On 7/19/22 1:26 PM, Vladimir Oltean wrote:

On Mon, Jul 11, 2022 at 12:05:15PM -0400, Sean Anderson wrote:

quoted

There is a common flow in several drivers where a lynx PCS is created
without a corresponding firmware node. Consolidate these into one helper
function. Because we control when the mdiodev is registered, we can add
a custom match function which will automatically bind our driver
(instead of using device_driver_attach).

Signed-off-by: Sean Anderson <redacted>
---

 drivers/net/dsa/ocelot/felix_vsc9959.c        | 25 ++++---------------
 drivers/net/dsa/ocelot/seville_vsc9953.c      | 25 ++++---------------
 .../net/ethernet/freescale/enetc/enetc_pf.c   | 21 +++-------------
 drivers/net/pcs/pcs-lynx.c                    | 24 ++++++++++++++++++
 include/linux/pcs-lynx.h                      |  1 +
 5 files changed, 39 insertions(+), 57 deletions(-)

diff --git a/drivers/net/dsa/ocelot/felix_vsc9959.c b/drivers/net/dsa/ocelot/felix_vsc9959.c
index 57634e2296c0..0a756c25d5e8 100644
--- a/drivers/net/dsa/ocelot/felix_vsc9959.c
+++ b/drivers/net/dsa/ocelot/felix_vsc9959.c

@@ -11,6 +11,7 @@
 #include <net/tc_act/tc_gate.h>
 #include <soc/mscc/ocelot.h>
 #include <linux/dsa/ocelot.h>
+#include <linux/pcs.h>
 #include <linux/pcs-lynx.h>
 #include <net/pkt_sched.h>
 #include <linux/iopoll.h>

@@ -1089,16 +1090,9 @@ static int vsc9959_mdio_bus_alloc(struct ocelot *ocelot)
 		if (ocelot_port->phy_mode == PHY_INTERFACE_MODE_INTERNAL)
 			continue;
 
-		mdio_device = mdio_device_create(felix->imdio, port);
-		if (IS_ERR(mdio_device))
+		phylink_pcs = lynx_pcs_create_on_bus(felix->imdio, port);
+		if (IS_ERR(phylink_pcs))
 			continue;
-
-		phylink_pcs = lynx_pcs_create(mdio_device);
-		if (IS_ERR(phylink_pcs)) {
-			mdio_device_free(mdio_device);
-			continue;
-		}
-
 		felix->pcs[port] = phylink_pcs;
 
 		dev_info(dev, "Found PCS at internal MDIO address %d\n", port);

@@ -1112,17 +1106,8 @@ static void vsc9959_mdio_bus_free(struct ocelot *ocelot)
 	struct felix *felix = ocelot_to_felix(ocelot);
 	int port;
 
-	for (port = 0; port < ocelot->num_phys_ports; port++) {
-		struct phylink_pcs *phylink_pcs = felix->pcs[port];
-		struct mdio_device *mdio_device;
-
-		if (!phylink_pcs)
-			continue;
-
-		mdio_device = lynx_get_mdio_device(phylink_pcs);
-		mdio_device_free(mdio_device);
-		lynx_pcs_destroy(phylink_pcs);
-	}
+	for (port = 0; port < ocelot->num_phys_ports; port++)
+		pcs_put(felix->pcs[port]);
 	mdiobus_unregister(felix->imdio);
 	mdiobus_free(felix->imdio);
 }

diff --git a/drivers/net/dsa/ocelot/seville_vsc9953.c b/drivers/net/dsa/ocelot/seville_vsc9953.c
index 8c52de5d0b02..9006dec85ef0 100644
--- a/drivers/net/dsa/ocelot/seville_vsc9953.c
+++ b/drivers/net/dsa/ocelot/seville_vsc9953.c

@@ -9,6 +9,7 @@
 #include <linux/mdio/mdio-mscc-miim.h>
 #include <linux/of_mdio.h>
 #include <linux/of_platform.h>
+#include <linux/pcs.h>
 #include <linux/pcs-lynx.h>
 #include <linux/dsa/ocelot.h>
 #include <linux/iopoll.h>

@@ -1044,16 +1045,9 @@ static int vsc9953_mdio_bus_alloc(struct ocelot *ocelot)
 		if (ocelot_port->phy_mode == PHY_INTERFACE_MODE_INTERNAL)
 			continue;
 
-		mdio_device = mdio_device_create(felix->imdio, addr);
-		if (IS_ERR(mdio_device))
+		phylink_pcs = lynx_pcs_create_on_bus(felix->imdio, addr);
+		if (IS_ERR(phylink_pcs))
 			continue;
-
-		phylink_pcs = lynx_pcs_create(mdio_device);
-		if (IS_ERR(phylink_pcs)) {
-			mdio_device_free(mdio_device);
-			continue;
-		}
-
 		felix->pcs[port] = phylink_pcs;
 
 		dev_info(dev, "Found PCS at internal MDIO address %d\n", addr);

@@ -1067,17 +1061,8 @@ static void vsc9953_mdio_bus_free(struct ocelot *ocelot)
 	struct felix *felix = ocelot_to_felix(ocelot);
 	int port;
 
-	for (port = 0; port < ocelot->num_phys_ports; port++) {
-		struct phylink_pcs *phylink_pcs = felix->pcs[port];
-		struct mdio_device *mdio_device;
-
-		if (!phylink_pcs)
-			continue;
-
-		mdio_device = lynx_get_mdio_device(phylink_pcs);
-		mdio_device_free(mdio_device);
-		lynx_pcs_destroy(phylink_pcs);
-	}
+	for (port = 0; port < ocelot->num_phys_ports; port++)
+		pcs_put(felix->pcs[port]);
 
 	/* mdiobus_unregister and mdiobus_free handled by devres */
 }

diff --git a/drivers/net/ethernet/freescale/enetc/enetc_pf.c b/drivers/net/ethernet/freescale/enetc/enetc_pf.c
index 8c923a93da88..8da7c8644e44 100644
--- a/drivers/net/ethernet/freescale/enetc/enetc_pf.c
+++ b/drivers/net/ethernet/freescale/enetc/enetc_pf.c

@@ -8,6 +8,7 @@
 #include <linux/of_platform.h>
 #include <linux/of_mdio.h>
 #include <linux/of_net.h>
+#include <linux/pcs.h>
 #include <linux/pcs-lynx.h>
 #include "enetc_ierb.h"
 #include "enetc_pf.h"

@@ -827,7 +828,6 @@ static int enetc_imdio_create(struct enetc_pf *pf)
 	struct device *dev = &pf->si->pdev->dev;
 	struct enetc_mdio_priv *mdio_priv;
 	struct phylink_pcs *phylink_pcs;
-	struct mdio_device *mdio_device;
 	struct mii_bus *bus;
 	int err;
 

@@ -851,16 +851,8 @@ static int enetc_imdio_create(struct enetc_pf *pf)
 		goto free_mdio_bus;
 	}
 
-	mdio_device = mdio_device_create(bus, 0);
-	if (IS_ERR(mdio_device)) {
-		err = PTR_ERR(mdio_device);
-		dev_err(dev, "cannot create mdio device (%d)\n", err);
-		goto unregister_mdiobus;
-	}
-
-	phylink_pcs = lynx_pcs_create(mdio_device);
+	phylink_pcs = lynx_pcs_create_on_bus(bus, 0);
 	if (IS_ERR(phylink_pcs)) {
-		mdio_device_free(mdio_device);
 		err = PTR_ERR(phylink_pcs);
 		dev_err(dev, "cannot create lynx pcs (%d)\n", err);
 		goto unregister_mdiobus;

@@ -880,13 +872,8 @@ static int enetc_imdio_create(struct enetc_pf *pf)
 
 static void enetc_imdio_remove(struct enetc_pf *pf)
 {
-	struct mdio_device *mdio_device;
-
-	if (pf->pcs) {
-		mdio_device = lynx_get_mdio_device(pf->pcs);
-		mdio_device_free(mdio_device);
-		lynx_pcs_destroy(pf->pcs);
-	}
+	if (pf->pcs)
+		pcs_put(pf->pcs);
 	if (pf->imdio) {
 		mdiobus_unregister(pf->imdio);
 		mdiobus_free(pf->imdio);

diff --git a/drivers/net/pcs/pcs-lynx.c b/drivers/net/pcs/pcs-lynx.c
index 8272072698e4..adb9fd5ce72e 100644
--- a/drivers/net/pcs/pcs-lynx.c
+++ b/drivers/net/pcs/pcs-lynx.c

@@ -403,6 +403,30 @@ struct phylink_pcs *lynx_pcs_create(struct mdio_device *mdio)
 }
 EXPORT_SYMBOL(lynx_pcs_create);
 
+struct phylink_pcs *lynx_pcs_create_on_bus(struct mii_bus *bus, int addr)
+{
+	struct mdio_device *mdio;
+	struct phylink_pcs *pcs;
+	int err;
+
+	mdio = mdio_device_create(bus, addr);
+	if (IS_ERR(mdio))
+		return ERR_CAST(mdio);
+
+	mdio->bus_match = mdio_device_bus_match;
+	strncpy(mdio->modalias, "lynx-pcs", sizeof(mdio->modalias));
+	err = mdio_device_register(mdio);

Yeah, so the reason why mdio_device_register() fails with -EBUSY for the
PCS devices created by felix_vsc9959.c is this:

int mdiobus_register_device(struct mdio_device *mdiodev)
{
	int err;

	if (mdiodev->bus->mdio_map[mdiodev->addr])
		return -EBUSY;

In other words, we already have an existing mdiodev on the bus at
address mdiodev->addr. Funnily enough, that device is actually us.
It was created at MDIO bus creation time, a dummy phydev that no one
connects to, found by mdiobus_scan(). I knew this was taking place,
but forgot/didn't realize the connection with this patch set, and that
dummy phy_device was completely harmless until now.

I can suppress its creation like this:

From b1d1cd1625a27a62fd02598c7015b8ff0afdd28a Mon Sep 17 00:00:00 2001
From: Vladimir Oltean <vladimir.oltean@nxp.com>
Date: Tue, 19 Jul 2022 20:15:52 +0300
Subject: [PATCH] net: dsa: ocelot: suppress PHY device scanning on the
 internal MDIO bus

This bus contains Lynx PCS devices, and if the lynx-pcs driver ever
decided to call mdio_device_register(), it would fail due to
mdiobus_scan() having created a dummy phydev for the same address
(the PCS responds to standard clause 22 PHY ID registers and can
therefore by autodetected by phylib which thinks it's a PHY).

On the Seville driver, things are a bit more complicated, since bus
creation is handled by mscc_miim_setup() and that is shared with the
dedicated mscc-miim driver. Suppress PHY scanning only for the Seville
internal MDIO bus rather than for the whole mscc-miim driver, since we
know that on NXP T1040, this bus only contains Lynx PCS devices.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
---
 drivers/net/dsa/ocelot/felix_vsc9959.c   | 4 ++++
 drivers/net/dsa/ocelot/seville_vsc9953.c | 6 +++++-
 2 files changed, 9 insertions(+), 1 deletion(-)

Thanks! I'll pick this up for v2.

--Sean