[PATCH v3 0/6] mmc: host: renesas_sdhi_core: support configuring an optional sdio mux

[PATCH v3 0/6] 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.

Signed-off-by: Josua Mayer <josua@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>
   Reported-by: Krzysztof Kozlowski <krzk@kernel.org>)
- Link to v1: https://lore.kernel.org/r/20251128-rz-sdio-mux-v1-0-1ede318d160f@solid-run.com

---
Josua Mayer (6):
      phy: can-transceiver: rename temporary helper function to avoid conflict
      mux: Add helper functions for getting optional and selected mux-state
      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                      | 19 ++----
 drivers/mmc/host/Kconfig                           |  1 +
 drivers/mmc/host/renesas_sdhi.h                    |  1 +
 drivers/mmc/host/renesas_sdhi_core.c               | 16 +++++-
 drivers/mux/core.c                                 | 67 +++++++++++++++++++---
 drivers/phy/phy-can-transceiver.c                  | 10 ----
 include/linux/mux/consumer.h                       |  4 ++
 8 files changed, 89 insertions(+), 35 deletions(-)
---
base-commit: 3a8660878839faadb4f1a6dd72c3179c1df56787
change-id: 20251128-rz-sdio-mux-acc5137f1618

Best regards,
-- 
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[PATCH v3 1/6] phy: can-transceiver: rename temporary helper function to avoid conflict

[Josua Mayer]

Rename the temporary devm_mux_state_get_optional function to avoid
conflict with upcoming implementation in multiplexer subsystem.

Signed-off-by: Josua Mayer <josua@solid-run.com>
---
 drivers/phy/phy-can-transceiver.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/phy/phy-can-transceiver.c b/drivers/phy/phy-can-transceiver.c
index f59caff4b3d4c..c02d99f0f29fc 100644
--- a/drivers/phy/phy-can-transceiver.c
+++ b/drivers/phy/phy-can-transceiver.c
@@ -95,7 +95,7 @@ MODULE_DEVICE_TABLE(of, can_transceiver_phy_ids);
 
 /* Temporary wrapper until the multiplexer subsystem supports optional muxes */
 static inline struct mux_state *
-devm_mux_state_get_optional(struct device *dev, const char *mux_name)
+temp_devm_mux_state_get_optional(struct device *dev, const char *mux_name)
 {
 	if (!of_property_present(dev->of_node, "mux-states"))
 		return NULL;
@@ -124,7 +124,7 @@ static int can_transceiver_phy_probe(struct platform_device *pdev)
 	match = of_match_node(can_transceiver_phy_ids, pdev->dev.of_node);
 	drvdata = match->data;
 
-	mux_state = devm_mux_state_get_optional(dev, NULL);
+	mux_state = temp_devm_mux_state_get_optional(dev, NULL);
 	if (IS_ERR(mux_state))
 		return PTR_ERR(mux_state);
 

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[PATCH v3 2/6] 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:

- devm_mux_state_get_optional:
  Get a mux-state if specified in dt, return NULL 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 return -ENOENT in case dt
did not specify a mux-state or -control matching given name (if valid).
This matches of_parse_phandle_with_args semantics which also returns
-ENOENT if the property does nto exists, or its value is zero.

The new helper functions check for ENOENT to return NULL for optional
muxes.

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. This is removed as the returned error code (-ENOENT) is clear.

The second error message is based on of_parse_phandle_with_args return
value. In case mux description is missing from DT, it returns -ENOENT.
Print error message only for other error codes.

This ensures that the new helper functions will not confuse the user
either.

Signed-off-by: Josua Mayer <josua@solid-run.com>
---
 drivers/mux/core.c           | 67 +++++++++++++++++++++++++++++++++++++++-----
 include/linux/mux/consumer.h |  4 +++
 2 files changed, 64 insertions(+), 7 deletions(-)

diff --git a/drivers/mux/core.c b/drivers/mux/core.c
index a3840fe0995fe..130ca47a8be37 100644
--- a/drivers/mux/core.c
+++ b/drivers/mux/core.c
@@ -542,11 +542,8 @@ 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) {
-			dev_err(dev, "mux controller '%s' not found\n",
-				mux_name);
-			return ERR_PTR(index);
-		}
+		if (index < 0)
+			return ERR_PTR(-ENOENT);
 	}
 
 	if (state)
@@ -558,8 +555,10 @@ static struct mux_control *mux_get(struct device *dev, const char *mux_name,
 						 "mux-controls", "#mux-control-cells",
 						 index, &args);
 	if (ret) {
-		dev_err(dev, "%pOF: failed to get mux-%s %s(%i)\n",
-			np, state ? "state" : "control", mux_name ?: "", index);
+		if (ret != -ENOENT)
+			dev_err(dev, "%pOF: failed to get mux-%s %s(%i)\n",
+				np, state ? "state" : "control",
+				mux_name ?: "", index);
 		return ERR_PTR(ret);
 	}
 
@@ -745,6 +744,60 @@ struct mux_state *devm_mux_state_get(struct device *dev,
 }
 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.
+ */
+struct mux_state *devm_mux_state_get_optional(struct device *dev,
+					      const char *mux_name)
+{
+	struct mux_state *mux_state = devm_mux_state_get(dev, mux_name);
+
+	if (IS_ERR(mux_state) && PTR_ERR(mux_state) == -ENOENT)
+		return NULL;
+
+	return mux_state;
+}
+EXPORT_SYMBOL_GPL(devm_mux_state_get_optional);
+
+/**
+ * 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.
+ */
+struct mux_state *devm_mux_state_get_optional_selected(struct device *dev,
+						       const char *mux_name)
+{
+	struct mux_state *mux_state;
+	int ret;
+
+	mux_state = devm_mux_state_get_optional(dev, mux_name);
+	if (IS_ERR_OR_NULL(mux_state))
+		return mux_state;
+
+	ret = mux_state_select(mux_state);
+	if (ret) {
+		if (ret != -EPROBE_DEFER)
+			dev_err(dev, "failed to select mux-state %s: %d\n",
+				mux_name ?: "", ret);
+
+		mux_state_put(mux_state);
+		return ERR_PTR(ret);
+	}
+
+	return mux_state;
+}
+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 2e25c838f8312..a5da2e33a45c0 100644
--- a/include/linux/mux/consumer.h
+++ b/include/linux/mux/consumer.h
@@ -60,5 +60,9 @@ 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_optional_selected(struct device *dev,
+						       const char *mux_name);
 
 #endif /* _LINUX_MUX_CONSUMER_H */

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[PATCH v3 3/6] phy: can-transceiver: drop temporary helper getting optional mux-state

[Josua Mayer]

Multiplexer subsystem has now added helpers for getting managed optional
mux-state.

Switch to the new devm_mux_state_get_optional helper.

This change is only compile-tested.

Signed-off-by: Josua Mayer <josua@solid-run.com>
---
 drivers/phy/phy-can-transceiver.c | 12 +-----------
 1 file changed, 1 insertion(+), 11 deletions(-)

diff --git a/drivers/phy/phy-can-transceiver.c b/drivers/phy/phy-can-transceiver.c
index c02d99f0f29fc..68d72d8d49251 100644
--- a/drivers/phy/phy-can-transceiver.c
+++ b/drivers/phy/phy-can-transceiver.c
@@ -93,16 +93,6 @@ static const struct of_device_id can_transceiver_phy_ids[] = {
 };
 MODULE_DEVICE_TABLE(of, can_transceiver_phy_ids);
 
-/* Temporary wrapper until the multiplexer subsystem supports optional muxes */
-static inline struct mux_state *
-temp_devm_mux_state_get_optional(struct device *dev, const char *mux_name)
-{
-	if (!of_property_present(dev->of_node, "mux-states"))
-		return NULL;
-
-	return devm_mux_state_get(dev, mux_name);
-}
-
 static int can_transceiver_phy_probe(struct platform_device *pdev)
 {
 	struct phy_provider *phy_provider;
@@ -124,7 +114,7 @@ static int can_transceiver_phy_probe(struct platform_device *pdev)
 	match = of_match_node(can_transceiver_phy_ids, pdev->dev.of_node);
 	drvdata = match->data;
 
-	mux_state = temp_devm_mux_state_get_optional(dev, NULL);
+	mux_state = devm_mux_state_get_optional(dev, NULL);
 	if (IS_ERR(mux_state))
 		return PTR_ERR(mux_state);
 

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[PATCH v3 4/6] i2c: omap: switch to new generic helper for getting selected mux-state

[Josua Mayer]

Multiplexer subsystem has added generic helper functiosn for getting an
already selected mux-state object.

Replace existing logic in probe with the equivalent helper function.

This change is only compile-tested.

Signed-off-by: Josua Mayer <josua@solid-run.com>
---
 drivers/i2c/busses/i2c-omap.c | 19 ++++---------------
 1 file changed, 4 insertions(+), 15 deletions(-)

diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
index 5fcc9f6c33e5b..89802027a3eac 100644
--- a/drivers/i2c/busses/i2c-omap.c
+++ b/drivers/i2c/busses/i2c-omap.c
@@ -1454,21 +1454,10 @@ omap_i2c_probe(struct platform_device *pdev)
 				       (1000 * omap->speed / 8);
 	}
 
-	if (of_property_present(node, "mux-states")) {
-		struct mux_state *mux_state;
-
-		mux_state = devm_mux_state_get(&pdev->dev, NULL);
-		if (IS_ERR(mux_state)) {
-			r = PTR_ERR(mux_state);
-			dev_dbg(&pdev->dev, "failed to get I2C mux: %d\n", r);
-			goto err_put_pm;
-		}
-		omap->mux_state = mux_state;
-		r = mux_state_select(omap->mux_state);
-		if (r) {
-			dev_err(&pdev->dev, "failed to select I2C mux: %d\n", r);
-			goto err_put_pm;
-		}
+	omap->mux_state = devm_mux_state_get_optional_selected(&pdev->dev, NULL);
+	if (IS_ERR(omap->mux_state)) {
+		r = PTR_ERR(omap->mux_state);
+		goto err_put_pm;
 	}
 
 	/* reset ASAP, clearing any IRQs */

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[PATCH v3 5/6] dt-bindings: mmc: renesas,sdhi: Add mux-states property

[Josua Mayer]

Add mux controller support for data or control lines that are muxed
between a host and multiple cards.

There are several devices supporting a choice of eMMC or SD on a single
board by both dip switch and gpio, e.g. Renesas RZ/G2L SMARC SoM and
SolidRun RZ/G2L SoM.

In-tree dts for the Renesas boards currently rely on preprocessor macros
and gpio hogs to describe the respective cards.

By adding mux-states property to sdhi controller description, boards can
correctly describe the mux that already exists in hardware - and drivers
can coordinate between mux selection and probing for cards.

Acked-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Josua Mayer <josua@solid-run.com>
---
 Documentation/devicetree/bindings/mmc/renesas,sdhi.yaml | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/devicetree/bindings/mmc/renesas,sdhi.yaml b/Documentation/devicetree/bindings/mmc/renesas,sdhi.yaml
index c754ea71f51f7..64fac0d11329a 100644
--- a/Documentation/devicetree/bindings/mmc/renesas,sdhi.yaml
+++ b/Documentation/devicetree/bindings/mmc/renesas,sdhi.yaml
@@ -106,6 +106,11 @@ properties:
   iommus:
     maxItems: 1
 
+  mux-states:
+    description:
+      mux controller node to route the SD/SDIO/eMMC signals from SoC to cards.
+    maxItems: 1
+
   power-domains:
     maxItems: 1
 
@@ -275,6 +280,7 @@ examples:
         max-frequency = <195000000>;
         power-domains = <&sysc R8A7790_PD_ALWAYS_ON>;
         resets = <&cpg 314>;
+        mux-states = <&mux 0>;
     };
 
     sdhi1: mmc@ee120000 {

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[PATCH v3 6/6] mmc: host: renesas_sdhi_core: support selecting an optional mux

[Josua Mayer]

Some hardware designs route data or control signals through a mux to
support multiple devices on a single sdhi controller.

In particular SolidRun RZ/G2L/G2LC/V2L System on Module use a mux for
switching between soldered eMMC and an optional microSD on a carrier
board, e.g. for development or provisioning.

SD/SDIO/eMMC are not well suited for runtime switching between different
cards, however boot-time selection is possible and useful - in
particular considering dt overlays.

Add support for an optional SD/SDIO/eMMC mux defined in dt, and select
it during probe.

Similar functionality already exists in other places, e.g. i2c-omap.

Signed-off-by: Josua Mayer <josua@solid-run.com>
---
 drivers/mmc/host/Kconfig             |  1 +
 drivers/mmc/host/renesas_sdhi.h      |  1 +
 drivers/mmc/host/renesas_sdhi_core.c | 16 +++++++++++++---
 3 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/drivers/mmc/host/Kconfig b/drivers/mmc/host/Kconfig
index 2c963cb6724b9..c01ab7d81a5af 100644
--- a/drivers/mmc/host/Kconfig
+++ b/drivers/mmc/host/Kconfig
@@ -707,6 +707,7 @@ config MMC_SDHI
 	depends on SUPERH || ARCH_RENESAS || COMPILE_TEST
 	depends on (RESET_CONTROLLER && REGULATOR) || !OF
 	select MMC_TMIO_CORE
+	select MULTIPLEXER
 	help
 	  This provides support for the SDHI SD/SDIO controller found in
 	  Renesas SuperH, ARM and ARM64 based SoCs
diff --git a/drivers/mmc/host/renesas_sdhi.h b/drivers/mmc/host/renesas_sdhi.h
index 084964cecf9d8..9508908d8179f 100644
--- a/drivers/mmc/host/renesas_sdhi.h
+++ b/drivers/mmc/host/renesas_sdhi.h
@@ -97,6 +97,7 @@ struct renesas_sdhi {
 	struct reset_control *rstc;
 	struct tmio_mmc_host *host;
 	struct regulator_dev *rdev;
+	struct mux_state *mux_state;
 };
 
 #define host_to_priv(host) \
diff --git a/drivers/mmc/host/renesas_sdhi_core.c b/drivers/mmc/host/renesas_sdhi_core.c
index f56fa2cd208dd..3d833a325c61f 100644
--- a/drivers/mmc/host/renesas_sdhi_core.c
+++ b/drivers/mmc/host/renesas_sdhi_core.c
@@ -26,6 +26,7 @@
 #include <linux/mmc/mmc.h>
 #include <linux/mmc/slot-gpio.h>
 #include <linux/module.h>
+#include <linux/mux/consumer.h>
 #include <linux/pinctrl/consumer.h>
 #include <linux/pinctrl/pinctrl-state.h>
 #include <linux/platform_data/tmio.h>
@@ -1115,9 +1116,15 @@ int renesas_sdhi_probe(struct platform_device *pdev,
 						"state_uhs");
 	}
 
+	priv->mux_state = devm_mux_state_get_optional_selected(&pdev->dev, NULL);
+	if (IS_ERR(priv->mux_state))
+		return PTR_ERR(priv->mux_state);
+
 	host = tmio_mmc_host_alloc(pdev, mmc_data);
-	if (IS_ERR(host))
-		return PTR_ERR(host);
+	if (IS_ERR(host)) {
+		ret = PTR_ERR(host);
+		goto edselmux;
+	}
 
 	priv->host = host;
 
@@ -1200,7 +1207,7 @@ int renesas_sdhi_probe(struct platform_device *pdev,
 
 	ret = renesas_sdhi_clk_enable(host);
 	if (ret)
-		return ret;
+		goto edselmux;
 
 	rcfg.of_node = of_get_available_child_by_name(dev->of_node, "vqmmc-regulator");
 	if (rcfg.of_node) {
@@ -1304,6 +1311,9 @@ int renesas_sdhi_probe(struct platform_device *pdev,
 
 edisclk:
 	renesas_sdhi_clk_disable(host);
+edselmux:
+	if (priv->mux_state)
+		mux_state_deselect(priv->mux_state);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(renesas_sdhi_probe);

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Re: [PATCH v3 2/6] mux: Add helper functions for getting optional and selected mux-state

[Ulf Hansson]

On Wed, 10 Dec 2025 at 18:39, 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:
>
> - devm_mux_state_get_optional:
>   Get a mux-state if specified in dt, return NULL 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 return -ENOENT in case dt
> did not specify a mux-state or -control matching given name (if valid).
> This matches of_parse_phandle_with_args semantics which also returns
> -ENOENT if the property does nto exists, or its value is zero.
>
> The new helper functions check for ENOENT to return NULL for optional
> muxes.
>
> 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. This is removed as the returned error code (-ENOENT) is clear.
>
> The second error message is based on of_parse_phandle_with_args return
> value. In case mux description is missing from DT, it returns -ENOENT.
> Print error message only for other error codes.
>
> This ensures that the new helper functions will not confuse the user
> either.
>
> Signed-off-by: Josua Mayer <josua@solid-run.com>
> ---
>  drivers/mux/core.c           | 67 +++++++++++++++++++++++++++++++++++++++-----
>  include/linux/mux/consumer.h |  4 +++
>  2 files changed, 64 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/mux/core.c b/drivers/mux/core.c
> index a3840fe0995fe..130ca47a8be37 100644
> --- a/drivers/mux/core.c
> +++ b/drivers/mux/core.c
> @@ -542,11 +542,8 @@ 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) {
> -                       dev_err(dev, "mux controller '%s' not found\n",
> -                               mux_name);
> -                       return ERR_PTR(index);
> -               }
> +               if (index < 0)
> +                       return ERR_PTR(-ENOENT);
>         }
>
>         if (state)
> @@ -558,8 +555,10 @@ static struct mux_control *mux_get(struct device *dev, const char *mux_name,
>                                                  "mux-controls", "#mux-control-cells",
>                                                  index, &args);
>         if (ret) {
> -               dev_err(dev, "%pOF: failed to get mux-%s %s(%i)\n",
> -                       np, state ? "state" : "control", mux_name ?: "", index);
> +               if (ret != -ENOENT)
> +                       dev_err(dev, "%pOF: failed to get mux-%s %s(%i)\n",
> +                               np, state ? "state" : "control",
> +                               mux_name ?: "", index);
>                 return ERR_PTR(ret);
>         }
>
> @@ -745,6 +744,60 @@ struct mux_state *devm_mux_state_get(struct device *dev,
>  }
>  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.
> + */
> +struct mux_state *devm_mux_state_get_optional(struct device *dev,
> +                                             const char *mux_name)
> +{
> +       struct mux_state *mux_state = devm_mux_state_get(dev, mux_name);
> +
> +       if (IS_ERR(mux_state) && PTR_ERR(mux_state) == -ENOENT)
> +               return NULL;
> +
> +       return mux_state;
> +}
> +EXPORT_SYMBOL_GPL(devm_mux_state_get_optional);
> +
> +/**
> + * 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.
> + */
> +struct mux_state *devm_mux_state_get_optional_selected(struct device *dev,
> +                                                      const char *mux_name)
> +{
> +       struct mux_state *mux_state;
> +       int ret;
> +
> +       mux_state = devm_mux_state_get_optional(dev, mux_name);
> +       if (IS_ERR_OR_NULL(mux_state))
> +               return mux_state;
> +
> +       ret = mux_state_select(mux_state);
> +       if (ret) {
> +               if (ret != -EPROBE_DEFER)
> +                       dev_err(dev, "failed to select mux-state %s: %d\n",
> +                               mux_name ?: "", ret);
> +
> +               mux_state_put(mux_state);
> +               return ERR_PTR(ret);
> +       }
> +
> +       return mux_state;
> +}
> +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 2e25c838f8312..a5da2e33a45c0 100644
> --- a/include/linux/mux/consumer.h
> +++ b/include/linux/mux/consumer.h
> @@ -60,5 +60,9 @@ 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_optional_selected(struct device *dev,
> +                                                      const char *mux_name);

Seems like we need stub-functions of these too. Otherwise
subsystems/drivers need to have a "depends on MULTIPLEXER" in their
Kconfigs.

Kind regards
Uffe

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Re: [PATCH v3 0/6] mmc: host: renesas_sdhi_core: support configuring an optional sdio mux

[Ulf Hansson]

On Wed, 10 Dec 2025 at 18:39, Josua Mayer <josua@solid-run.com> wrote:
>
> 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.
>
> Signed-off-by: Josua Mayer <josua@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>
>    Reported-by: Krzysztof Kozlowski <krzk@kernel.org>)
> - Link to v1: https://lore.kernel.org/r/20251128-rz-sdio-mux-v1-0-1ede318d160f@solid-run.com
>
> ---
> Josua Mayer (6):
>       phy: can-transceiver: rename temporary helper function to avoid conflict
>       mux: Add helper functions for getting optional and selected mux-state
>       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                      | 19 ++----
>  drivers/mmc/host/Kconfig                           |  1 +
>  drivers/mmc/host/renesas_sdhi.h                    |  1 +
>  drivers/mmc/host/renesas_sdhi_core.c               | 16 +++++-
>  drivers/mux/core.c                                 | 67 +++++++++++++++++++---
>  drivers/phy/phy-can-transceiver.c                  | 10 ----
>  include/linux/mux/consumer.h                       |  4 ++
>  8 files changed, 89 insertions(+), 35 deletions(-)
> ---
> base-commit: 3a8660878839faadb4f1a6dd72c3179c1df56787
> change-id: 20251128-rz-sdio-mux-acc5137f1618
>
> Best regards,
> --
> Josua Mayer <josua@solid-run.com>

Looks like this needs to go together or if someone can host the common
parts via an immutable branch.

Anyway, I am expecting some discussion or update for patch2 first.

Kind regards
Uffe

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Re: [PATCH v3 2/6] mux: Add helper functions for getting optional and selected mux-state

[Josua Mayer]

Hi Ulf,

Am 17.12.25 um 14:38 schrieb Ulf Hansson:
> On Wed, 10 Dec 2025 at 18:39, Josua Mayer <josua@solid-run.com> wrote:

cut

>>  /*
>>   * 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 2e25c838f8312..a5da2e33a45c0 100644
>> --- a/include/linux/mux/consumer.h
>> +++ b/include/linux/mux/consumer.h
>> @@ -60,5 +60,9 @@ 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_optional_selected(struct device *dev,
>> +                                                      const char *mux_name);
> Seems like we need stub-functions of these too. Otherwise
> subsystems/drivers need to have a "depends on MULTIPLEXER" in their
> Kconfigs.

Currently the drivers that can use a mux select MULTIPLEXER in Kconfig.

There already exist a few mux helpers both for mux-state and for mux-control,
and they might all need stubs.

I'd prefer the restructuring of kconfig dependencies being independent from
adding mux-state functionality to renesas sdhi driver.

sincerely
Josua Mayer
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Re: [PATCH v3 0/6] mmc: host: renesas_sdhi_core: support configuring an optional sdio mux

[Josua Mayer]

Am 17.12.25 um 14:42 schrieb Ulf Hansson:
> On Wed, 10 Dec 2025 at 18:39, Josua Mayer <josua@solid-run.com> wrote:
>> 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.
>>
>> Signed-off-by: Josua Mayer <josua@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>
>>    Reported-by: Krzysztof Kozlowski <krzk@kernel.org>)
>> - Link to v1: https://lore.kernel.org/r/20251128-rz-sdio-mux-v1-0-1ede318d160f@solid-run.com
>>
>> ---
>> Josua Mayer (6):
>>       phy: can-transceiver: rename temporary helper function to avoid conflict
>>       mux: Add helper functions for getting optional and selected mux-state
>>       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                      | 19 ++----
>>  drivers/mmc/host/Kconfig                           |  1 +
>>  drivers/mmc/host/renesas_sdhi.h                    |  1 +
>>  drivers/mmc/host/renesas_sdhi_core.c               | 16 +++++-
>>  drivers/mux/core.c                                 | 67 +++++++++++++++++++---
>>  drivers/phy/phy-can-transceiver.c                  | 10 ----
>>  include/linux/mux/consumer.h                       |  4 ++
>>  8 files changed, 89 insertions(+), 35 deletions(-)
>> ---
>> base-commit: 3a8660878839faadb4f1a6dd72c3179c1df56787
>> change-id: 20251128-rz-sdio-mux-acc5137f1618
>>
>> Best regards,
>> --
>> Josua Mayer <josua@solid-run.com>
> Looks like this needs to go together or if someone can host the common
> parts via an immutable branch.
Yes. Patch 1 is critical and must be applied before 2. Patches 3-5 require 2.
>
> Anyway, I am expecting some discussion or update for patch2 first.
>
> Kind regards
> Uffe
>
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Re: [PATCH v3 2/6] mux: Add helper functions for getting optional and selected mux-state

[Geert Uytterhoeven]

Hi Josua,

On Wed, 10 Dec 2025 at 18:39, 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:
>
> - devm_mux_state_get_optional:
>   Get a mux-state if specified in dt, return NULL 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 return -ENOENT in case dt
> did not specify a mux-state or -control matching given name (if valid).
> This matches of_parse_phandle_with_args semantics which also returns
> -ENOENT if the property does nto exists, or its value is zero.
>
> The new helper functions check for ENOENT to return NULL for optional
> muxes.
>
> 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. This is removed as the returned error code (-ENOENT) is clear.
>
> The second error message is based on of_parse_phandle_with_args return
> value. In case mux description is missing from DT, it returns -ENOENT.
> Print error message only for other error codes.
>
> This ensures that the new helper functions will not confuse the user
> either.
>
> Signed-off-by: Josua Mayer <josua@solid-run.com>

Thanks for your patch!

> --- a/drivers/mux/core.c
> +++ b/drivers/mux/core.c
> @@ -542,11 +542,8 @@ 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) {
> -                       dev_err(dev, "mux controller '%s' not found\n",
> -                               mux_name);
> -                       return ERR_PTR(index);
> -               }
> +               if (index < 0)
> +                       return ERR_PTR(-ENOENT);
>         }
>
>         if (state)
> @@ -558,8 +555,10 @@ static struct mux_control *mux_get(struct device *dev, const char *mux_name,
>                                                  "mux-controls", "#mux-control-cells",
>                                                  index, &args);
>         if (ret) {
> -               dev_err(dev, "%pOF: failed to get mux-%s %s(%i)\n",
> -                       np, state ? "state" : "control", mux_name ?: "", index);
> +               if (ret != -ENOENT)

I think the non-optional variant should still print an error message in
case of -ENOENT, else this has to be duplicated in all drivers using it.

This is typically handled by having a non-printing core helper function,
and having printing non-optional, and non-printing/ignoring optional wrappers
around the former.

> +                       dev_err(dev, "%pOF: failed to get mux-%s %s(%i)\n",
> +                               np, state ? "state" : "control",
> +                               mux_name ?: "", index);
>                 return ERR_PTR(ret);
>         }
>

Gr{oetje,eeting}s,

                        Geert

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Re: [PATCH v3 1/6] phy: can-transceiver: rename temporary helper function to avoid conflict

[Geert Uytterhoeven]

On Wed, 10 Dec 2025 at 18:39, Josua Mayer <josua@solid-run.com> wrote:
> Rename the temporary devm_mux_state_get_optional function to avoid
> conflict with upcoming implementation in multiplexer subsystem.
>
> Signed-off-by: Josua Mayer <josua@solid-run.com>

Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>

Gr{oetje,eeting}s,

                        Geert

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Re: [PATCH v3 3/6] phy: can-transceiver: drop temporary helper getting optional mux-state

[Geert Uytterhoeven]

On Wed, 10 Dec 2025 at 18:39, Josua Mayer <josua@solid-run.com> wrote:
> Multiplexer subsystem has now added helpers for getting managed optional
> mux-state.
>
> Switch to the new devm_mux_state_get_optional helper.
>
> This change is only compile-tested.
>
> Signed-off-by: Josua Mayer <josua@solid-run.com>

Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>

Gr{oetje,eeting}s,

                        Geert

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Re: [PATCH v3 2/6] mux: Add helper functions for getting optional and selected mux-state

[Ulf Hansson]

On Sun, 21 Dec 2025 at 11:38, Josua Mayer <josua@solid-run.com> wrote:
>
> Hi Ulf,
>
> Am 17.12.25 um 14:38 schrieb Ulf Hansson:
> > On Wed, 10 Dec 2025 at 18:39, Josua Mayer <josua@solid-run.com> wrote:
>
> cut
>
> >>  /*
> >>   * 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 2e25c838f8312..a5da2e33a45c0 100644
> >> --- a/include/linux/mux/consumer.h
> >> +++ b/include/linux/mux/consumer.h
> >> @@ -60,5 +60,9 @@ 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_optional_selected(struct device *dev,
> >> +                                                      const char *mux_name);
> > Seems like we need stub-functions of these too. Otherwise
> > subsystems/drivers need to have a "depends on MULTIPLEXER" in their
> > Kconfigs.
>
> Currently the drivers that can use a mux select MULTIPLEXER in Kconfig.

Yes, but that's not generally how we do this. The driver may not need
MULTIPLEXER for all platforms that driver is being used on.

>
> There already exist a few mux helpers both for mux-state and for mux-control,
> and they might all need stubs.

Correct. I think we should add subs for all of them.

>
> I'd prefer the restructuring of kconfig dependencies being independent from
> adding mux-state functionality to renesas sdhi driver.

I understand your point, but adding the stubs isn't really a big thing
- unless someone has some good arguments not to!?

Moreover, since the series changes the mux-core anyways - and
subsequent changes depend on it, I don't see an issue to fold in yet
another patch to add the stubs.

Kind regards
Uffe

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Re: [PATCH v3 1/6] phy: can-transceiver: rename temporary helper function to avoid conflict

[Vinod Koul]

On 10-12-25, 18:38, Josua Mayer wrote:
> Rename the temporary devm_mux_state_get_optional function to avoid
> conflict with upcoming implementation in multiplexer subsystem.

Acked-by: Vinod Koul <vkoul@kernel.org>


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Re: [PATCH v3 3/6] phy: can-transceiver: drop temporary helper getting optional mux-state

[Vinod Koul]

On 10-12-25, 18:38, Josua Mayer wrote:
> Multiplexer subsystem has now added helpers for getting managed optional
> mux-state.

Acked-by: Vinod Koul <vkoul@kernel.org>


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Re: [PATCH v3 4/6] i2c: omap: switch to new generic helper for getting selected mux-state

[Andreas Kemnade]

On Wed, 10 Dec 2025 18:38:38 +0100
Josua Mayer <josua@solid-run.com> wrote:

> Multiplexer subsystem has added generic helper functiosn for getting an
> already selected mux-state object.
> 
> Replace existing logic in probe with the equivalent helper function.
> 
> This change is only compile-tested.
> 
> Signed-off-by: Josua Mayer <josua@solid-run.com>

Reviewed-by: Andreas Kemnade <andreas@kemnade.info>


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Re: [PATCH v3 2/6] mux: Add helper functions for getting optional and selected mux-state

[Josua Mayer]

Am 22.12.25 um 15:47 schrieb Ulf Hansson:
> On Sun, 21 Dec 2025 at 11:38, Josua Mayer <josua@solid-run.com> wrote:
>> Hi Ulf,
>>
>> Am 17.12.25 um 14:38 schrieb Ulf Hansson:
>>> On Wed, 10 Dec 2025 at 18:39, Josua Mayer <josua@solid-run.com> wrote:
>> cut
>>
>>>>  /*
>>>>   * 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 2e25c838f8312..a5da2e33a45c0 100644
>>>> --- a/include/linux/mux/consumer.h
>>>> +++ b/include/linux/mux/consumer.h
>>>> @@ -60,5 +60,9 @@ 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_optional_selected(struct device *dev,
>>>> +                                                      const char *mux_name);
>>> Seems like we need stub-functions of these too. Otherwise
>>> subsystems/drivers need to have a "depends on MULTIPLEXER" in their
>>> Kconfigs.
>> Currently the drivers that can use a mux select MULTIPLEXER in Kconfig.
> Yes, but that's not generally how we do this. The driver may not need
> MULTIPLEXER for all platforms that driver is being used on.
>
>> There already exist a few mux helpers both for mux-state and for mux-control,
>> and they might all need stubs.
> Correct. I think we should add subs for all of them.
>
>> I'd prefer the restructuring of kconfig dependencies being independent from
>> adding mux-state functionality to renesas sdhi driver.
> I understand your point, but adding the stubs isn't really a big thing
> - unless someone has some good arguments not to!?
>
> Moreover, since the series changes the mux-core anyways - and
> subsequent changes depend on it, I don't see an issue to fold in yet
> another patch to add the stubs.
Would this also cause changing all the Kconfig "select MULTIPLEXER"?
If it is only the stubs - sure.

And then in the renesas sdhi patch I can drop my change to kconfig.

sincerely
Josua Mayer
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Re: [PATCH v3 2/6] mux: Add helper functions for getting optional and selected mux-state

[Josua Mayer]

Am 22.12.25 um 11:08 schrieb Geert Uytterhoeven:
> Hi Josua,
>
> On Wed, 10 Dec 2025 at 18:39, 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:
>>
>> - devm_mux_state_get_optional:
>>   Get a mux-state if specified in dt, return NULL 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 return -ENOENT in case dt
>> did not specify a mux-state or -control matching given name (if valid).
>> This matches of_parse_phandle_with_args semantics which also returns
>> -ENOENT if the property does nto exists, or its value is zero.
>>
>> The new helper functions check for ENOENT to return NULL for optional
>> muxes.
>>
>> 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. This is removed as the returned error code (-ENOENT) is clear.
>>
>> The second error message is based on of_parse_phandle_with_args return
>> value. In case mux description is missing from DT, it returns -ENOENT.
>> Print error message only for other error codes.
>>
>> This ensures that the new helper functions will not confuse the user
>> either.
>>
>> Signed-off-by: Josua Mayer <josua@solid-run.com>
> Thanks for your patch!
>
>> --- a/drivers/mux/core.c
>> +++ b/drivers/mux/core.c
>> @@ -542,11 +542,8 @@ 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) {
>> -                       dev_err(dev, "mux controller '%s' not found\n",
>> -                               mux_name);
>> -                       return ERR_PTR(index);
>> -               }
>> +               if (index < 0)
>> +                       return ERR_PTR(-ENOENT);
>>         }
>>
>>         if (state)
>> @@ -558,8 +555,10 @@ static struct mux_control *mux_get(struct device *dev, const char *mux_name,
>>                                                  "mux-controls", "#mux-control-cells",
>>                                                  index, &args);
>>         if (ret) {
>> -               dev_err(dev, "%pOF: failed to get mux-%s %s(%i)\n",
>> -                       np, state ? "state" : "control", mux_name ?: "", index);
>> +               if (ret != -ENOENT)
> I think the non-optional variant should still print an error message in
> case of -ENOENT, else this has to be duplicated in all drivers using it.
>
> This is typically handled by having a non-printing core helper function,
> and having printing non-optional, and non-printing/ignoring optional wrappers
> around the former.

I would prefer letting drivers use dev_err_probe.
Silent helper functions can more easily share code between them ...

If this is a strong preference I can rework the error behaviour and modify
the relevant mux_state_get and mux_control_get.

>
>> +                       dev_err(dev, "%pOF: failed to get mux-%s %s(%i)\n",
>> +                               np, state ? "state" : "control",
>> +                               mux_name ?: "", index);
>>                 return ERR_PTR(ret);
>>         }
>>
> Gr{oetje,eeting}s,
>
>                         Geert
>
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Re: [PATCH v3 2/6] mux: Add helper functions for getting optional and selected mux-state

[Josua Mayer]

Am 29.12.25 um 13:01 schrieb Josua Mayer:
> Am 22.12.25 um 11:08 schrieb Geert Uytterhoeven:
>> Hi Josua,
>>
>> On Wed, 10 Dec 2025 at 18:39, 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:
>>>
>>> - devm_mux_state_get_optional:
>>>   Get a mux-state if specified in dt, return NULL 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 return -ENOENT in case dt
>>> did not specify a mux-state or -control matching given name (if valid).
>>> This matches of_parse_phandle_with_args semantics which also returns
>>> -ENOENT if the property does nto exists, or its value is zero.
>>>
>>> The new helper functions check for ENOENT to return NULL for optional
>>> muxes.
>>>
>>> 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. This is removed as the returned error code (-ENOENT) is clear.
>>>
>>> The second error message is based on of_parse_phandle_with_args return
>>> value. In case mux description is missing from DT, it returns -ENOENT.
>>> Print error message only for other error codes.
>>>
>>> This ensures that the new helper functions will not confuse the user
>>> either.
>>>
>>> Signed-off-by: Josua Mayer <josua@solid-run.com>
>> Thanks for your patch!
>>
>>> --- a/drivers/mux/core.c
>>> +++ b/drivers/mux/core.c
>>> @@ -542,11 +542,8 @@ 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) {
>>> -                       dev_err(dev, "mux controller '%s' not found\n",
>>> -                               mux_name);
>>> -                       return ERR_PTR(index);
>>> -               }
>>> +               if (index < 0)
>>> +                       return ERR_PTR(-ENOENT);
>>>         }
>>>
>>>         if (state)
>>> @@ -558,8 +555,10 @@ static struct mux_control *mux_get(struct device *dev, const char *mux_name,
>>>                                                  "mux-controls", "#mux-control-cells",
>>>                                                  index, &args);
>>>         if (ret) {
>>> -               dev_err(dev, "%pOF: failed to get mux-%s %s(%i)\n",
>>> -                       np, state ? "state" : "control", mux_name ?: "", index);
>>> +               if (ret != -ENOENT)
>> I think the non-optional variant should still print an error message in
>> case of -ENOENT, else this has to be duplicated in all drivers using it.
>>
>> This is typically handled by having a non-printing core helper function,
>> and having printing non-optional, and non-printing/ignoring optional wrappers
>> around the former.
> I would prefer letting drivers use dev_err_probe.
> Silent helper functions can more easily share code between them ...
>
> If this is a strong preference I can rework the error behaviour and modify
> the relevant mux_state_get and mux_control_get.
Thinking further ... The main issue is that the core mux_get functio is quite
verbose printing message for each error condition.

Now I have silenced the ENOENT case - because it should be silent for optional
muxes.

So ... actually I propose to update direct callers of mux_get function,
and re-add error message specifically for non-optional variants in case of ENOENT.

>
>>> +                       dev_err(dev, "%pOF: failed to get mux-%s %s(%i)\n",
>>> +                               np, state ? "state" : "control",
>>> +                               mux_name ?: "", index);
>>>                 return ERR_PTR(ret);
>>>         }
>>>
>> Gr{oetje,eeting}s,
>>
>>                         Geert
> >
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Re: [PATCH v3 2/6] mux: Add helper functions for getting optional and selected mux-state

[Ulf Hansson]

On Mon, 29 Dec 2025 at 12:30, Josua Mayer <josua@solid-run.com> wrote:
>
> Am 22.12.25 um 15:47 schrieb Ulf Hansson:
> > On Sun, 21 Dec 2025 at 11:38, Josua Mayer <josua@solid-run.com> wrote:
> >> Hi Ulf,
> >>
> >> Am 17.12.25 um 14:38 schrieb Ulf Hansson:
> >>> On Wed, 10 Dec 2025 at 18:39, Josua Mayer <josua@solid-run.com> wrote:
> >> cut
> >>
> >>>>  /*
> >>>>   * 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 2e25c838f8312..a5da2e33a45c0 100644
> >>>> --- a/include/linux/mux/consumer.h
> >>>> +++ b/include/linux/mux/consumer.h
> >>>> @@ -60,5 +60,9 @@ 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_optional_selected(struct device *dev,
> >>>> +                                                      const char *mux_name);
> >>> Seems like we need stub-functions of these too. Otherwise
> >>> subsystems/drivers need to have a "depends on MULTIPLEXER" in their
> >>> Kconfigs.
> >> Currently the drivers that can use a mux select MULTIPLEXER in Kconfig.
> > Yes, but that's not generally how we do this. The driver may not need
> > MULTIPLEXER for all platforms that driver is being used on.
> >
> >> There already exist a few mux helpers both for mux-state and for mux-control,
> >> and they might all need stubs.
> > Correct. I think we should add subs for all of them.
> >
> >> I'd prefer the restructuring of kconfig dependencies being independent from
> >> adding mux-state functionality to renesas sdhi driver.
> > I understand your point, but adding the stubs isn't really a big thing
> > - unless someone has some good arguments not to!?
> >
> > Moreover, since the series changes the mux-core anyways - and
> > subsequent changes depend on it, I don't see an issue to fold in yet
> > another patch to add the stubs.
> Would this also cause changing all the Kconfig "select MULTIPLEXER"?
> If it is only the stubs - sure.
>
> And then in the renesas sdhi patch I can drop my change to kconfig.

Correct!

Typically, it's better to do a "select MULTIPLEXER" in the platform's
Kconfig for those platforms that really need it.

Kind regards
Uffe

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