[net-next] net: renesas: rswitch: cleanup max_speed setting

Commit Message

Nikita Yushchenko Feb. 3, 2025, 5:09 p.m. UTC

It was observed on spider board that with upstream kernel, PHY
auto-negotiation takes almost 1 second longer than with renesas BSP
kernel. This was tracked down to upstream kernel allowing more PHY modes
than renesas BSP kernel.

To avoid that effect when possible, always set max_speed to not more
than phy_interface allows.

While at this, also ensure that etha->speed always gets a supported
value, even if max_speed in device tree is set to something else.

Reported-by: Yoshihiro Shimoda <[e-mail]>
Signed-off-by: Nikita Yushchenko <[e-mail]>
---
 drivers/net/ethernet/renesas/rswitch.c | 48 ++++++++++++++------------
 drivers/net/ethernet/renesas/rswitch.h |  1 +
 2 files changed, 27 insertions(+), 22 deletions(-)

Comments

Andrew Lunn Feb. 3, 2025, 6:09 p.m. UTC | #1

On Mon, Feb 03, 2025 at 06:09:41PM +0100, Nikita Yushchenko wrote:
> It was observed on spider board that with upstream kernel, PHY
> auto-negotiation takes almost 1 second longer than with renesas BSP
> kernel. This was tracked down to upstream kernel allowing more PHY modes
> than renesas BSP kernel.
> 
> To avoid that effect when possible, always set max_speed to not more
> than phy_interface allows.

Please could you provide more information about the hardware. Is the
PHY more capable than the MAC?

When you have multi Gigi PHYs, the phy-mode is often taken to be the
starting point. But when the PHY has negotiated a link, it will tell
the MAC what PHY mode it needs to swap to, e.g from SGMII to
2500BaseX, etc.

You should only need max-speed when you have a PHY which can do more
than the MAC.

Also, phylink handles this a lot better than phylib. So you might want
to change rswitch to phylink, especially if you have link speeds > 1G.

	Andrew

Patch

diff --git a/drivers/net/ethernet/renesas/rswitch.c b/drivers/net/ethernet/renesas/rswitch.c
index 84d09a8973b7..4b4e174e3abb 100644
--- a/drivers/net/ethernet/renesas/rswitch.c
+++ b/drivers/net/ethernet/renesas/rswitch.c
@@ -1308,37 +1308,41 @@  static struct device_node *rswitch_get_port_node(struct rswitch_device *rdev)
 
 static int rswitch_etha_get_params(struct rswitch_device *rdev)
 {
-	u32 max_speed;
+	struct rswitch_etha *etha = rdev->etha;
 	int err;
 
 	if (!rdev->np_port)
 		return 0;	/* ignored */
 
-	err = of_get_phy_mode(rdev->np_port, &rdev->etha->phy_interface);
+	err = of_get_phy_mode(rdev->np_port, &etha->phy_interface);
 	if (err)
 		return err;
 
-	err = of_property_read_u32(rdev->np_port, "max-speed", &max_speed);
-	if (!err) {
-		rdev->etha->speed = max_speed;
-		return 0;
-	}
-
-	/* if no "max-speed" property, let's use default speed */
-	switch (rdev->etha->phy_interface) {
-	case PHY_INTERFACE_MODE_MII:
-		rdev->etha->speed = SPEED_100;
-		break;
+	switch (etha->phy_interface) {
 	case PHY_INTERFACE_MODE_SGMII:
-		rdev->etha->speed = SPEED_1000;
+		etha->max_speed = SPEED_1000;
 		break;
 	case PHY_INTERFACE_MODE_USXGMII:
-		rdev->etha->speed = SPEED_2500;
+	case PHY_INTERFACE_MODE_5GBASER:
+		etha->max_speed = SPEED_2500;
 		break;
 	default:
 		return -EINVAL;
 	}
 
+	/* Allow max_speed override */
+	of_property_read_u32(rdev->np_port, "max-speed", &etha->max_speed);
+
+	/* Set etha->speed to one of values expected by the driver */
+	if (etha->max_speed < SPEED_100)
+		return -EINVAL;
+	else if (etha->max_speed < SPEED_1000)
+		etha->speed = SPEED_100;
+	else if (etha->max_speed < SPEED_2500)
+		etha->speed = SPEED_1000;
+	else
+		etha->speed = SPEED_2500;
+
 	return 0;
 }
 
@@ -1412,6 +1416,13 @@  static void rswitch_adjust_link(struct net_device *ndev)
 static void rswitch_phy_remove_link_mode(struct rswitch_device *rdev,
 					 struct phy_device *phydev)
 {
+	phy_remove_link_mode(phydev, ETHTOOL_LINK_MODE_10baseT_Half_BIT);
+	phy_remove_link_mode(phydev, ETHTOOL_LINK_MODE_10baseT_Full_BIT);
+	phy_remove_link_mode(phydev, ETHTOOL_LINK_MODE_100baseT_Half_BIT);
+	phy_remove_link_mode(phydev, ETHTOOL_LINK_MODE_1000baseT_Half_BIT);
+
+	phy_set_max_speed(phydev, rdev->etha->max_speed);
+
 	if (!rdev->priv->etha_no_runtime_change)
 		return;
 
@@ -1431,8 +1442,6 @@  static void rswitch_phy_remove_link_mode(struct rswitch_device *rdev,
 	default:
 		break;
 	}
-
-	phy_set_max_speed(phydev, rdev->etha->speed);
 }
 
 static int rswitch_phy_device_init(struct rswitch_device *rdev)
@@ -1462,11 +1471,6 @@  static int rswitch_phy_device_init(struct rswitch_device *rdev)
 	if (!phydev)
 		goto out;
 
-	phy_set_max_speed(phydev, SPEED_2500);
-	phy_remove_link_mode(phydev, ETHTOOL_LINK_MODE_10baseT_Half_BIT);
-	phy_remove_link_mode(phydev, ETHTOOL_LINK_MODE_10baseT_Full_BIT);
-	phy_remove_link_mode(phydev, ETHTOOL_LINK_MODE_100baseT_Half_BIT);
-	phy_remove_link_mode(phydev, ETHTOOL_LINK_MODE_1000baseT_Half_BIT);
 	rswitch_phy_remove_link_mode(rdev, phydev);
 
 	phy_attached_info(phydev);
diff --git a/drivers/net/ethernet/renesas/rswitch.h b/drivers/net/ethernet/renesas/rswitch.h
index 532192cbca4b..09f5d5e1933e 100644
--- a/drivers/net/ethernet/renesas/rswitch.h
+++ b/drivers/net/ethernet/renesas/rswitch.h
@@ -920,6 +920,7 @@  struct rswitch_etha {
 	bool external_phy;
 	struct mii_bus *mii;
 	phy_interface_t phy_interface;
+	u32 max_speed;
 	u32 psmcs;
 	u8 mac_addr[MAX_ADDR_LEN];
 	int link;