[PATCH net-next v3 0/4] net: mdio: implement optional PHY reset before MDIO access

[PATCH net-next v3 0/4] net: mdio: implement optional PHY reset before MDIO access

[Buday Csaba]

Some Ethernet PHY devices require a hard reset before any MDIO access can
be safely performed. This includes the auto-detection of the PHY ID, which
is necessary to bind the correct driver to the device.

The kernel currently does not provide a way to assert the reset before
reading the ID, making these devices usable only when the ID is hardcoded
in the Device Tree 'compatible' string.
(One notable exception is the FEC driver and its now deprecated
`phy-reset-gpios` property).

This patchset implements an optional reset before reading of the PHY ID
register, allowing such PHYs to be used with auto-detected ID. The reset
is controlled by a newly defined DT property, so it should not break
compatibility with existing systems.

There have been several earlier attempts to implement such functionality,
of which I have collected a few in the links section.

The links to my own v1 and v2 versions are also provided.

Link: https://lore.kernel.org/lkml/1499346330-12166-2-git-send-email-richard.leitner@skidata.com/
Link: https://lore.kernel.org/all/20230405-net-next-topic-net-phy-reset-v1-0-7e5329f08002@pengutronix.de/
Link: https://lore.kernel.org/netdev/20250709133222.48802-4-buday.csaba@prolan.hu/
Link: https://lore.kernel.org/all/20251013135557.62949-1-buday.csaba@prolan.hu/
Link: https://lore.kernel.org/all/20251015134503.107925-1-buday.csaba@prolan.hu/

Buday Csaba (4):
  net: mdio: common handling of phy reset properties
  net: mdio: change property read from fwnode_property_read_u32() to
    device_property_read_u32()
  dt-bindings: net: mdio: add phy-id-read-needs-reset property
  net: mdio: reset PHY before attempting to access registers in
    fwnode_mdiobus_register_phy

 .../devicetree/bindings/net/ethernet-phy.yaml |  8 +++
 drivers/net/mdio/fwnode_mdio.c                | 40 +++++++++++---
 drivers/net/phy/mdio_bus.c                    | 39 +-------------
 drivers/net/phy/mdio_device.c                 | 52 +++++++++++++++++++
 include/linux/mdio.h                          |  2 +
 5 files changed, 98 insertions(+), 43 deletions(-)


base-commit: 00922eeaca3c5c2001781bcad40e0bd54d0fdbb6
-- 
2.39.5

[PATCH net-next v3 1/4] net: mdio: common handling of phy reset properties

[Buday Csaba]

Reset properties of an `mdio_device` are initialized in multiple
source files and multiple functions:
  - `reset_assert_delay` and `reset_deassert_delay` are in
    fwnode_mdio.c
  - `reset_gpio` and `reset_ctrl` are in mdio_bus.c, but handled by
    different functions

This patch unifies the handling of all these properties into two
functions.
mdiobus_register_gpiod() and mdiobus_register_reset() are removed,
while mdio_device_register_reset() and mdio_device_unregister_reset()
are introduced instead.
These functions handle both reset-controllers and reset-gpios, and
also read the corresponding properties from the device tree.
These changes should make tracking the reset properties easier.

The reset logic is unaltered, and should work as it did before.

Signed-off-by: Buday Csaba <buday.csaba@prolan.hu>
---
V2 -> V3: fixed kernel-doc warnings
V1 -> V2: the return value of mdio_device_unregister_reset() is made void
---
 drivers/net/mdio/fwnode_mdio.c |  5 ----
 drivers/net/phy/mdio_bus.c     | 39 ++-----------------------
 drivers/net/phy/mdio_device.c  | 52 ++++++++++++++++++++++++++++++++++
 include/linux/mdio.h           |  2 ++
 4 files changed, 56 insertions(+), 42 deletions(-)

diff --git a/drivers/net/mdio/fwnode_mdio.c b/drivers/net/mdio/fwnode_mdio.c
index 9b41d4697..ba7091518 100644
--- a/drivers/net/mdio/fwnode_mdio.c
+++ b/drivers/net/mdio/fwnode_mdio.c
@@ -92,11 +92,6 @@ int fwnode_mdiobus_phy_device_register(struct mii_bus *mdio,
 	if (fwnode_property_read_bool(child, "broken-turn-around"))
 		mdio->phy_ignore_ta_mask |= 1 << addr;
 
-	fwnode_property_read_u32(child, "reset-assert-us",
-				 &phy->mdio.reset_assert_delay);
-	fwnode_property_read_u32(child, "reset-deassert-us",
-				 &phy->mdio.reset_deassert_delay);
-
 	/* Associate the fwnode with the device structure so it
 	 * can be looked up later
 	 */
diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
index cad6ed3aa..cc3f9cfb1 100644
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c
@@ -33,33 +33,6 @@
 #define CREATE_TRACE_POINTS
 #include <trace/events/mdio.h>
 
-static int mdiobus_register_gpiod(struct mdio_device *mdiodev)
-{
-	/* Deassert the optional reset signal */
-	mdiodev->reset_gpio = gpiod_get_optional(&mdiodev->dev,
-						 "reset", GPIOD_OUT_LOW);
-	if (IS_ERR(mdiodev->reset_gpio))
-		return PTR_ERR(mdiodev->reset_gpio);
-
-	if (mdiodev->reset_gpio)
-		gpiod_set_consumer_name(mdiodev->reset_gpio, "PHY reset");
-
-	return 0;
-}
-
-static int mdiobus_register_reset(struct mdio_device *mdiodev)
-{
-	struct reset_control *reset;
-
-	reset = reset_control_get_optional_exclusive(&mdiodev->dev, "phy");
-	if (IS_ERR(reset))
-		return PTR_ERR(reset);
-
-	mdiodev->reset_ctrl = reset;
-
-	return 0;
-}
-
 int mdiobus_register_device(struct mdio_device *mdiodev)
 {
 	int err;
@@ -68,16 +41,9 @@ int mdiobus_register_device(struct mdio_device *mdiodev)
 		return -EBUSY;
 
 	if (mdiodev->flags & MDIO_DEVICE_FLAG_PHY) {
-		err = mdiobus_register_gpiod(mdiodev);
+		err = mdio_device_register_reset(mdiodev);
 		if (err)
 			return err;
-
-		err = mdiobus_register_reset(mdiodev);
-		if (err)
-			return err;
-
-		/* Assert the reset signal */
-		mdio_device_reset(mdiodev, 1);
 	}
 
 	mdiodev->bus->mdio_map[mdiodev->addr] = mdiodev;
@@ -91,8 +57,7 @@ int mdiobus_unregister_device(struct mdio_device *mdiodev)
 	if (mdiodev->bus->mdio_map[mdiodev->addr] != mdiodev)
 		return -EINVAL;
 
-	gpiod_put(mdiodev->reset_gpio);
-	reset_control_put(mdiodev->reset_ctrl);
+	mdio_device_unregister_reset(mdiodev);
 
 	mdiodev->bus->mdio_map[mdiodev->addr] = NULL;
 
diff --git a/drivers/net/phy/mdio_device.c b/drivers/net/phy/mdio_device.c
index f64176e0e..fb1cb7a26 100644
--- a/drivers/net/phy/mdio_device.c
+++ b/drivers/net/phy/mdio_device.c
@@ -74,6 +74,58 @@ struct mdio_device *mdio_device_create(struct mii_bus *bus, int addr)
 }
 EXPORT_SYMBOL(mdio_device_create);
 
+/**
+ * mdio_device_register_reset - Read and initialize the reset properties of
+ *				an mdio device
+ * @mdiodev: mdio_device structure
+ *
+ * Return: Zero if successful, negative error code on failure
+ */
+int mdio_device_register_reset(struct mdio_device *mdiodev)
+{
+	struct reset_control *reset;
+
+	/* Read optional firmware properties */
+	fwnode_property_read_u32(dev_fwnode(&mdiodev->dev), "reset-assert-us",
+				 &mdiodev->reset_assert_delay);
+	fwnode_property_read_u32(dev_fwnode(&mdiodev->dev), "reset-deassert-us",
+				 &mdiodev->reset_deassert_delay);
+
+	/* reset-gpio, bring up deasserted */
+	mdiodev->reset_gpio = gpiod_get_optional(&mdiodev->dev, "reset",
+						 GPIOD_OUT_LOW);
+
+	if (IS_ERR(mdiodev->reset_gpio))
+		return PTR_ERR(mdiodev->reset_gpio);
+
+	if (mdiodev->reset_gpio)
+		gpiod_set_consumer_name(mdiodev->reset_gpio, "PHY reset");
+
+	reset = reset_control_get_optional_exclusive(&mdiodev->dev, "phy");
+	if (IS_ERR(reset))
+		return PTR_ERR(reset);
+
+	mdiodev->reset_ctrl = reset;
+
+	/* Assert the reset signal */
+	mdio_device_reset(mdiodev, 1);
+
+	return 0;
+}
+EXPORT_SYMBOL(mdio_device_register_reset);
+
+/**
+ * mdio_device_unregister_reset - uninitialize the reset properties of
+ *				  an mdio device
+ * @mdiodev: mdio_device structure
+ */
+void mdio_device_unregister_reset(struct mdio_device *mdiodev)
+{
+	gpiod_put(mdiodev->reset_gpio);
+	reset_control_put(mdiodev->reset_ctrl);
+}
+EXPORT_SYMBOL(mdio_device_unregister_reset);
+
 /**
  * mdio_device_register - Register the mdio device on the MDIO bus
  * @mdiodev: mdio_device structure to be added to the MDIO bus
diff --git a/include/linux/mdio.h b/include/linux/mdio.h
index 42d6d47e4..d81b63fc7 100644
--- a/include/linux/mdio.h
+++ b/include/linux/mdio.h
@@ -90,6 +90,8 @@ static inline void *mdiodev_get_drvdata(struct mdio_device *mdio)
 
 void mdio_device_free(struct mdio_device *mdiodev);
 struct mdio_device *mdio_device_create(struct mii_bus *bus, int addr);
+int mdio_device_register_reset(struct mdio_device *mdiodev);
+void mdio_device_unregister_reset(struct mdio_device *mdiodev);
 int mdio_device_register(struct mdio_device *mdiodev);
 void mdio_device_remove(struct mdio_device *mdiodev);
 void mdio_device_reset(struct mdio_device *mdiodev, int value);
-- 
2.39.5

[PATCH net-next v3 2/4] net: mdio: change property read from fwnode_property_read_u32() to device_property_read_u32()

[Buday Csaba]

Changed fwnode_property_read_u32() in mdio_device_register_reset()
to device_property_read_u32(), which is more appropriate here.

Signed-off-by: Buday Csaba <buday.csaba@prolan.hu>
---
V2 -> V3: unmodified
V1 -> V2: added new patch based on maintainer request
---
 drivers/net/phy/mdio_device.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/phy/mdio_device.c b/drivers/net/phy/mdio_device.c
index fb1cb7a26..5d39b25b7 100644
--- a/drivers/net/phy/mdio_device.c
+++ b/drivers/net/phy/mdio_device.c
@@ -86,9 +86,9 @@ int mdio_device_register_reset(struct mdio_device *mdiodev)
 	struct reset_control *reset;
 
 	/* Read optional firmware properties */
-	fwnode_property_read_u32(dev_fwnode(&mdiodev->dev), "reset-assert-us",
+	device_property_read_u32(&mdiodev->dev, "reset-assert-us",
 				 &mdiodev->reset_assert_delay);
-	fwnode_property_read_u32(dev_fwnode(&mdiodev->dev), "reset-deassert-us",
+	device_property_read_u32(&mdiodev->dev, "reset-deassert-us",
 				 &mdiodev->reset_deassert_delay);
 
 	/* reset-gpio, bring up deasserted */
-- 
2.39.5

[PATCH net-next v3 3/4] dt-bindings: net: mdio: add phy-id-read-needs-reset property

[Buday Csaba]

Some Ethernet PHYs require a hard reset before accessing their MDIO
registers. When the ID is not provided by a compatible string,
reading the PHY ID may fail on such devices.

This patch introduces a new device tree property called
`phy-id-read-needs-reset`, which can be used to hard reset the
PHY before attempting to read its ID via MDIO.

Signed-off-by: Buday Csaba <buday.csaba@prolan.hu>
---
V2 -> V3: unchanged
V1 -> V2: added this DT binding
---
 Documentation/devicetree/bindings/net/ethernet-phy.yaml | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/Documentation/devicetree/bindings/net/ethernet-phy.yaml b/Documentation/devicetree/bindings/net/ethernet-phy.yaml
index 2ec2d9fda..b570f8038 100644
--- a/Documentation/devicetree/bindings/net/ethernet-phy.yaml
+++ b/Documentation/devicetree/bindings/net/ethernet-phy.yaml
@@ -215,6 +215,14 @@ properties:
       Delay after the reset was deasserted in microseconds. If
       this property is missing the delay will be skipped.
 
+  phy-id-read-needs-reset:
+    $ref: /schemas/types.yaml#/definitions/flag
+    description:
+      Some PHYs require a hard reset before accessing MDIO registers.
+      This workaround allows auto-detection of the PHY ID in such cases.
+      When the PHY ID is provided with the 'compatible' string, setting
+      this property has no effect.
+
   sfp:
     $ref: /schemas/types.yaml#/definitions/phandle
     description:
-- 
2.39.5

[PATCH net-next v3 4/4] net: mdio: reset PHY before attempting to access registers in fwnode_mdiobus_register_phy

[Buday Csaba]

Implement support for the `phy-id-read-needs-reset` device tree
property.

When the ID of an ethernet PHY is not provided by the 'compatible'
string in the device tree, its actual ID is read via the MDIO bus.
For some PHYs this could be unsafe, since a hard reset may be
necessary to safely access the MDIO registers.

This patch performs the hard-reset before attempting to read the ID,
when the mentioned device tree property is present.

Signed-off-by: Buday Csaba <buday.csaba@prolan.hu>
---
V2 -> V3: kernel-doc replaced with a comment (fixed warning)
V1 -> V2:
 - renamed DT property `reset-phy-before-probe` to
  `phy-id-read-needs-reset`
 - renamed fwnode_reset_phy_before_probe() to
   fwnode_reset_phy()
 - added kernel-doc for fwnode_reset_phy()
 - improved error handling in fwnode_reset_phy()
---
 drivers/net/mdio/fwnode_mdio.c | 35 +++++++++++++++++++++++++++++++++-
 1 file changed, 34 insertions(+), 1 deletion(-)

diff --git a/drivers/net/mdio/fwnode_mdio.c b/drivers/net/mdio/fwnode_mdio.c
index ba7091518..8e8f9182a 100644
--- a/drivers/net/mdio/fwnode_mdio.c
+++ b/drivers/net/mdio/fwnode_mdio.c
@@ -114,6 +114,36 @@ int fwnode_mdiobus_phy_device_register(struct mii_bus *mdio,
 }
 EXPORT_SYMBOL(fwnode_mdiobus_phy_device_register);
 
+/* Hard-reset a PHY before registration */
+static int fwnode_reset_phy(struct mii_bus *bus, u32 addr,
+			    struct fwnode_handle *phy_node)
+{
+	struct mdio_device *tmpdev;
+	int err;
+
+	tmpdev = mdio_device_create(bus, addr);
+	if (IS_ERR(tmpdev))
+		return PTR_ERR(tmpdev);
+
+	fwnode_handle_get(phy_node);
+	device_set_node(&tmpdev->dev, phy_node);
+	err = mdio_device_register_reset(tmpdev);
+	if (err) {
+		mdio_device_free(tmpdev);
+		return err;
+	}
+
+	mdio_device_reset(tmpdev, 1);
+	mdio_device_reset(tmpdev, 0);
+
+	mdio_device_unregister_reset(tmpdev);
+
+	mdio_device_free(tmpdev);
+	fwnode_handle_put(phy_node);
+
+	return 0;
+}
+
 int fwnode_mdiobus_register_phy(struct mii_bus *bus,
 				struct fwnode_handle *child, u32 addr)
 {
@@ -129,8 +159,11 @@ int fwnode_mdiobus_register_phy(struct mii_bus *bus,
 		return PTR_ERR(mii_ts);
 
 	is_c45 = fwnode_device_is_compatible(child, "ethernet-phy-ieee802.3-c45");
-	if (is_c45 || fwnode_get_phy_id(child, &phy_id))
+	if (is_c45 || fwnode_get_phy_id(child, &phy_id)) {
+		if (fwnode_property_present(child, "reset-phy-before-probe"))
+			fwnode_reset_phy(bus, addr, child);
 		phy = get_phy_device(bus, addr, is_c45);
+	}
 	else
 		phy = phy_device_create(bus, addr, phy_id, 0, NULL);
 	if (IS_ERR(phy)) {
-- 
2.39.5

Re: [PATCH net-next v3 4/4] net: mdio: reset PHY before attempting to access registers in fwnode_mdiobus_register_phy

[Philipp Zabel]

On Fr, 2025-10-17 at 18:10 +0200, Buday Csaba wrote:
> Implement support for the `phy-id-read-needs-reset` device tree
> property.
> 
> When the ID of an ethernet PHY is not provided by the 'compatible'
> string in the device tree, its actual ID is read via the MDIO bus.
> For some PHYs this could be unsafe, since a hard reset may be
> necessary to safely access the MDIO registers.
> 
> This patch performs the hard-reset before attempting to read the ID,
> when the mentioned device tree property is present.
> 
> Signed-off-by: Buday Csaba <buday.csaba@prolan.hu>
> ---
> V2 -> V3: kernel-doc replaced with a comment (fixed warning)
> V1 -> V2:
>  - renamed DT property `reset-phy-before-probe` to
>   `phy-id-read-needs-reset`

Not completely, see below.

>  - renamed fwnode_reset_phy_before_probe() to
>    fwnode_reset_phy()
>  - added kernel-doc for fwnode_reset_phy()
>  - improved error handling in fwnode_reset_phy()
> ---
>  drivers/net/mdio/fwnode_mdio.c | 35 +++++++++++++++++++++++++++++++++-
>  1 file changed, 34 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/mdio/fwnode_mdio.c b/drivers/net/mdio/fwnode_mdio.c
> index ba7091518..8e8f9182a 100644
> --- a/drivers/net/mdio/fwnode_mdio.c
> +++ b/drivers/net/mdio/fwnode_mdio.c
> @@ -114,6 +114,36 @@ int fwnode_mdiobus_phy_device_register(struct mii_bus *mdio,
>  }
>  EXPORT_SYMBOL(fwnode_mdiobus_phy_device_register);
>  
> +/* Hard-reset a PHY before registration */
> +static int fwnode_reset_phy(struct mii_bus *bus, u32 addr,
> +			    struct fwnode_handle *phy_node)
> +{
> +	struct mdio_device *tmpdev;
> +	int err;
> +
> +	tmpdev = mdio_device_create(bus, addr);
> +	if (IS_ERR(tmpdev))
> +		return PTR_ERR(tmpdev);
> +
> +	fwnode_handle_get(phy_node);
> +	device_set_node(&tmpdev->dev, phy_node);
> +	err = mdio_device_register_reset(tmpdev);
> +	if (err) {
> +		mdio_device_free(tmpdev);
> +		return err;
> +	}
> +
> +	mdio_device_reset(tmpdev, 1);
> +	mdio_device_reset(tmpdev, 0);
> +
> +	mdio_device_unregister_reset(tmpdev);
> +
> +	mdio_device_free(tmpdev);
> +	fwnode_handle_put(phy_node);
> +
> +	return 0;
> +}
> +
>  int fwnode_mdiobus_register_phy(struct mii_bus *bus,
>  				struct fwnode_handle *child, u32 addr)
>  {
> @@ -129,8 +159,11 @@ int fwnode_mdiobus_register_phy(struct mii_bus *bus,
>  		return PTR_ERR(mii_ts);
>  
>  	is_c45 = fwnode_device_is_compatible(child, "ethernet-phy-ieee802.3-c45");
> -	if (is_c45 || fwnode_get_phy_id(child, &phy_id))
> +	if (is_c45 || fwnode_get_phy_id(child, &phy_id)) {
> +		if (fwnode_property_present(child, "reset-phy-before-probe"))

Commit message says this should be "phy-id-read-needs-reset" now.

regards
Philipp

Re: [PATCH net-next v3 4/4] net: mdio: reset PHY before attempting to access registers in fwnode_mdiobus_register_phy

[Buday Csaba]

Thank you!
I do not know how that slipped.
I will fix it in v4.

Regards,
Csaba

On Mon, Oct 20, 2025 at 11:16:11AM +0200, Philipp Zabel wrote:
> On Fr, 2025-10-17 at 18:10 +0200, Buday Csaba wrote:
> > Implement support for the `phy-id-read-needs-reset` device tree
> > property.
> > 
> > When the ID of an ethernet PHY is not provided by the 'compatible'
> > string in the device tree, its actual ID is read via the MDIO bus.
> > For some PHYs this could be unsafe, since a hard reset may be
> > necessary to safely access the MDIO registers.
> > 
> > This patch performs the hard-reset before attempting to read the ID,
> > when the mentioned device tree property is present.
> > 
> > Signed-off-by: Buday Csaba <buday.csaba@prolan.hu>
> > ---
> > V2 -> V3: kernel-doc replaced with a comment (fixed warning)
> > V1 -> V2:
> >  - renamed DT property `reset-phy-before-probe` to
> >   `phy-id-read-needs-reset`
> 
> Not completely, see below.
> 
> >  - renamed fwnode_reset_phy_before_probe() to
> >    fwnode_reset_phy()
> >  - added kernel-doc for fwnode_reset_phy()
> >  - improved error handling in fwnode_reset_phy()
> > ---
> >  drivers/net/mdio/fwnode_mdio.c | 35 +++++++++++++++++++++++++++++++++-
> >  1 file changed, 34 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/net/mdio/fwnode_mdio.c b/drivers/net/mdio/fwnode_mdio.c
> > index ba7091518..8e8f9182a 100644
> > --- a/drivers/net/mdio/fwnode_mdio.c
> > +++ b/drivers/net/mdio/fwnode_mdio.c
> > @@ -114,6 +114,36 @@ int fwnode_mdiobus_phy_device_register(struct mii_bus *mdio,
> >  }
> >  EXPORT_SYMBOL(fwnode_mdiobus_phy_device_register);
> >  
> > +/* Hard-reset a PHY before registration */
> > +static int fwnode_reset_phy(struct mii_bus *bus, u32 addr,
> > +			    struct fwnode_handle *phy_node)
> > +{
> > +	struct mdio_device *tmpdev;
> > +	int err;
> > +
> > +	tmpdev = mdio_device_create(bus, addr);
> > +	if (IS_ERR(tmpdev))
> > +		return PTR_ERR(tmpdev);
> > +
> > +	fwnode_handle_get(phy_node);
> > +	device_set_node(&tmpdev->dev, phy_node);
> > +	err = mdio_device_register_reset(tmpdev);
> > +	if (err) {
> > +		mdio_device_free(tmpdev);
> > +		return err;
> > +	}
> > +
> > +	mdio_device_reset(tmpdev, 1);
> > +	mdio_device_reset(tmpdev, 0);
> > +
> > +	mdio_device_unregister_reset(tmpdev);
> > +
> > +	mdio_device_free(tmpdev);
> > +	fwnode_handle_put(phy_node);
> > +
> > +	return 0;
> > +}
> > +
> >  int fwnode_mdiobus_register_phy(struct mii_bus *bus,
> >  				struct fwnode_handle *child, u32 addr)
> >  {
> > @@ -129,8 +159,11 @@ int fwnode_mdiobus_register_phy(struct mii_bus *bus,
> >  		return PTR_ERR(mii_ts);
> >  
> >  	is_c45 = fwnode_device_is_compatible(child, "ethernet-phy-ieee802.3-c45");
> > -	if (is_c45 || fwnode_get_phy_id(child, &phy_id))
> > +	if (is_c45 || fwnode_get_phy_id(child, &phy_id)) {
> > +		if (fwnode_property_present(child, "reset-phy-before-probe"))
> 
> Commit message says this should be "phy-id-read-needs-reset" now.
> 
> regards
> Philipp
> 

Re: [PATCH net-next v3 3/4] dt-bindings: net: mdio: add phy-id-read-needs-reset property

[Rob Herring]

On Fri, Oct 17, 2025 at 06:10:10PM +0200, Buday Csaba wrote:
> Some Ethernet PHYs require a hard reset before accessing their MDIO
> registers. When the ID is not provided by a compatible string,
> reading the PHY ID may fail on such devices.
> 
> This patch introduces a new device tree property called
> `phy-id-read-needs-reset`, which can be used to hard reset the
> PHY before attempting to read its ID via MDIO.

If your phy needs special handling, provide a compatible and use that.

> 
> Signed-off-by: Buday Csaba <buday.csaba@prolan.hu>
> ---
> V2 -> V3: unchanged
> V1 -> V2: added this DT binding
> ---
>  Documentation/devicetree/bindings/net/ethernet-phy.yaml | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/net/ethernet-phy.yaml b/Documentation/devicetree/bindings/net/ethernet-phy.yaml
> index 2ec2d9fda..b570f8038 100644
> --- a/Documentation/devicetree/bindings/net/ethernet-phy.yaml
> +++ b/Documentation/devicetree/bindings/net/ethernet-phy.yaml
> @@ -215,6 +215,14 @@ properties:
>        Delay after the reset was deasserted in microseconds. If
>        this property is missing the delay will be skipped.
>  
> +  phy-id-read-needs-reset:
> +    $ref: /schemas/types.yaml#/definitions/flag
> +    description:
> +      Some PHYs require a hard reset before accessing MDIO registers.
> +      This workaround allows auto-detection of the PHY ID in such cases.
> +      When the PHY ID is provided with the 'compatible' string, setting
> +      this property has no effect.
> +
>    sfp:
>      $ref: /schemas/types.yaml#/definitions/phandle
>      description:
> -- 
> 2.39.5
> 
>