux/core.c b/drivers/mux/core.c
index a3840fe0995f..df30f96ec076 100644
--- a/drivers/mux/core.c
+++ b/drivers/mux/core.c
@@ -46,6 +46,16 @@ static const struct class mux_class = {
 	.name = "mux",
 };
 
+/*
+ * struct devm_mux_state_state - 	Tracks managed resources for mux-state objects.
+ * @mux:				Pointer to a mux state.
+ * @exit:				An optional callback to execte before free.
+ */
+struct devm_mux_state_state {
+	struct mux_state *mstate;
+	int (*exit)(struct mux_state *mstate);
+};
+
 static DEFINE_IDA(mux_ida);
 
 static int __init mux_init(void)
@@ -522,11 +532,12 @@ static struct mux_chip *of_find_mux_chip_by_node(struct device_node *np)
  * @mux_name: The name identifying the mux-control.
  * @state: Pointer to where the requested state is returned, or NULL when
  *         the required multiplexer states are handled by other means.
+ * @optional: Whether to return NULL and silence errors when mux doesn't exist.
  *
  * Return: A pointer to the mux-control, or an ERR_PTR with a negative errno.
  */
 static struct mux_control *mux_get(struct device *dev, const char *mux_name,
-				   unsigned int *state)
+				   unsigned int *state, bool optional)
 {
 	struct device_node *np = dev->of_node;
 	struct of_phandle_args args;
@@ -542,7 +553,9 @@ static struct mux_control *mux_get(struct device *dev, const char *mux_name,
 		else
 			index = of_property_match_string(np, "mux-control-names",
 							 mux_name);
-		if (index < 0) {
+		if (index < 0 && optional) {
+			return NULL;
+		} else if (index < 0) {
 			dev_err(dev, "mux controller '%s' not found\n",
 				mux_name);
 			return ERR_PTR(index);
@@ -558,8 +571,12 @@ static struct mux_control *mux_get(struct device *dev, const char *mux_name,
 						 "mux-controls", "#mux-control-cells",
 						 index, &args);
 	if (ret) {
+		if (optional && ret == -ENOENT)
+			return NULL;
+
 		dev_err(dev, "%pOF: failed to get mux-%s %s(%i)\n",
-			np, state ? "state" : "control", mux_name ?: "", index);
+			np, state ? "state" : "control",
+			mux_name ?: "", index);
 		return ERR_PTR(ret);
 	}
 
@@ -617,10 +634,23 @@ static struct mux_control *mux_get(struct device *dev, const char *mux_name,
  */
 struct mux_control *mux_control_get(struct device *dev, const char *mux_name)
 {
-	return mux_get(dev, mux_name, NULL);
+	return mux_get(dev, mux_name, NULL, false);
 }
 EXPORT_SYMBOL_GPL(mux_control_get);
 
+/**
+ * mux_control_get_optional() - Get the optional mux-control for a device.
+ * @dev: The device that needs a mux-control.
+ * @mux_name: The name identifying the mux-control.
+ *
+ * Return: A pointer to the mux-control, an ERR_PTR with a negative errno.
+ */
+struct mux_control *mux_control_get_optional(struct device *dev, const char *mux_name)
+{
+	return mux_get(dev, mux_name, NULL, true);
+}
+EXPORT_SYMBOL_GPL(mux_control_get_optional);
+
 /**
  * mux_control_put() - Put away the mux-control for good.
  * @mux: The mux-control to put away.
@@ -657,8 +687,8 @@ struct mux_control *devm_mux_control_get(struct device *dev,
 	if (!ptr)
 		return ERR_PTR(-ENOMEM);
 
-	mux = mux_control_get(dev, mux_name);
-	if (IS_ERR(mux)) {
+	mux = mux_get(dev, mux_name, NULL, false);
+	if (IS_ERR_OR_NULL(mux)) {
 		devres_free(ptr);
 		return mux;
 	}
@@ -677,7 +707,7 @@ EXPORT_SYMBOL_GPL(devm_mux_control_get);
  *
  * Return: A pointer to the mux-state, or an ERR_PTR with a negative errno.
  */
-static struct mux_state *mux_state_get(struct device *dev, const char *mux_name)
+static struct mux_state *mux_state_get(struct device *dev, const char *mux_name, bool optional)
 {
 	struct mux_state *mstate;
 
@@ -685,12 +715,10 @@ static struct mux_state *mux_state_get(struct device *dev, const char *mux_name)
 	if (!mstate)
 		return ERR_PTR(-ENOMEM);
 
-	mstate->mux = mux_get(dev, mux_name, &mstate->state);
-	if (IS_ERR(mstate->mux)) {
-		int err = PTR_ERR(mstate->mux);
-
+	mstate->mux = mux_get(dev, mux_name, &mstate->state, optional);
+	if (IS_ERR_OR_NULL(mstate->mux)) {
 		kfree(mstate);
-		return ERR_PTR(err);
+		return ERR_CAST(mstate->mux);
 	}
 
 	return mstate;
@@ -710,41 +738,130 @@ static void mux_state_put(struct mux_state *mstate)
 
 static void devm_mux_state_release(struct device *dev, void *res)
 {
-	struct mux_state *mstate = *(struct mux_state **)res;
+	struct devm_mux_state_state *devm_state = res;
 
-	mux_state_put(mstate);
+	if (devm_state->exit)
+		devm_state->exit(devm_state->mstate);
+
+	mux_state_put(devm_state->mstate);
 }
 
 /**
- * devm_mux_state_get() - Get the mux-state for a device, with resource
- *			  management.
- * @dev: The device that needs a mux-control.
- * @mux_name: The name identifying the mux-control.
+ * __devm_mux_state_get() - Get the optional mux-state for a device,
+ *			    with resource management.
+ * @dev: The device that needs a mux-state.
+ * @mux_name: The name identifying the mux-state.
+ * @optional: Whether to return NULL and silence errors when mux doesn't exist.
+ * @init: Optional function pointer for mux-state object initialisation.
+ * @exit: Optional function pointer for mux-state object cleanup on release.
  *
  * Return: Pointer to the mux-state, or an ERR_PTR with a negative errno.
  */
-struct mux_state *devm_mux_state_get(struct device *dev,
-				     const char *mux_name)
+static struct mux_state *__devm_mux_state_get(struct device *dev, const char *mux_name,
+					      bool optional,
+					      int (*init)(struct mux_state *mstate),
+					      int (*exit)(struct mux_state *mstate))
 {
-	struct mux_state **ptr, *mstate;
+	struct devm_mux_state_state *devm_state;
+	struct mux_state *mstate;
+	int ret;
 
-	ptr = devres_alloc(devm_mux_state_release, sizeof(*ptr), GFP_KERNEL);
-	if (!ptr)
+	devm_state = devres_alloc(devm_mux_state_release, sizeof(*devm_state), GFP_KERNEL);
+	if (!devm_state)
 		return ERR_PTR(-ENOMEM);
 
-	mstate = mux_state_get(dev, mux_name);
-	if (IS_ERR(mstate)) {
-		devres_free(ptr);
-		return mstate;
+	mstate = mux_state_get(dev, mux_name, optional);
+	if (IS_ERR_OR_NULL(mstate))
+		goto err_mux_state_get;
+
+	if (init) {
+		ret = init(mstate);
+		if (ret)
+			goto err_mux_state_init;
 	}
 
-	*ptr = mstate;
-	devres_add(dev, ptr);
+	devm_state->mstate = mstate;
+	devm_state->exit = exit;
+	devres_add(dev, devm_state);
 
 	return mstate;
+
+err_mux_state_init:
+	mux_state_put(mstate);
+err_mux_state_get:
+	devres_free(devm_state);
+	return ERR_PTR(ret);
+}
+
+/**
+ * devm_mux_state_get() - Get the mux-state for a device, with resource
+ *			  management.
+ * @dev: The device that needs a mux-control.
+ * @mux_name: The name identifying the mux-control.
+ *
+ * Return: Pointer to the mux-state, or an ERR_PTR with a negative errno.
+ *
+ * The mux-state will automatically be freed on release.
+ */
+struct mux_state *devm_mux_state_get(struct device *dev, const char *mux_name)
+{
+	return __devm_mux_state_get(dev, mux_name, false, NULL, NULL);
 }
 EXPORT_SYMBOL_GPL(devm_mux_state_get);
 
+/**
+ * devm_mux_state_get_optional() - Get the optional mux-state for a device,
+ *				   with resource management.
+ * @dev: The device that needs a mux-state.
+ * @mux_name: The name identifying the mux-state.
+ *
+ * Return: Pointer to the mux-state, or an ERR_PTR with a negative errno.
+ *
+ * The mux-state will automatically be freed on release.
+ */
+struct mux_state *devm_mux_state_get_optional(struct device *dev, const char *mux_name)
+{
+	return __devm_mux_state_get(dev, mux_name, true, NULL, NULL);
+}
+EXPORT_SYMBOL_GPL(devm_mux_state_get_optional);
+
+/**
+ * devm_mux_state_get_selected() - Get the mux-state for a device, with
+ *				   resource management.
+ * @dev: The device that needs a mux-state.
+ * @mux_name: The name identifying the mux-state.
+ *
+ * Return: Pointer to the mux-state, or an ERR_PTR with a negative errno.
+ *
+ * The returned mux-state (if valid) is already selected.
+ *
+ * The mux-state will automatically be deselected and freed on release.
+ */
+struct mux_state *devm_mux_state_get_selected(struct device *dev, const char *mux_name)
+{
+	return __devm_mux_state_get(dev, mux_name, false, mux_state_select, mux_state_deselect);
+}
+EXPORT_SYMBOL_GPL(devm_mux_state_get_selected);
+
+/**
+ * devm_mux_state_get_optional_selected() - Get the optional mux-state for
+ *					    a device, with resource management.
+ * @dev: The device that needs a mux-state.
+ * @mux_name: The name identifying the mux-state.
+ *
+ * Return: Pointer to the mux-state, or an ERR_PTR with a negative errno.
+ *
+ * The returned mux-state (if valid) is already selected.
+ *
+ * The mux-state will automatically be deselected and freed on release.
+ */
+struct mux_state *devm_mux_state_get_optional_selected(struct device *dev,
+						       const char *mux_name)
+{
+	return __devm_mux_state_get(dev, mux_name, true, mux_state_select, mux_state_deselect);
+}
+EXPORT_SYMBOL_GPL(devm_mux_state_get_optional_selected);
+
 /*
  * Using subsys_initcall instead of module_init here to try to ensure - for
  * the non-modular case - that the subsystem is initialized when mux consumers
diff --git a/include/linux/mux/consumer.h b/include/linux/mux/consumer.h
index 2e25c838f831..7d591be26b64 100644
--- a/include/linux/mux/consumer.h
+++ b/include/linux/mux/consumer.h
@@ -16,6 +16,8 @@ struct device;
 struct mux_control;
 struct mux_state;
 
+#ifdef CONFIG_MULTIPLEXER
+
 unsigned int mux_control_states(struct mux_control *mux);
 int __must_check mux_control_select_delay(struct mux_control *mux,
 					  unsigned int state,
@@ -54,11 +56,112 @@ int mux_control_deselect(struct mux_control *mux);
 int mux_state_deselect(struct mux_state *mstate);
 
 struct mux_control *mux_control_get(struct device *dev, const char *mux_name);
+struct mux_control *mux_control_get_optional(struct device *dev, const char *mux_name);
 void mux_control_put(struct mux_control *mux);
 
-struct mux_control *devm_mux_control_get(struct device *dev,
-					 const char *mux_name);
-struct mux_state *devm_mux_state_get(struct device *dev,
-				     const char *mux_name);
+struct mux_control *devm_mux_control_get(struct device *dev, const char *mux_name);
+struct mux_state *devm_mux_state_get(struct device *dev, const char *mux_name);
+struct mux_state *devm_mux_state_get_optional(struct device *dev, const char *mux_name);
+struct mux_state *devm_mux_state_get_selected(struct device *dev, const char *mux_name);
+struct mux_state *devm_mux_state_get_optional_selected(struct device *dev, const char *mux_name);
+
+#else
+
+static inline unsigned int mux_control_states(struct mux_control *mux)
+{
+	return 0;
+}
+static inline int __must_check mux_control_select_delay(struct mux_control *mux,
+							unsigned int state, unsigned int delay_us)
+{
+	return -EOPNOTSUPP;
+}
+static inline int __must_check mux_state_select_delay(struct mux_state *mstate,
+						      unsigned int delay_us)
+{
+	return -EOPNOTSUPP;
+}
+static inline int __must_check mux_control_try_select_delay(struct mux_control *mux,
+							    unsigned int state,
+							    unsigned int delay_us)
+{
+	return -EOPNOTSUPP;
+}
+static inline int __must_check mux_state_try_select_delay(struct mux_state *mstate,
+							  unsigned int delay_us)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int __must_check mux_control_select(struct mux_control *mux,
+						  unsigned int state)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int __must_check mux_state_select(struct mux_state *mstate)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int __must_check mux_control_try_select(struct mux_control *mux,
+						      unsigned int state)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int __must_check mux_state_try_select(struct mux_state *mstate)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int mux_control_deselect(struct mux_control *mux)
+{
+	return -EOPNOTSUPP;
+}
+static inline int mux_state_deselect(struct mux_state *mstate)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline struct mux_control *mux_control_get(struct device *dev, const char *mux_name)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
+static inline struct mux_control *mux_control_get_optional(struct device *dev,
+							   const char *mux_name)
+{
+	return NULL;
+}
+static inline void mux_control_put(struct mux_control *mux)
+{
+	return;
+}
+
+static inline struct mux_control *devm_mux_control_get(struct device *dev, const char *mux_name)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
+static inline struct mux_state *devm_mux_state_get(struct device *dev, const char *mux_name)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
+static inline struct mux_state *devm_mux_state_get_optional(struct device *dev,
+							    const char *mux_name)
+{
+	return NULL;
+}
+static inline struct mux_state *devm_mux_state_get_selected(struct device *dev,
+							    const char *mux_name)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
+static inline struct mux_state *devm_mux_state_get_optional_selected(struct device *dev,
+								     const char *mux_name)
+{
+	return NULL;
+}
+
+#endif /* CONFIG_MULTIPLEXER */
 
 #endif /* _LINUX_MUX_CONSUMER_H */

-- 
2.43.0



-- 
linux-phy mailing list
linux-phy@lists.infradead.org
https://lists.infradead.org/mailman/listinfo/linux-phy

Re: [PATCH v5 2/7] mux: Add helper functions for getting optional and selected mux-state

[kernel test robot]

Hi Josua,

kernel test robot noticed the following build warnings:

[auto build test WARNING on 8f0b4cce4481fb22653697cced8d0d04027cb1e8]

url:    https://github.com/intel-lab-lkp/linux/commits/Josua-Mayer/phy-can-transceiver-rename-temporary-helper-function-to-avoid-conflict/20260118-183905
base:   8f0b4cce4481fb22653697cced8d0d04027cb1e8
patch link:    https://lore.kernel.org/r/20260118-rz-sdio-mux-v5-2-3c37e8872683%40solid-run.com
patch subject: [PATCH v5 2/7] mux: Add helper functions for getting optional and selected mux-state
config: um-randconfig-r071-20260118 (https://download.01.org/0day-ci/archive/20260118/202601182117.l2nFZ5OB-lkp@intel.com/config)
compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project 9b8addffa70cee5b2acc5454712d9cf78ce45710)
smatch version: v0.5.0-8985-g2614ff1a
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260118/202601182117.l2nFZ5OB-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202601182117.l2nFZ5OB-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/mux/core.c:774:6: warning: variable 'ret' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
     774 |         if (IS_ERR_OR_NULL(mstate))
         |             ^~~~~~~~~~~~~~~~~~~~~~
   drivers/mux/core.c:793:17: note: uninitialized use occurs here
     793 |         return ERR_PTR(ret);
         |                        ^~~
   drivers/mux/core.c:774:2: note: remove the 'if' if its condition is always false
     774 |         if (IS_ERR_OR_NULL(mstate))
         |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~
     775 |                 goto err_mux_state_get;
         |                 ~~~~~~~~~~~~~~~~~~~~~~
   drivers/mux/core.c:767:9: note: initialize the variable 'ret' to silence this warning
     767 |         int ret;
         |                ^
         |                 = 0
   1 warning generated.


vim +774 drivers/mux/core.c

   748	
   749	/**
   750	 * __devm_mux_state_get() - Get the optional mux-state for a device,
   751	 *			    with resource management.
   752	 * @dev: The device that needs a mux-state.
   753	 * @mux_name: The name identifying the mux-state.
   754	 * @optional: Whether to return NULL and silence errors when mux doesn't exist.
   755	 * @init: Optional function pointer for mux-state object initialisation.
   756	 * @exit: Optional function pointer for mux-state object cleanup on release.
   757	 *
   758	 * Return: Pointer to the mux-state, or an ERR_PTR with a negative errno.
   759	 */
   760	static struct mux_state *__devm_mux_state_get(struct device *dev, const char *mux_name,
   761						      bool optional,
   762						      int (*init)(struct mux_state *mstate),
   763						      int (*exit)(struct mux_state *mstate))
   764	{
   765		struct devm_mux_state_state *devm_state;
   766		struct mux_state *mstate;
   767		int ret;
   768	
   769		devm_state = devres_alloc(devm_mux_state_release, sizeof(*devm_state), GFP_KERNEL);
   770		if (!devm_state)
   771			return ERR_PTR(-ENOMEM);
   772	
   773		mstate = mux_state_get(dev, mux_name, optional);
 > 774		if (IS_ERR_OR_NULL(mstate))
   775			goto err_mux_state_get;
   776	
   777		if (init) {
   778			ret = init(mstate);
   779			if (ret)
   780				goto err_mux_state_init;
   781		}
   782	
   783		devm_state->mstate = mstate;
   784		devm_state->exit = exit;
   785		devres_add(dev, devm_state);
   786	
   787		return mstate;
   788	
   789	err_mux_state_init:
   790		mux_state_put(mstate);
   791	err_mux_state_get:
   792		devres_free(devm_state);
   793		return ERR_PTR(ret);
   794	}
   795	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH v5 2/7] mux: Add helper functions for getting optional and selected mux-state

[kernel test robot]

Hi Josua,

kernel test robot noticed the following build warnings:

[auto build test WARNING on 8f0b4cce4481fb22653697cced8d0d04027cb1e8]

url:    https://github.com/intel-lab-lkp/linux/commits/Josua-Mayer/phy-can-transceiver-rename-temporary-helper-function-to-avoid-conflict/20260118-183905
base:   8f0b4cce4481fb22653697cced8d0d04027cb1e8
patch link:    https://lore.kernel.org/r/20260118-rz-sdio-mux-v5-2-3c37e8872683%40solid-run.com
patch subject: [PATCH v5 2/7] mux: Add helper functions for getting optional and selected mux-state
config: um-randconfig-r071-20260118 (https://download.01.org/0day-ci/archive/20260118/202601182117.l2nFZ5OB-lkp@intel.com/config)
compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project 9b8addffa70cee5b2acc5454712d9cf78ce45710)
smatch version: v0.5.0-8985-g2614ff1a
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260118/202601182117.l2nFZ5OB-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202601182117.l2nFZ5OB-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/mux/core.c:774:6: warning: variable 'ret' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
     774 |         if (IS_ERR_OR_NULL(mstate))
         |             ^~~~~~~~~~~~~~~~~~~~~~
   drivers/mux/core.c:793:17: note: uninitialized use occurs here
     793 |         return ERR_PTR(ret);
         |                        ^~~
   drivers/mux/core.c:774:2: note: remove the 'if' if its condition is always false
     774 |         if (IS_ERR_OR_NULL(mstate))
         |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~
     775 |                 goto err_mux_state_get;
         |                 ~~~~~~~~~~~~~~~~~~~~~~
   drivers/mux/core.c:767:9: note: initialize the variable 'ret' to silence this warning
     767 |         int ret;
         |                ^
         |                 = 0
   1 warning generated.


vim +774 drivers/mux/core.c

   748	
   749	/**
   750	 * __devm_mux_state_get() - Get the optional mux-state for a device,
   751	 *			    with resource management.
   752	 * @dev: The device that needs a mux-state.
   753	 * @mux_name: The name identifying the mux-state.
   754	 * @optional: Whether to return NULL and silence errors when mux doesn't exist.
   755	 * @init: Optional function pointer for mux-state object initialisation.
   756	 * @exit: Optional function pointer for mux-state object cleanup on release.
   757	 *
   758	 * Return: Pointer to the mux-state, or an ERR_PTR with a negative errno.
   759	 */
   760	static struct mux_state *__devm_mux_state_get(struct device *dev, const char *mux_name,
   761						      bool optional,
   762						      int (*init)(struct mux_state *mstate),
   763						      int (*exit)(struct mux_state *mstate))
   764	{
   765		struct devm_mux_state_state *devm_state;
   766		struct mux_state *mstate;
   767		int ret;
   768	
   769		devm_state = devres_alloc(devm_mux_state_release, sizeof(*devm_state), GFP_KERNEL);
   770		if (!devm_state)
   771			return ERR_PTR(-ENOMEM);
   772	
   773		mstate = mux_state_get(dev, mux_name, optional);
 > 774		if (IS_ERR_OR_NULL(mstate))
   775			goto err_mux_state_get;
   776	
   777		if (init) {
   778			ret = init(mstate);
   779			if (ret)
   780				goto err_mux_state_init;
   781		}
   782	
   783		devm_state->mstate = mstate;
   784		devm_state->exit = exit;
   785		devres_add(dev, devm_state);
   786	
   787		return mstate;
   788	
   789	err_mux_state_init:
   790		mux_state_put(mstate);
   791	err_mux_state_get:
   792		devres_free(devm_state);
   793		return ERR_PTR(ret);
   794	}
   795	

-- 
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Re: [PATCH v5 2/7] mux: Add helper functions for getting optional and selected mux-state

[Geert Uytterhoeven]

Hi Josua,

On Sun, 18 Jan 2026 at 11:29, Josua Mayer <josua@solid-run.com> wrote:
> In-tree phy-can-transceiver driver has already implemented a local
> version of devm_mux_state_get_optional.
>
> The omap-i2c driver gets and selects an optional mux in its probe
> function without using any helper.
>
> Add new helper functions covering both aforementioned use-cases:
>
> - mux_control_get_optional:
>   Get a mux-control if specified in dt, return NULL otherwise.
> - devm_mux_state_get_optional:
>   Get a mux-state if specified in dt, return NULL otherwise.
> - devm_mux_state_get_selected:
>   Get and select a mux-state specified in dt, return error otherwise.
> - devm_mux_state_get_optional_selected:
>   Get and select a mux-state if specified in dt, return error or NULL.
>
> Existing mux_get helper function is changed to take an extra argument
> indicating whether the mux is optional.
> In this case no error is printed, and NULL returned in case of ENOENT.
>
> Calling code is adapted to handle NULL return case, and to pass optional
> argument as required.
>
> To support automatic deselect for _selected helper, a new structure is
> created storing an exit pointer similar to clock core which is called on
> release.
>
> To facilitate code sharing between optional/mandatory/selected helpers,
> a new internal helper function is added to handle quiet (optional) and
> verbose (mandatory) errors, as well as storing the correct callback for
> devm release: __devm_mux_state_get
>
> Due to this structure devm_mux_state_get_*_selected can no longer print
> a useful error message when select fails. Instead callers should print
> errors where needed.
>
> Commit e153fdea9db04 ("phy: can-transceiver: Re-instate "mux-states"
> property presence check") noted that "mux_get() always prints an error
> message in case of an error, including when the property is not present,
> confusing the user."
>
> The first error message covers the case that a mux name is not matched
> in dt. The second error message is based on of_parse_phandle_with_args
> return value.
>
> In optional case no error is printed and NULL is returned.
> This ensures that the new helper functions will not confuse the user
> either.
>
> With the addition of optional helper functions it became clear that
> drivers should compile and link even if CONFIG_MULTIPLEXER was not enabled.
> Add stubs for all symbols exported by mux core.
>
> Signed-off-by: Josua Mayer <josua@solid-run.com>

Thanks for your patch!

> --- a/drivers/mux/core.c
> +++ b/drivers/mux/core.c

> @@ -677,7 +707,7 @@ EXPORT_SYMBOL_GPL(devm_mux_control_get);
>   *
>   * Return: A pointer to the mux-state, or an ERR_PTR with a negative errno.
>   */
> -static struct mux_state *mux_state_get(struct device *dev, const char *mux_name)
> +static struct mux_state *mux_state_get(struct device *dev, const char *mux_name, bool optional)
>  {
>         struct mux_state *mstate;
>
> @@ -685,12 +715,10 @@ static struct mux_state *mux_state_get(struct device *dev, const char *mux_name)
>         if (!mstate)
>                 return ERR_PTR(-ENOMEM);
>
> -       mstate->mux = mux_get(dev, mux_name, &mstate->state);
> -       if (IS_ERR(mstate->mux)) {
> -               int err = PTR_ERR(mstate->mux);
> -
> +       mstate->mux = mux_get(dev, mux_name, &mstate->state, optional);
> +       if (IS_ERR_OR_NULL(mstate->mux)) {
>                 kfree(mstate);

mstate is freed here...

> -               return ERR_PTR(err);
> +               return ERR_CAST(mstate->mux);

... and dereferenced here, leading to a use after free.

>         }
>
>         return mstate;

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH v5 2/7] mux: Add helper functions for getting optional and selected mux-state

[Geert Uytterhoeven]

Hi Josua,

On Sun, 18 Jan 2026 at 11:29, Josua Mayer <josua@solid-run.com> wrote:
> In-tree phy-can-transceiver driver has already implemented a local
> version of devm_mux_state_get_optional.
>
> The omap-i2c driver gets and selects an optional mux in its probe
> function without using any helper.
>
> Add new helper functions covering both aforementioned use-cases:
>
> - mux_control_get_optional:
>   Get a mux-control if specified in dt, return NULL otherwise.
> - devm_mux_state_get_optional:
>   Get a mux-state if specified in dt, return NULL otherwise.
> - devm_mux_state_get_selected:
>   Get and select a mux-state specified in dt, return error otherwise.
> - devm_mux_state_get_optional_selected:
>   Get and select a mux-state if specified in dt, return error or NULL.
>
> Existing mux_get helper function is changed to take an extra argument
> indicating whether the mux is optional.
> In this case no error is printed, and NULL returned in case of ENOENT.
>
> Calling code is adapted to handle NULL return case, and to pass optional
> argument as required.
>
> To support automatic deselect for _selected helper, a new structure is
> created storing an exit pointer similar to clock core which is called on
> release.
>
> To facilitate code sharing between optional/mandatory/selected helpers,
> a new internal helper function is added to handle quiet (optional) and
> verbose (mandatory) errors, as well as storing the correct callback for
> devm release: __devm_mux_state_get
>
> Due to this structure devm_mux_state_get_*_selected can no longer print
> a useful error message when select fails. Instead callers should print
> errors where needed.
>
> Commit e153fdea9db04 ("phy: can-transceiver: Re-instate "mux-states"
> property presence check") noted that "mux_get() always prints an error
> message in case of an error, including when the property is not present,
> confusing the user."
>
> The first error message covers the case that a mux name is not matched
> in dt. The second error message is based on of_parse_phandle_with_args
> return value.
>
> In optional case no error is printed and NULL is returned.
> This ensures that the new helper functions will not confuse the user
> either.
>
> With the addition of optional helper functions it became clear that
> drivers should compile and link even if CONFIG_MULTIPLEXER was not enabled.
> Add stubs for all symbols exported by mux core.
>
> Signed-off-by: Josua Mayer <josua@solid-run.com>

Thanks for your patch!

> --- a/drivers/mux/core.c
> +++ b/drivers/mux/core.c

> @@ -677,7 +707,7 @@ EXPORT_SYMBOL_GPL(devm_mux_control_get);
>   *
>   * Return: A pointer to the mux-state, or an ERR_PTR with a negative errno.
>   */
> -static struct mux_state *mux_state_get(struct device *dev, const char *mux_name)
> +static struct mux_state *mux_state_get(struct device *dev, const char *mux_name, bool optional)
>  {
>         struct mux_state *mstate;
>
> @@ -685,12 +715,10 @@ static struct mux_state *mux_state_get(struct device *dev, const char *mux_name)
>         if (!mstate)
>                 return ERR_PTR(-ENOMEM);
>
> -       mstate->mux = mux_get(dev, mux_name, &mstate->state);
> -       if (IS_ERR(mstate->mux)) {
> -               int err = PTR_ERR(mstate->mux);
> -
> +       mstate->mux = mux_get(dev, mux_name, &mstate->state, optional);
> +       if (IS_ERR_OR_NULL(mstate->mux)) {
>                 kfree(mstate);

mstate is freed here...

> -               return ERR_PTR(err);
> +               return ERR_CAST(mstate->mux);

... and dereferenced here, leading to a use after free.

>         }
>
>         return mstate;

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

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Re: [PATCH v5 2/7] mux: Add helper functions for getting optional and selected mux-state

[Josua Mayer]

On 20/01/2026 11:45, Geert Uytterhoeven wrote:
> Hi Josua,
>
> On Sun, 18 Jan 2026 at 11:29, Josua Mayer <josua@solid-run.com> wrote:
>> In-tree phy-can-transceiver driver has already implemented a local
>> version of devm_mux_state_get_optional.
>>
>> The omap-i2c driver gets and selects an optional mux in its probe
>> function without using any helper.
>>
>> Add new helper functions covering both aforementioned use-cases:
>>
>> - mux_control_get_optional:
>>    Get a mux-control if specified in dt, return NULL otherwise.
>> - devm_mux_state_get_optional:
>>    Get a mux-state if specified in dt, return NULL otherwise.
>> - devm_mux_state_get_selected:
>>    Get and select a mux-state specified in dt, return error otherwise.
>> - devm_mux_state_get_optional_selected:
>>    Get and select a mux-state if specified in dt, return error or NULL.
>>
>> Existing mux_get helper function is changed to take an extra argument
>> indicating whether the mux is optional.
>> In this case no error is printed, and NULL returned in case of ENOENT.
>>
>> Calling code is adapted to handle NULL return case, and to pass optional
>> argument as required.
>>
>> To support automatic deselect for _selected helper, a new structure is
>> created storing an exit pointer similar to clock core which is called on
>> release.
>>
>> To facilitate code sharing between optional/mandatory/selected helpers,
>> a new internal helper function is added to handle quiet (optional) and
>> verbose (mandatory) errors, as well as storing the correct callback for
>> devm release: __devm_mux_state_get
>>
>> Due to this structure devm_mux_state_get_*_selected can no longer print
>> a useful error message when select fails. Instead callers should print
>> errors where needed.
>>
>> Commit e153fdea9db04 ("phy: can-transceiver: Re-instate "mux-states"
>> property presence check") noted that "mux_get() always prints an error
>> message in case of an error, including when the property is not present,
>> confusing the user."
>>
>> The first error message covers the case that a mux name is not matched
>> in dt. The second error message is based on of_parse_phandle_with_args
>> return value.
>>
>> In optional case no error is printed and NULL is returned.
>> This ensures that the new helper functions will not confuse the user
>> either.
>>
>> With the addition of optional helper functions it became clear that
>> drivers should compile and link even if CONFIG_MULTIPLEXER was not enabled.
>> Add stubs for all symbols exported by mux core.
>>
>> Signed-off-by: Josua Mayer <josua@solid-run.com>
> Thanks for your patch!
>
>> --- a/drivers/mux/core.c
>> +++ b/drivers/mux/core.c
>> @@ -677,7 +707,7 @@ EXPORT_SYMBOL_GPL(devm_mux_control_get);
>>    *
>>    * Return: A pointer to the mux-state, or an ERR_PTR with a negative errno.
>>    */
>> -static struct mux_state *mux_state_get(struct device *dev, const char *mux_name)
>> +static struct mux_state *mux_state_get(struct device *dev, const char *mux_name, bool optional)
>>   {
>>          struct mux_state *mstate;
>>
>> @@ -685,12 +715,10 @@ static struct mux_state *mux_state_get(struct device *dev, const char *mux_name)
>>          if (!mstate)
>>                  return ERR_PTR(-ENOMEM);
>>
>> -       mstate->mux = mux_get(dev, mux_name, &mstate->state);
>> -       if (IS_ERR(mstate->mux)) {
>> -               int err = PTR_ERR(mstate->mux);
>> -
>> +       mstate->mux = mux_get(dev, mux_name, &mstate->state, optional);
>> +       if (IS_ERR_OR_NULL(mstate->mux)) {
>>                  kfree(mstate);
> mstate is freed here...
>
>> -               return ERR_PTR(err);
>> +               return ERR_CAST(mstate->mux);
> ... and dereferenced here, leading to a use after free.
Thank you for spotting this, I will resolve it in next version!

(along with what the kernel robot found)

>
>>          }
>>
>>          return mstate;
> Gr{oetje,eeting}s,
>
>                          Geert
>

Re: [PATCH v5 2/7] mux: Add helper functions for getting optional and selected mux-state

[Josua Mayer]

On 20/01/2026 11:45, Geert Uytterhoeven wrote:
> Hi Josua,
>
> On Sun, 18 Jan 2026 at 11:29, Josua Mayer <josua@solid-run.com> wrote:
>> In-tree phy-can-transceiver driver has already implemented a local
>> version of devm_mux_state_get_optional.
>>
>> The omap-i2c driver gets and selects an optional mux in its probe
>> function without using any helper.
>>
>> Add new helper functions covering both aforementioned use-cases:
>>
>> - mux_control_get_optional:
>>    Get a mux-control if specified in dt, return NULL otherwise.
>> - devm_mux_state_get_optional:
>>    Get a mux-state if specified in dt, return NULL otherwise.
>> - devm_mux_state_get_selected:
>>    Get and select a mux-state specified in dt, return error otherwise.
>> - devm_mux_state_get_optional_selected:
>>    Get and select a mux-state if specified in dt, return error or NULL.
>>
>> Existing mux_get helper function is changed to take an extra argument
>> indicating whether the mux is optional.
>> In this case no error is printed, and NULL returned in case of ENOENT.
>>
>> Calling code is adapted to handle NULL return case, and to pass optional
>> argument as required.
>>
>> To support automatic deselect for _selected helper, a new structure is
>> created storing an exit pointer similar to clock core which is called on
>> release.
>>
>> To facilitate code sharing between optional/mandatory/selected helpers,
>> a new internal helper function is added to handle quiet (optional) and
>> verbose (mandatory) errors, as well as storing the correct callback for
>> devm release: __devm_mux_state_get
>>
>> Due to this structure devm_mux_state_get_*_selected can no longer print
>> a useful error message when select fails. Instead callers should print
>> errors where needed.
>>
>> Commit e153fdea9db04 ("phy: can-transceiver: Re-instate "mux-states"
>> property presence check") noted that "mux_get() always prints an error
>> message in case of an error, including when the property is not present,
>> confusing the user."
>>
>> The first error message covers the case that a mux name is not matched
>> in dt. The second error message is based on of_parse_phandle_with_args
>> return value.
>>
>> In optional case no error is printed and NULL is returned.
>> This ensures that the new helper functions will not confuse the user
>> either.
>>
>> With the addition of optional helper functions it became clear that
>> drivers should compile and link even if CONFIG_MULTIPLEXER was not enabled.
>> Add stubs for all symbols exported by mux core.
>>
>> Signed-off-by: Josua Mayer <josua@solid-run.com>
> Thanks for your patch!
>
>> --- a/drivers/mux/core.c
>> +++ b/drivers/mux/core.c
>> @@ -677,7 +707,7 @@ EXPORT_SYMBOL_GPL(devm_mux_control_get);
>>    *
>>    * Return: A pointer to the mux-state, or an ERR_PTR with a negative errno.
>>    */
>> -static struct mux_state *mux_state_get(struct device *dev, const char *mux_name)
>> +static struct mux_state *mux_state_get(struct device *dev, const char *mux_name, bool optional)
>>   {
>>          struct mux_state *mstate;
>>
>> @@ -685,12 +715,10 @@ static struct mux_state *mux_state_get(struct device *dev, const char *mux_name)
>>          if (!mstate)
>>                  return ERR_PTR(-ENOMEM);
>>
>> -       mstate->mux = mux_get(dev, mux_name, &mstate->state);
>> -       if (IS_ERR(mstate->mux)) {
>> -               int err = PTR_ERR(mstate->mux);
>> -
>> +       mstate->mux = mux_get(dev, mux_name, &mstate->state, optional);
>> +       if (IS_ERR_OR_NULL(mstate->mux)) {
>>                  kfree(mstate);
> mstate is freed here...
>
>> -               return ERR_PTR(err);
>> +               return ERR_CAST(mstate->mux);
> ... and dereferenced here, leading to a use after free.
Thank you for spotting this, I will resolve it in next version!

(along with what the kernel robot found)

>
>>          }
>>
>>          return mstate;
> Gr{oetje,eeting}s,
>
>                          Geert
>

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Re: [PATCH v5 2/7] mux: Add helper functions for getting optional and selected mux-state

[Geert Uytterhoeven]

Hi Josua,

On Sun, 18 Jan 2026 at 11:29, Josua Mayer <josua@solid-run.com> wrote:
> In-tree phy-can-transceiver driver has already implemented a local
> version of devm_mux_state_get_optional.
>
> The omap-i2c driver gets and selects an optional mux in its probe
> function without using any helper.
>
> Add new helper functions covering both aforementioned use-cases:
>
> - mux_control_get_optional:
>   Get a mux-control if specified in dt, return NULL otherwise.
> - devm_mux_state_get_optional:
>   Get a mux-state if specified in dt, return NULL otherwise.
> - devm_mux_state_get_selected:
>   Get and select a mux-state specified in dt, return error otherwise.
> - devm_mux_state_get_optional_selected:
>   Get and select a mux-state if specified in dt, return error or NULL.
>
> Existing mux_get helper function is changed to take an extra argument
> indicating whether the mux is optional.
> In this case no error is printed, and NULL returned in case of ENOENT.
>
> Calling code is adapted to handle NULL return case, and to pass optional
> argument as required.
>
> To support automatic deselect for _selected helper, a new structure is
> created storing an exit pointer similar to clock core which is called on
> release.
>
> To facilitate code sharing between optional/mandatory/selected helpers,
> a new internal helper function is added to handle quiet (optional) and
> verbose (mandatory) errors, as well as storing the correct callback for
> devm release: __devm_mux_state_get
>
> Due to this structure devm_mux_state_get_*_selected can no longer print
> a useful error message when select fails. Instead callers should print
> errors where needed.
>
> Commit e153fdea9db04 ("phy: can-transceiver: Re-instate "mux-states"
> property presence check") noted that "mux_get() always prints an error
> message in case of an error, including when the property is not present,
> confusing the user."
>
> The first error message covers the case that a mux name is not matched
> in dt. The second error message is based on of_parse_phandle_with_args
> return value.
>
> In optional case no error is printed and NULL is returned.
> This ensures that the new helper functions will not confuse the user
> either.
>
> With the addition of optional helper functions it became clear that
> drivers should compile and link even if CONFIG_MULTIPLEXER was not enabled.
> Add stubs for all symbols exported by mux core.
>
> Signed-off-by: Josua Mayer <josua@solid-run.com>

Thanks for your patch!

> --- a/drivers/mux/core.c
> +++ b/drivers/mux/core.c
> @@ -46,6 +46,16 @@ static const struct class mux_class = {
>         .name = "mux",
>  };
>
> +/*
> + * struct devm_mux_state_state -       Tracks managed resources for mux-state objects.

Please run scripts/checkpatch.pl:

    WARNING: please, no space before tabs
    #80: FILE: drivers/mux/core.c:50:
    + * struct devm_mux_state_state - ^ITracks managed resources for
mux-state objects.$

> + * @mux:                               Pointer to a mux state.
> + * @exit:                              An optional callback to execte before free.
> + */
> +struct devm_mux_state_state {
> +       struct mux_state *mstate;
> +       int (*exit)(struct mux_state *mstate);
> +};
> +
>  static DEFINE_IDA(mux_ida);
>
>  static int __init mux_init(void)

> --- a/include/linux/mux/consumer.h
> +++ b/include/linux/mux/consumer.h

> +static inline void mux_control_put(struct mux_control *mux)
> +{
> +       return;
> +}

    WARNING: void function return statements are not generally useful
    #441: FILE: include/linux/mux/consumer.h:139:
    + return;

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH v5 2/7] mux: Add helper functions for getting optional and selected mux-state

[Geert Uytterhoeven]

Hi Josua,

On Sun, 18 Jan 2026 at 11:29, Josua Mayer <josua@solid-run.com> wrote:
> In-tree phy-can-transceiver driver has already implemented a local
> version of devm_mux_state_get_optional.
>
> The omap-i2c driver gets and selects an optional mux in its probe
> function without using any helper.
>
> Add new helper functions covering both aforementioned use-cases:
>
> - mux_control_get_optional:
>   Get a mux-control if specified in dt, return NULL otherwise.
> - devm_mux_state_get_optional:
>   Get a mux-state if specified in dt, return NULL otherwise.
> - devm_mux_state_get_selected:
>   Get and select a mux-state specified in dt, return error otherwise.
> - devm_mux_state_get_optional_selected:
>   Get and select a mux-state if specified in dt, return error or NULL.
>
> Existing mux_get helper function is changed to take an extra argument
> indicating whether the mux is optional.
> In this case no error is printed, and NULL returned in case of ENOENT.
>
> Calling code is adapted to handle NULL return case, and to pass optional
> argument as required.
>
> To support automatic deselect for _selected helper, a new structure is
> created storing an exit pointer similar to clock core which is called on
> release.
>
> To facilitate code sharing between optional/mandatory/selected helpers,
> a new internal helper function is added to handle quiet (optional) and
> verbose (mandatory) errors, as well as storing the correct callback for
> devm release: __devm_mux_state_get
>
> Due to this structure devm_mux_state_get_*_selected can no longer print
> a useful error message when select fails. Instead callers should print
> errors where needed.
>
> Commit e153fdea9db04 ("phy: can-transceiver: Re-instate "mux-states"
> property presence check") noted that "mux_get() always prints an error
> message in case of an error, including when the property is not present,
> confusing the user."
>
> The first error message covers the case that a mux name is not matched
> in dt. The second error message is based on of_parse_phandle_with_args
> return value.
>
> In optional case no error is printed and NULL is returned.
> This ensures that the new helper functions will not confuse the user
> either.
>
> With the addition of optional helper functions it became clear that
> drivers should compile and link even if CONFIG_MULTIPLEXER was not enabled.
> Add stubs for all symbols exported by mux core.
>
> Signed-off-by: Josua Mayer <josua@solid-run.com>

Thanks for your patch!

> --- a/drivers/mux/core.c
> +++ b/drivers/mux/core.c
> @@ -46,6 +46,16 @@ static const struct class mux_class = {
>         .name = "mux",
>  };
>
> +/*
> + * struct devm_mux_state_state -       Tracks managed resources for mux-state objects.

Please run scripts/checkpatch.pl:

    WARNING: please, no space before tabs
    #80: FILE: drivers/mux/core.c:50:
    + * struct devm_mux_state_state - ^ITracks managed resources for
mux-state objects.$

> + * @mux:                               Pointer to a mux state.
> + * @exit:                              An optional callback to execte before free.
> + */
> +struct devm_mux_state_state {
> +       struct mux_state *mstate;
> +       int (*exit)(struct mux_state *mstate);
> +};
> +
>  static DEFINE_IDA(mux_ida);
>
>  static int __init mux_init(void)

> --- a/include/linux/mux/consumer.h
> +++ b/include/linux/mux/consumer.h

> +static inline void mux_control_put(struct mux_control *mux)
> +{
> +       return;
> +}

    WARNING: void function return statements are not generally useful
    #441: FILE: include/linux/mux/consumer.h:139:
    + return;

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

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