[net-next PATCH v2 0/3] ACPI support for xgmac_mdio drivers.

[net-next PATCH v2 0/3] ACPI support for xgmac_mdio drivers.

[Calvin Johnson]

This patch series provides ACPI support for xgmac_mdio driver.


Changes in v2:
- Reserve "0" to mean that no mdiobus capabilities have been declared.
- bus->id: change to appropriate printk format specifier
- clean up xgmac_acpi_match
- clariy platform_get_resource() usage with comments

Calvin Johnson (1):
  net/fsl: acpize xgmac_mdio

Jeremy Linton (2):
  net: phy: Allow mdio buses to auto-probe c45 devices
  net/fsl: enable extended scanning in xgmac_mdio

 drivers/net/ethernet/freescale/xgmac_mdio.c | 33 ++++++++++++++-------
 drivers/net/phy/mdio_bus.c                  | 17 +++++++++--
 include/linux/phy.h                         |  8 +++++
 3 files changed, 46 insertions(+), 12 deletions(-)

-- 
2.17.1

[net-next PATCH v2 1/3] net: phy: Allow mdio buses to auto-probe c45 devices

[Calvin Johnson]

From: Jeremy Linton <jeremy.linton@arm.com>

The mdiobus_scan logic is currently hardcoded to only
work with c22 devices. This works fairly well in most
cases, but its possible that a c45 device doesn't respond
despite being a standard phy. If the parent hardware
is capable, it makes sense to scan for c22 devices before
falling back to c45.

As we want this to reflect the capabilities of the STA,
lets add a field to the mii_bus structure to represent
the capability. That way devices can opt into the extended
scanning. Existing users should continue to default to c22
only scanning as long as they are zero'ing the structure
before use.

Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
Signed-off-by: Calvin Johnson <calvin.johnson@oss.nxp.com>

---

Changes in v2:
- Reserve "0" to mean that no mdiobus capabilities have been declared.

 drivers/net/phy/mdio_bus.c | 17 +++++++++++++++--
 include/linux/phy.h        |  8 ++++++++
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
index 6ceee82b2839..e6c179b89907 100644
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c
@@ -739,10 +739,23 @@ EXPORT_SYMBOL(mdiobus_free);
  */
 struct phy_device *mdiobus_scan(struct mii_bus *bus, int addr)
 {
-	struct phy_device *phydev;
+	struct phy_device *phydev = ERR_PTR(-ENODEV);
 	int err;
 
-	phydev = get_phy_device(bus, addr, false);
+	switch (bus->probe_capabilities) {
+	case MDIOBUS_C22:
+		phydev = get_phy_device(bus, addr, false);
+		break;
+	case MDIOBUS_C45:
+		phydev = get_phy_device(bus, addr, true);
+		break;
+	case MDIOBUS_C22_C45:
+		phydev = get_phy_device(bus, addr, false);
+		if (IS_ERR(phydev))
+			phydev = get_phy_device(bus, addr, true);
+		break;
+	}
+
 	if (IS_ERR(phydev))
 		return phydev;
 
diff --git a/include/linux/phy.h b/include/linux/phy.h
index 9248dd2ce4ca..7860d56c6bf5 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -298,6 +298,14 @@ struct mii_bus {
 	/* RESET GPIO descriptor pointer */
 	struct gpio_desc *reset_gpiod;
 
+	/* bus capabilities, used for probing */
+	enum {
+		MDIOBUS_NO_CAP = 0,
+		MDIOBUS_C22,
+		MDIOBUS_C45,
+		MDIOBUS_C22_C45,
+	} probe_capabilities;
+
 	/* protect access to the shared element */
 	struct mutex shared_lock;
 
-- 
2.17.1

[net-next PATCH v2 2/3] net/fsl: acpize xgmac_mdio

[Calvin Johnson]

Add ACPI support for xgmac MDIO bus registration while maintaining
the existing DT support.

The function mdiobus_register() inside of_mdiobus_register(), brings
up all the PHYs on the mdio bus and attach them to the bus.

Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
Signed-off-by: Calvin Johnson <calvin.johnson@oss.nxp.com>

---

Changes in v2:
- bus->id: change to appropriate printk format specifier
- clean up xgmac_acpi_match
- clariy platform_get_resource() usage with comments

 drivers/net/ethernet/freescale/xgmac_mdio.c | 32 ++++++++++++++-------
 1 file changed, 22 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ethernet/freescale/xgmac_mdio.c b/drivers/net/ethernet/freescale/xgmac_mdio.c
index c82c85ef5fb3..b4ed5f837975 100644
--- a/drivers/net/ethernet/freescale/xgmac_mdio.c
+++ b/drivers/net/ethernet/freescale/xgmac_mdio.c
@@ -245,14 +245,19 @@ static int xgmac_mdio_probe(struct platform_device *pdev)
 {
 	struct device_node *np = pdev->dev.of_node;
 	struct mii_bus *bus;
-	struct resource res;
+	struct resource *res;
 	struct mdio_fsl_priv *priv;
 	int ret;
 
-	ret = of_address_to_resource(np, 0, &res);
-	if (ret) {
+	/* In DPAA-1, MDIO is one of the many FMan sub-devices. The FMan
+	 * defines a register space that spans a large area, covering all the
+	 * subdevice areas. Therefore, MDIO cannot claim exclusive access to
+	 * this register area.
+	 */
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
 		dev_err(&pdev->dev, "could not obtain address\n");
-		return ret;
+		return -EINVAL;
 	}
 
 	bus = mdiobus_alloc_size(sizeof(struct mdio_fsl_priv));
@@ -263,21 +268,21 @@ static int xgmac_mdio_probe(struct platform_device *pdev)
 	bus->read = xgmac_mdio_read;
 	bus->write = xgmac_mdio_write;
 	bus->parent = &pdev->dev;
-	snprintf(bus->id, MII_BUS_ID_SIZE, "%llx", (unsigned long long)res.start);
+	snprintf(bus->id, MII_BUS_ID_SIZE, "%pa", &res->start);
 
 	/* Set the PHY base address */
 	priv = bus->priv;
-	priv->mdio_base = of_iomap(np, 0);
+	priv->mdio_base = ioremap(res->start, resource_size(res));
 	if (!priv->mdio_base) {
 		ret = -ENOMEM;
 		goto err_ioremap;
 	}
 
-	priv->is_little_endian = of_property_read_bool(pdev->dev.of_node,
-						       "little-endian");
+	priv->is_little_endian = device_property_read_bool(&pdev->dev,
+							   "little-endian");
 
-	priv->has_a011043 = of_property_read_bool(pdev->dev.of_node,
-						  "fsl,erratum-a011043");
+	priv->has_a011043 = device_property_read_bool(&pdev->dev,
+						      "fsl,erratum-a011043");
 
 	ret = of_mdiobus_register(bus, np);
 	if (ret) {
@@ -320,10 +325,17 @@ static const struct of_device_id xgmac_mdio_match[] = {
 };
 MODULE_DEVICE_TABLE(of, xgmac_mdio_match);
 
+static const struct acpi_device_id xgmac_acpi_match[] = {
+	{ "NXP0006" },
+	{ }
+};
+MODULE_DEVICE_TABLE(acpi, xgmac_acpi_match);
+
 static struct platform_driver xgmac_mdio_driver = {
 	.driver = {
 		.name = "fsl-fman_xmdio",
 		.of_match_table = xgmac_mdio_match,
+		.acpi_match_table = xgmac_acpi_match,
 	},
 	.probe = xgmac_mdio_probe,
 	.remove = xgmac_mdio_remove,
-- 
2.17.1

[net-next PATCH v2 3/3] net/fsl: enable extended scanning in xgmac_mdio

[Calvin Johnson]

From: Jeremy Linton <jeremy.linton@arm.com>

Since we know the xgmac hardware always has a c45
compliant bus, let's try scanning for c22 capable
PHYs first. If we fail to find any, then it will
fall back to c45 automatically.

Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
Signed-off-by: Calvin Johnson <calvin.johnson@oss.nxp.com>

---

Changes in v2: None

 drivers/net/ethernet/freescale/xgmac_mdio.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/ethernet/freescale/xgmac_mdio.c b/drivers/net/ethernet/freescale/xgmac_mdio.c
index b4ed5f837975..98be51d8b08c 100644
--- a/drivers/net/ethernet/freescale/xgmac_mdio.c
+++ b/drivers/net/ethernet/freescale/xgmac_mdio.c
@@ -268,6 +268,7 @@ static int xgmac_mdio_probe(struct platform_device *pdev)
 	bus->read = xgmac_mdio_read;
 	bus->write = xgmac_mdio_write;
 	bus->parent = &pdev->dev;
+	bus->probe_capabilities = MDIOBUS_C22_C45;
 	snprintf(bus->id, MII_BUS_ID_SIZE, "%pa", &res->start);
 
 	/* Set the PHY base address */
-- 
2.17.1

RE: [net-next PATCH v2 1/3] net: phy: Allow mdio buses to auto-probe c45 devices

[Madalin Bucur (OSS)]

> -----Original Message-----
> From: Calvin Johnson (OSS) <calvin.johnson@oss.nxp.com>
> Sent: Monday, June 22, 2020 11:19 AM
> To: Jeremy Linton <jeremy.linton@arm.com>; Russell King - ARM Linux admin
> <linux@armlinux.org.uk>; Jon <jon@solid-run.com>; Cristi Sovaiala
> <cristian.sovaiala@nxp.com>; Ioana Ciornei <ioana.ciornei@nxp.com>; Andrew
> Lunn <andrew@lunn.ch>; Andy Shevchenko <andy.shevchenko@gmail.com>;
> Florian Fainelli <f.fainelli@gmail.com>; Madalin Bucur (OSS)
> <madalin.bucur@oss.nxp.com>
> Cc: linux.cj@gmail.com; netdev@vger.kernel.org; Calvin Johnson (OSS)
> <calvin.johnson@oss.nxp.com>
> Subject: [net-next PATCH v2 1/3] net: phy: Allow mdio buses to auto-probe
> c45 devices
> 
> From: Jeremy Linton <jeremy.linton@arm.com>
> 
> The mdiobus_scan logic is currently hardcoded to only
> work with c22 devices. This works fairly well in most
> cases, but its possible that a c45 device doesn't respond
> despite being a standard phy. If the parent hardware
> is capable, it makes sense to scan for c22 devices before
> falling back to c45.
> 
> As we want this to reflect the capabilities of the STA,
> lets add a field to the mii_bus structure to represent
> the capability. That way devices can opt into the extended
> scanning. Existing users should continue to default to c22
> only scanning as long as they are zero'ing the structure
> before use.

How is this default working for existing users, the code below does not seem
to do anything for a zeroed struct, as there is no default in the switch?

> 
> Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
> Signed-off-by: Calvin Johnson <calvin.johnson@oss.nxp.com>
> 
> ---
> 
> Changes in v2:
> - Reserve "0" to mean that no mdiobus capabilities have been declared.
> 
>  drivers/net/phy/mdio_bus.c | 17 +++++++++++++++--
>  include/linux/phy.h        |  8 ++++++++
>  2 files changed, 23 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
> index 6ceee82b2839..e6c179b89907 100644
> --- a/drivers/net/phy/mdio_bus.c
> +++ b/drivers/net/phy/mdio_bus.c
> @@ -739,10 +739,23 @@ EXPORT_SYMBOL(mdiobus_free);
>   */
>  struct phy_device *mdiobus_scan(struct mii_bus *bus, int addr)
>  {
> -	struct phy_device *phydev;
> +	struct phy_device *phydev = ERR_PTR(-ENODEV);
>  	int err;
> 
> -	phydev = get_phy_device(bus, addr, false);
> +	switch (bus->probe_capabilities) {
> +	case MDIOBUS_C22:
> +		phydev = get_phy_device(bus, addr, false);
> +		break;
> +	case MDIOBUS_C45:
> +		phydev = get_phy_device(bus, addr, true);
> +		break;
> +	case MDIOBUS_C22_C45:
> +		phydev = get_phy_device(bus, addr, false);
> +		if (IS_ERR(phydev))
> +			phydev = get_phy_device(bus, addr, true);
> +		break;
> +	}
> +
>  	if (IS_ERR(phydev))
>  		return phydev;
> 
> diff --git a/include/linux/phy.h b/include/linux/phy.h
> index 9248dd2ce4ca..7860d56c6bf5 100644
> --- a/include/linux/phy.h
> +++ b/include/linux/phy.h
> @@ -298,6 +298,14 @@ struct mii_bus {
>  	/* RESET GPIO descriptor pointer */
>  	struct gpio_desc *reset_gpiod;
> 
> +	/* bus capabilities, used for probing */
> +	enum {
> +		MDIOBUS_NO_CAP = 0,
> +		MDIOBUS_C22,
> +		MDIOBUS_C45,
> +		MDIOBUS_C22_C45,
> +	} probe_capabilities;
> +
>  	/* protect access to the shared element */
>  	struct mutex shared_lock;
> 
> --
> 2.17.1

Re: [net-next PATCH v2 1/3] net: phy: Allow mdio buses to auto-probe c45 devices

[kernel test robot]

[-- Attachment #1: Type: text/plain, Size: 3217 bytes --]

Hi Calvin,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on net-next/master]

url:    https://github.com/0day-ci/linux/commits/Calvin-Johnson/ACPI-support-for-xgmac_mdio-drivers/20200622-162324
base:   https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git 29a720c1042f469c8fea317cb5e7f496b116e07d
config: x86_64-allyesconfig (attached as .config)
compiler: clang version 11.0.0 (https://github.com/llvm/llvm-project 1d4c87335d5236ea1f35937e1014980ba961ae34)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # install x86_64 cross compiling tool for clang build
        # apt-get install binutils-x86-64-linux-gnu
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>, old ones prefixed by <<):

>> drivers/net/phy/mdio_bus.c:745:10: warning: enumeration value 'MDIOBUS_NO_CAP' not handled in switch [-Wswitch]
switch (bus->probe_capabilities) {
^
1 warning generated.

vim +/MDIOBUS_NO_CAP +745 drivers/net/phy/mdio_bus.c

   727	
   728	/**
   729	 * mdiobus_scan - scan a bus for MDIO devices.
   730	 * @bus: mii_bus to scan
   731	 * @addr: address on bus to scan
   732	 *
   733	 * This function scans the MDIO bus, looking for devices which can be
   734	 * identified using a vendor/product ID in registers 2 and 3. Not all
   735	 * MDIO devices have such registers, but PHY devices typically
   736	 * do. Hence this function assumes anything found is a PHY, or can be
   737	 * treated as a PHY. Other MDIO devices, such as switches, will
   738	 * probably not be found during the scan.
   739	 */
   740	struct phy_device *mdiobus_scan(struct mii_bus *bus, int addr)
   741	{
   742		struct phy_device *phydev = ERR_PTR(-ENODEV);
   743		int err;
   744	
 > 745		switch (bus->probe_capabilities) {
   746		case MDIOBUS_C22:
   747			phydev = get_phy_device(bus, addr, false);
   748			break;
   749		case MDIOBUS_C45:
   750			phydev = get_phy_device(bus, addr, true);
   751			break;
   752		case MDIOBUS_C22_C45:
   753			phydev = get_phy_device(bus, addr, false);
   754			if (IS_ERR(phydev))
   755				phydev = get_phy_device(bus, addr, true);
   756			break;
   757		}
   758	
   759		if (IS_ERR(phydev))
   760			return phydev;
   761	
   762		/*
   763		 * For DT, see if the auto-probed phy has a correspoding child
   764		 * in the bus node, and set the of_node pointer in this case.
   765		 */
   766		of_mdiobus_link_mdiodev(bus, &phydev->mdio);
   767	
   768		err = phy_device_register(phydev);
   769		if (err) {
   770			phy_device_free(phydev);
   771			return ERR_PTR(-ENODEV);
   772		}
   773	
   774		return phydev;
   775	}
   776	EXPORT_SYMBOL(mdiobus_scan);
   777	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org

[-- Attachment #2: config.gz --]
[-- Type: application/gzip, Size: 75302 bytes --]

Re: [net-next PATCH v2 1/3] net: phy: Allow mdio buses to auto-probe c45 devices

[Calvin Johnson]

On Mon, Jun 22, 2020 at 09:29:17AM +0000, Madalin Bucur (OSS) wrote:
> > -----Original Message-----
> > From: Calvin Johnson (OSS) <calvin.johnson@oss.nxp.com>
> > Sent: Monday, June 22, 2020 11:19 AM
> > To: Jeremy Linton <jeremy.linton@arm.com>; Russell King - ARM Linux admin
> > <linux@armlinux.org.uk>; Jon <jon@solid-run.com>; Cristi Sovaiala
> > <cristian.sovaiala@nxp.com>; Ioana Ciornei <ioana.ciornei@nxp.com>; Andrew
> > Lunn <andrew@lunn.ch>; Andy Shevchenko <andy.shevchenko@gmail.com>;
> > Florian Fainelli <f.fainelli@gmail.com>; Madalin Bucur (OSS)
> > <madalin.bucur@oss.nxp.com>
> > Cc: linux.cj@gmail.com; netdev@vger.kernel.org; Calvin Johnson (OSS)
> > <calvin.johnson@oss.nxp.com>
> > Subject: [net-next PATCH v2 1/3] net: phy: Allow mdio buses to auto-probe
> > c45 devices
> > 
> > From: Jeremy Linton <jeremy.linton@arm.com>
> > 
> > The mdiobus_scan logic is currently hardcoded to only
> > work with c22 devices. This works fairly well in most
> > cases, but its possible that a c45 device doesn't respond
> > despite being a standard phy. If the parent hardware
> > is capable, it makes sense to scan for c22 devices before
> > falling back to c45.
> > 
> > As we want this to reflect the capabilities of the STA,
> > lets add a field to the mii_bus structure to represent
> > the capability. That way devices can opt into the extended
> > scanning. Existing users should continue to default to c22
> > only scanning as long as they are zero'ing the structure
> > before use.
> 
> How is this default working for existing users, the code below does not seem
> to do anything for a zeroed struct, as there is no default in the switch?

Looking further into this, I think MDIOBUS_C22 = 0, was correct. Prior to
this patch, get_phy_device() was executed for C22 in this path. I'll discuss
with Russell and Andrew on this and get back.

> 
> > 
> > Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
> > Signed-off-by: Calvin Johnson <calvin.johnson@oss.nxp.com>
> > 
> > ---
> > 
> > Changes in v2:
> > - Reserve "0" to mean that no mdiobus capabilities have been declared.
> > 
> >  drivers/net/phy/mdio_bus.c | 17 +++++++++++++++--
> >  include/linux/phy.h        |  8 ++++++++
> >  2 files changed, 23 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
> > index 6ceee82b2839..e6c179b89907 100644
> > --- a/drivers/net/phy/mdio_bus.c
> > +++ b/drivers/net/phy/mdio_bus.c
> > @@ -739,10 +739,23 @@ EXPORT_SYMBOL(mdiobus_free);
> >   */
> >  struct phy_device *mdiobus_scan(struct mii_bus *bus, int addr)
> >  {
> > -	struct phy_device *phydev;
> > +	struct phy_device *phydev = ERR_PTR(-ENODEV);
> >  	int err;
> > 
> > -	phydev = get_phy_device(bus, addr, false);
> > +	switch (bus->probe_capabilities) {
> > +	case MDIOBUS_C22:
> > +		phydev = get_phy_device(bus, addr, false);
> > +		break;
> > +	case MDIOBUS_C45:
> > +		phydev = get_phy_device(bus, addr, true);
> > +		break;
> > +	case MDIOBUS_C22_C45:
> > +		phydev = get_phy_device(bus, addr, false);
> > +		if (IS_ERR(phydev))
> > +			phydev = get_phy_device(bus, addr, true);
> > +		break;
> > +	}
> > +
> >  	if (IS_ERR(phydev))
> >  		return phydev;
> > 
> > diff --git a/include/linux/phy.h b/include/linux/phy.h
> > index 9248dd2ce4ca..7860d56c6bf5 100644
> > --- a/include/linux/phy.h
> > +++ b/include/linux/phy.h
> > @@ -298,6 +298,14 @@ struct mii_bus {
> >  	/* RESET GPIO descriptor pointer */
> >  	struct gpio_desc *reset_gpiod;
> > 
> > +	/* bus capabilities, used for probing */
> > +	enum {
> > +		MDIOBUS_NO_CAP = 0,
> > +		MDIOBUS_C22,
> > +		MDIOBUS_C45,
> > +		MDIOBUS_C22_C45,
> > +	} probe_capabilities;
> > +
> >  	/* protect access to the shared element */
> >  	struct mutex shared_lock;
> > 
> > --
> > 2.17.1
> 

Re: [net-next PATCH v2 1/3] net: phy: Allow mdio buses to auto-probe c45 devices

[Russell King - ARM Linux admin]

On Mon, Jun 22, 2020 at 06:46:52PM +0530, Calvin Johnson wrote:
> On Mon, Jun 22, 2020 at 09:29:17AM +0000, Madalin Bucur (OSS) wrote:
> > > -----Original Message-----
> > > From: Calvin Johnson (OSS) <calvin.johnson@oss.nxp.com>
> > > Sent: Monday, June 22, 2020 11:19 AM
> > > To: Jeremy Linton <jeremy.linton@arm.com>; Russell King - ARM Linux admin
> > > <linux@armlinux.org.uk>; Jon <jon@solid-run.com>; Cristi Sovaiala
> > > <cristian.sovaiala@nxp.com>; Ioana Ciornei <ioana.ciornei@nxp.com>; Andrew
> > > Lunn <andrew@lunn.ch>; Andy Shevchenko <andy.shevchenko@gmail.com>;
> > > Florian Fainelli <f.fainelli@gmail.com>; Madalin Bucur (OSS)
> > > <madalin.bucur@oss.nxp.com>
> > > Cc: linux.cj@gmail.com; netdev@vger.kernel.org; Calvin Johnson (OSS)
> > > <calvin.johnson@oss.nxp.com>
> > > Subject: [net-next PATCH v2 1/3] net: phy: Allow mdio buses to auto-probe
> > > c45 devices
> > > 
> > > From: Jeremy Linton <jeremy.linton@arm.com>
> > > 
> > > The mdiobus_scan logic is currently hardcoded to only
> > > work with c22 devices. This works fairly well in most
> > > cases, but its possible that a c45 device doesn't respond
> > > despite being a standard phy. If the parent hardware
> > > is capable, it makes sense to scan for c22 devices before
> > > falling back to c45.
> > > 
> > > As we want this to reflect the capabilities of the STA,
> > > lets add a field to the mii_bus structure to represent
> > > the capability. That way devices can opt into the extended
> > > scanning. Existing users should continue to default to c22
> > > only scanning as long as they are zero'ing the structure
> > > before use.
> > 
> > How is this default working for existing users, the code below does not seem
> > to do anything for a zeroed struct, as there is no default in the switch?
> 
> Looking further into this, I think MDIOBUS_C22 = 0, was correct. Prior to
> this patch, get_phy_device() was executed for C22 in this path. I'll discuss
> with Russell and Andrew on this and get back.

It is not correct for the reasons I stated when I made the comment.
When you introduce "probe_capabilities", every MDIO bus will have
that field as zero.

In your original patch, that means the bus only supports clause 22.
However, we have buses today that _that_ is factually incorrect.
Therefore, introducing probe_capabilities with zero meaning MDIOBUS_C22
is wrong.  It means we can _never_ assume that bus->probe_capabilities
means the bus does not support Clause 45.

Now, as per your patch below, that is better.  It means we're able to
identify those drivers that have not declared which bus access methods
are supported, while we can positively identify those which have.

All that's needed is for your switch() statement to maintain today's
behaviour where no declared probe_capabilities means that the bus
should be probed for clause 22 PHYs.

This means we can later introduce the ability to prevent clause 45
probing for PHYs that declare themselves as explicitly only supporting
clause 22 if we need to without having been backed into a corner, and
left wondering whether the lack of probe_capabilities is because someone
decided "it's zero, so doesn't need to be initialised" and didn't bother
explicitly stating .probe_capabilities = MDIOBUS_C22.

> > > Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
> > > Signed-off-by: Calvin Johnson <calvin.johnson@oss.nxp.com>
> > > 
> > > ---
> > > 
> > > Changes in v2:
> > > - Reserve "0" to mean that no mdiobus capabilities have been declared.
> > > 
> > >  drivers/net/phy/mdio_bus.c | 17 +++++++++++++++--
> > >  include/linux/phy.h        |  8 ++++++++
> > >  2 files changed, 23 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
> > > index 6ceee82b2839..e6c179b89907 100644
> > > --- a/drivers/net/phy/mdio_bus.c
> > > +++ b/drivers/net/phy/mdio_bus.c
> > > @@ -739,10 +739,23 @@ EXPORT_SYMBOL(mdiobus_free);
> > >   */
> > >  struct phy_device *mdiobus_scan(struct mii_bus *bus, int addr)
> > >  {
> > > -	struct phy_device *phydev;
> > > +	struct phy_device *phydev = ERR_PTR(-ENODEV);
> > >  	int err;
> > > 
> > > -	phydev = get_phy_device(bus, addr, false);
> > > +	switch (bus->probe_capabilities) {
> > > +	case MDIOBUS_C22:
> > > +		phydev = get_phy_device(bus, addr, false);
> > > +		break;
> > > +	case MDIOBUS_C45:
> > > +		phydev = get_phy_device(bus, addr, true);
> > > +		break;
> > > +	case MDIOBUS_C22_C45:
> > > +		phydev = get_phy_device(bus, addr, false);
> > > +		if (IS_ERR(phydev))
> > > +			phydev = get_phy_device(bus, addr, true);
> > > +		break;
> > > +	}
> > > +
> > >  	if (IS_ERR(phydev))
> > >  		return phydev;
> > > 
> > > diff --git a/include/linux/phy.h b/include/linux/phy.h
> > > index 9248dd2ce4ca..7860d56c6bf5 100644
> > > --- a/include/linux/phy.h
> > > +++ b/include/linux/phy.h
> > > @@ -298,6 +298,14 @@ struct mii_bus {
> > >  	/* RESET GPIO descriptor pointer */
> > >  	struct gpio_desc *reset_gpiod;
> > > 
> > > +	/* bus capabilities, used for probing */
> > > +	enum {
> > > +		MDIOBUS_NO_CAP = 0,
> > > +		MDIOBUS_C22,
> > > +		MDIOBUS_C45,
> > > +		MDIOBUS_C22_C45,
> > > +	} probe_capabilities;
> > > +
> > >  	/* protect access to the shared element */
> > >  	struct mutex shared_lock;
> > > 
> > > --
> > > 2.17.1
> > 
> 

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Re: [net-next PATCH v2 1/3] net: phy: Allow mdio buses to auto-probe c45 devices

[Calvin Johnson]

On Mon, Jun 22, 2020 at 02:36:19PM +0100, Russell King - ARM Linux admin wrote:
> On Mon, Jun 22, 2020 at 06:46:52PM +0530, Calvin Johnson wrote:
> > On Mon, Jun 22, 2020 at 09:29:17AM +0000, Madalin Bucur (OSS) wrote:
> > > > -----Original Message-----
> > > > From: Calvin Johnson (OSS) <calvin.johnson@oss.nxp.com>
> > > > Sent: Monday, June 22, 2020 11:19 AM
> > > > To: Jeremy Linton <jeremy.linton@arm.com>; Russell King - ARM Linux admin
> > > > <linux@armlinux.org.uk>; Jon <jon@solid-run.com>; Cristi Sovaiala
> > > > <cristian.sovaiala@nxp.com>; Ioana Ciornei <ioana.ciornei@nxp.com>; Andrew
> > > > Lunn <andrew@lunn.ch>; Andy Shevchenko <andy.shevchenko@gmail.com>;
> > > > Florian Fainelli <f.fainelli@gmail.com>; Madalin Bucur (OSS)
> > > > <madalin.bucur@oss.nxp.com>
> > > > Cc: linux.cj@gmail.com; netdev@vger.kernel.org; Calvin Johnson (OSS)
> > > > <calvin.johnson@oss.nxp.com>
> > > > Subject: [net-next PATCH v2 1/3] net: phy: Allow mdio buses to auto-probe
> > > > c45 devices
> > > > 
> > > > From: Jeremy Linton <jeremy.linton@arm.com>
> > > > 
> > > > The mdiobus_scan logic is currently hardcoded to only
> > > > work with c22 devices. This works fairly well in most
> > > > cases, but its possible that a c45 device doesn't respond
> > > > despite being a standard phy. If the parent hardware
> > > > is capable, it makes sense to scan for c22 devices before
> > > > falling back to c45.
> > > > 
> > > > As we want this to reflect the capabilities of the STA,
> > > > lets add a field to the mii_bus structure to represent
> > > > the capability. That way devices can opt into the extended
> > > > scanning. Existing users should continue to default to c22
> > > > only scanning as long as they are zero'ing the structure
> > > > before use.
> > > 
> > > How is this default working for existing users, the code below does not seem
> > > to do anything for a zeroed struct, as there is no default in the switch?
> > 
> > Looking further into this, I think MDIOBUS_C22 = 0, was correct. Prior to
> > this patch, get_phy_device() was executed for C22 in this path. I'll discuss
> > with Russell and Andrew on this and get back.
> 
> It is not correct for the reasons I stated when I made the comment.
> When you introduce "probe_capabilities", every MDIO bus will have
> that field as zero.
> 
> In your original patch, that means the bus only supports clause 22.
> However, we have buses today that _that_ is factually incorrect.
> Therefore, introducing probe_capabilities with zero meaning MDIOBUS_C22
> is wrong.  It means we can _never_ assume that bus->probe_capabilities
> means the bus does not support Clause 45.
> 
> Now, as per your patch below, that is better.  It means we're able to
> identify those drivers that have not declared which bus access methods
> are supported, while we can positively identify those which have.
> 
> All that's needed is for your switch() statement to maintain today's
> behaviour where no declared probe_capabilities means that the bus
> should be probed for clause 22 PHYs.
> 
> This means we can later introduce the ability to prevent clause 45
> probing for PHYs that declare themselves as explicitly only supporting
> clause 22 if we need to without having been backed into a corner, and
> left wondering whether the lack of probe_capabilities is because someone
> decided "it's zero, so doesn't need to be initialised" and didn't bother
> explicitly stating .probe_capabilities = MDIOBUS_C22.

Got it. I'll add the MDIOBUS_NO_CAP case also.

Thanks
Calvin