[PATCH v5 net 0/4] Fix broken link on Xilinx's AXI Ethernet in SGMII mode

[PATCH v5 net 0/4] Fix broken link on Xilinx's AXI Ethernet in SGMII mode

[Andy Chiu]

The Ethernet driver use phy-handle to reference the PCS/PMA PHY. This
could be a problem if one wants to configure an external PHY via phylink,
since it use the same phandle to get the PHY. To fix this, introduce a
dedicated pcs-handle to point to the PCS/PMA PHY and deprecate the use
of pointing it with phy-handle. A similar use case of pcs-handle can be
seen on dpaa2 as well.

The v4 patch was wrongly based on net-next tree. 1,2,4 parts of v5 patch
was generated after re-applying the v4 patch then resolving conflicts on
the net tree. 3/5 also describes the pcs-handle more globally at the
ethernet-controller device tree binding document.

Andy Chiu (4):
  net: axienet: setup mdio unconditionally
  net: axienet: factor out phy_node in struct axienet_local
  dt-bindings: net: add pcs-handle attribute
  net: axiemac: use a phandle to reference pcs_phy

 .../bindings/net/ethernet-controller.yaml     |  6 ++++
 .../bindings/net/xilinx_axienet.txt           |  8 ++++-
 drivers/net/ethernet/xilinx/xilinx_axienet.h  |  2 --
 .../net/ethernet/xilinx/xilinx_axienet_main.c | 33 ++++++++++---------
 4 files changed, 31 insertions(+), 18 deletions(-)

-- 
2.34.1

[PATCH v5 net 1/4] net: axienet: setup mdio unconditionally

[Andy Chiu]

The call to axienet_mdio_setup should not depend on whether "phy-node"
pressents on the DT. Besides, since `lp->phy_node` is used if PHY is in
SGMII or 100Base-X modes, move it into the if statement. And the next patch
will remove `lp->phy_node` from driver's private structure and do an
of_node_put on it right away after use since it is not used elsewhere.

Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
Reviewed-by: Greentime Hu <greentime.hu@sifive.com>
Reviewed-by: Robert Hancock <robert.hancock@calian.com>
---
 drivers/net/ethernet/xilinx/xilinx_axienet_main.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
index 377c94ec2486..93be1adc303f 100644
--- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
+++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
@@ -2060,15 +2060,14 @@ static int axienet_probe(struct platform_device *pdev)
 	if (ret)
 		goto cleanup_clk;
 
-	lp->phy_node = of_parse_phandle(pdev->dev.of_node, "phy-handle", 0);
-	if (lp->phy_node) {
-		ret = axienet_mdio_setup(lp);
-		if (ret)
-			dev_warn(&pdev->dev,
-				 "error registering MDIO bus: %d\n", ret);
-	}
+	ret = axienet_mdio_setup(lp);
+	if (ret)
+		dev_warn(&pdev->dev,
+			 "error registering MDIO bus: %d\n", ret);
+
 	if (lp->phy_mode == PHY_INTERFACE_MODE_SGMII ||
 	    lp->phy_mode == PHY_INTERFACE_MODE_1000BASEX) {
+		lp->phy_node = of_parse_phandle(pdev->dev.of_node, "phy-handle", 0);
 		if (!lp->phy_node) {
 			dev_err(&pdev->dev, "phy-handle required for 1000BaseX/SGMII\n");
 			ret = -EINVAL;
-- 
2.34.1

[PATCH v5 net 2/4] net: axienet: factor out phy_node in struct axienet_local

[Andy Chiu]

the struct member `phy_node` of struct axienet_local is not used by the
driver anymore after initialization. It might be a remnent of old code
and could be removed.

Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
Reviewed-by: Greentime Hu <greentime.hu@sifive.com>
Reviewed-by: Robert Hancock <robert.hancock@calian.com>
---
 drivers/net/ethernet/xilinx/xilinx_axienet.h      |  2 --
 drivers/net/ethernet/xilinx/xilinx_axienet_main.c | 13 +++++--------
 2 files changed, 5 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet.h b/drivers/net/ethernet/xilinx/xilinx_axienet.h
index 5b4d153b1492..6a0b7ad958cd 100644
--- a/drivers/net/ethernet/xilinx/xilinx_axienet.h
+++ b/drivers/net/ethernet/xilinx/xilinx_axienet.h
@@ -428,8 +428,6 @@ struct axienet_local {
 	struct net_device *ndev;
 	struct device *dev;
 
-	struct device_node *phy_node;
-
 	struct phylink *phylink;
 	struct phylink_config phylink_config;
 
diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
index 93be1adc303f..a4783f95b979 100644
--- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
+++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
@@ -2067,18 +2067,20 @@ static int axienet_probe(struct platform_device *pdev)
 
 	if (lp->phy_mode == PHY_INTERFACE_MODE_SGMII ||
 	    lp->phy_mode == PHY_INTERFACE_MODE_1000BASEX) {
-		lp->phy_node = of_parse_phandle(pdev->dev.of_node, "phy-handle", 0);
-		if (!lp->phy_node) {
+		np = of_parse_phandle(pdev->dev.of_node, "phy-handle", 0);
+		if (!np) {
 			dev_err(&pdev->dev, "phy-handle required for 1000BaseX/SGMII\n");
 			ret = -EINVAL;
 			goto cleanup_mdio;
 		}
-		lp->pcs_phy = of_mdio_find_device(lp->phy_node);
+		lp->pcs_phy = of_mdio_find_device(np);
 		if (!lp->pcs_phy) {
 			ret = -EPROBE_DEFER;
+			of_node_put(np);
 			goto cleanup_mdio;
 		}
 		lp->phylink_config.pcs_poll = true;
+		of_node_put(np);
 	}
 
 	lp->phylink_config.dev = &ndev->dev;
@@ -2120,8 +2122,6 @@ static int axienet_probe(struct platform_device *pdev)
 		put_device(&lp->pcs_phy->dev);
 	if (lp->mii_bus)
 		axienet_mdio_teardown(lp);
-	of_node_put(lp->phy_node);
-
 cleanup_clk:
 	clk_bulk_disable_unprepare(XAE_NUM_MISC_CLOCKS, lp->misc_clks);
 	clk_disable_unprepare(lp->axi_clk);
@@ -2150,9 +2150,6 @@ static int axienet_remove(struct platform_device *pdev)
 	clk_bulk_disable_unprepare(XAE_NUM_MISC_CLOCKS, lp->misc_clks);
 	clk_disable_unprepare(lp->axi_clk);
 
-	of_node_put(lp->phy_node);
-	lp->phy_node = NULL;
-
 	free_netdev(ndev);
 
 	return 0;
-- 
2.34.1

[PATCH v5 net 3/4] dt-bindings: net: add pcs-handle attribute

[Andy Chiu]

Document the new pcs-handle attribute to support connecting to an
external PHY. For Xilinx's AXI Ethernet, this is used when the core
operates in SGMII or 1000Base-X modes and links through the internal
PCS/PMA PHY.

Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
Reviewed-by: Greentime Hu <greentime.hu@sifive.com>
---
 .../devicetree/bindings/net/ethernet-controller.yaml      | 6 ++++++
 Documentation/devicetree/bindings/net/xilinx_axienet.txt  | 8 +++++++-
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/net/ethernet-controller.yaml b/Documentation/devicetree/bindings/net/ethernet-controller.yaml
index 34c5463abcec..978772c04e1c 100644
--- a/Documentation/devicetree/bindings/net/ethernet-controller.yaml
+++ b/Documentation/devicetree/bindings/net/ethernet-controller.yaml
@@ -102,6 +102,12 @@ properties:
   phy-mode:
     $ref: "#/properties/phy-connection-type"
 
+  pcs-handle:
+    $ref: /schemas/types.yaml#/definitions/phandle
+    description:
+      Specifies a reference to a node representing a PCS PHY device on a MDIO
+      bus to link with an external PHY (phy-handle) if exists.
+
   phy-handle:
     $ref: /schemas/types.yaml#/definitions/phandle
     description:
diff --git a/Documentation/devicetree/bindings/net/xilinx_axienet.txt b/Documentation/devicetree/bindings/net/xilinx_axienet.txt
index b8e4894bc634..ba720a2ea5fc 100644
--- a/Documentation/devicetree/bindings/net/xilinx_axienet.txt
+++ b/Documentation/devicetree/bindings/net/xilinx_axienet.txt
@@ -26,7 +26,8 @@ Required properties:
 		  specified, the TX/RX DMA interrupts should be on that node
 		  instead, and only the Ethernet core interrupt is optionally
 		  specified here.
-- phy-handle	: Should point to the external phy device.
+- phy-handle	: Should point to the external phy device if exists. Pointing
+		  this to the PCS/PMA PHY is deprecated and should be avoided.
 		  See ethernet.txt file in the same directory.
 - xlnx,rxmem	: Set to allocated memory buffer for Rx/Tx in the hardware
 
@@ -68,6 +69,11 @@ Optional properties:
 		  required through the core's MDIO interface (i.e. always,
 		  unless the PHY is accessed through a different bus).
 
+ - pcs-handle: 	  Phandle to the internal PCS/PMA PHY in SGMII or 1000Base-X
+		  modes, where "pcs-handle" should be preferably used to point
+		  to the PCS/PMA PHY, and "phy-handle" should point to an
+		  external PHY if exists.
+
 Example:
 	axi_ethernet_eth: ethernet@40c00000 {
 		compatible = "xlnx,axi-ethernet-1.00.a";
-- 
2.34.1

Re: [PATCH v5 net 3/4] dt-bindings: net: add pcs-handle attribute

[Andrew Lunn]

> + - pcs-handle: 	  Phandle to the internal PCS/PMA PHY in SGMII or 1000Base-X
> +		  modes, where "pcs-handle" should be preferably used to point
> +		  to the PCS/PMA PHY, and "phy-handle" should point to an
> +		  external PHY if exists.

Since this is a new property, you don't have any backwards
compatibility to worry about, don't use 'preferably'. It should point
to the PCS/PCA PHY and anything else is wrong for this new property.

   Andrew

Re: [PATCH v5 net 3/4] dt-bindings: net: add pcs-handle attribute

[Andy Chiu]

Thanks for the suggestion. I have included this in the v6 patch.

Andy


On Sat, Mar 26, 2022 at 3:23 AM Andrew Lunn <andrew@lunn.ch> wrote:
>
> > + - pcs-handle:         Phandle to the internal PCS/PMA PHY in SGMII or 1000Base-X
> > +               modes, where "pcs-handle" should be preferably used to point
> > +               to the PCS/PMA PHY, and "phy-handle" should point to an
> > +               external PHY if exists.
>
> Since this is a new property, you don't have any backwards
> compatibility to worry about, don't use 'preferably'. It should point
> to the PCS/PCA PHY and anything else is wrong for this new property.
>
>    Andrew

[PATCH v5 net 4/4] net: axiemac: use a phandle to reference pcs_phy

[Andy Chiu]

In some SGMII use cases where both a fixed link external PHY and the
internal PCS/PMA PHY need to be configured, we should explicitly use a
phandle "pcs-phy" to get the reference to the PCS/PMA PHY. Otherwise, the
driver would use "phy-handle" in the DT as the reference to both the
external and the internal PCS/PMA PHY.

In other cases where the core is connected to a SFP cage, we could still
point phy-handle to the intenal PCS/PMA PHY, and let the driver connect
to the SFP module, if exist, via phylink.

Fixes: 1a02556086fc (net: axienet: Properly handle PCS/PMA PHY for 1000BaseX mode)
Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
Reviewed-by: Greentime Hu <greentime.hu@sifive.com>
Reviewed-by: Robert Hancock <robert.hancock@calian.com>
---
 drivers/net/ethernet/xilinx/xilinx_axienet_main.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
index a4783f95b979..6749d0eebc13 100644
--- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
+++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
@@ -2067,9 +2067,16 @@ static int axienet_probe(struct platform_device *pdev)
 
 	if (lp->phy_mode == PHY_INTERFACE_MODE_SGMII ||
 	    lp->phy_mode == PHY_INTERFACE_MODE_1000BASEX) {
-		np = of_parse_phandle(pdev->dev.of_node, "phy-handle", 0);
+		np = of_parse_phandle(pdev->dev.of_node, "pcs-handle", 0);
 		if (!np) {
-			dev_err(&pdev->dev, "phy-handle required for 1000BaseX/SGMII\n");
+			/* Deprecated: Always use "pcs-handle" for pcs_phy.
+			 * Falling back to "phy-handle" here is only for
+			 * backward compatibility with old device trees.
+			 */
+			np = of_parse_phandle(pdev->dev.of_node, "phy-handle", 0);
+		}
+		if (!np) {
+			dev_err(&pdev->dev, "pcs-handle (preferred) or phy-handle required for 1000BaseX/SGMII\n");
 			ret = -EINVAL;
 			goto cleanup_mdio;
 		}
-- 
2.34.1