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

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Date:   Mon, 22 Jun 2020 13:49:12 +0530
From:   Calvin Johnson <calvin.johnson@....nxp.com>
To:     Jeremy Linton <jeremy.linton@....com>,
        Russell King - ARM Linux admin <linux@...linux.org.uk>,
        Jon <jon@...id-run.com>,
        Cristi Sovaiala <cristian.sovaiala@....com>,
        Ioana Ciornei <ioana.ciornei@....com>,
        Andrew Lunn <andrew@...n.ch>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Madalin Bucur <madalin.bucur@....nxp.com>
Cc:     linux.cj@...il.com, netdev@...r.kernel.org,
        Calvin Johnson <calvin.johnson@....nxp.com>
Subject: [net-next PATCH v2 1/3] net: phy: Allow mdio buses to auto-probe c45 devices

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