[PATCH net-next v2 0/3] fix forced link mode for KSZ886X switches

[PATCH net-next v2 0/3] fix forced link mode for KSZ886X switches

[Oleksij Rempel]

changes v2:
- address kernel test robot warning
- change comment explaining clearing of KSZ886X_CTRL_FORCE_LINK bit
- s/PHY we create/PHY will create/

Oleksij Rempel (3):
  net: phy: micrel: Extend KSZ886X PHY Special Ctrl/Status Reg
    definitions
  net: dsa: microchip: ksz8: Enable MIIM PHY Control reg access
  net: phy: micrel: Fix forced link mode for KSZ886X switches

 drivers/net/dsa/microchip/ksz8795.c | 86 ++++++++++++++++++++++++++++-
 drivers/net/phy/micrel.c            | 32 ++++++++++-
 include/linux/micrel_phy.h          |  4 ++
 3 files changed, 116 insertions(+), 6 deletions(-)

-- 
2.39.2

[PATCH net-next v2 1/3] net: phy: micrel: Extend KSZ886X PHY Special Ctrl/Status Reg definitions

[Oleksij Rempel]

Extend 'micrel_phy.h' with additional definitions for KSZ886X PHY
Special Control/Status Register (Reg 31), for upcoming usage in
subsequent patches.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
---
 include/linux/micrel_phy.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/linux/micrel_phy.h b/include/linux/micrel_phy.h
index 4e27ca7c49de..591bf5b5e8dc 100644
--- a/include/linux/micrel_phy.h
+++ b/include/linux/micrel_phy.h
@@ -64,6 +64,10 @@
 #define KSZ886X_BMCR_DISABLE_TRANSMIT		BIT(1)
 #define KSZ886X_BMCR_DISABLE_LED		BIT(0)
 
+/* PHY Special Control/Status Register (Reg 31) */
 #define KSZ886X_CTRL_MDIX_STAT			BIT(4)
+#define KSZ886X_CTRL_FORCE_LINK			BIT(3)
+#define KSZ886X_CTRL_PWRSAVE			BIT(2)
+#define KSZ886X_CTRL_REMOTE_LOOPBACK		BIT(1)
 
 #endif /* _MICREL_PHY_H */
-- 
2.39.2

Re: [PATCH net-next v2 1/3] net: phy: micrel: Extend KSZ886X PHY Special Ctrl/Status Reg definitions

[Vladimir Oltean]

On Thu, Oct 12, 2023 at 08:55:00AM +0200, Oleksij Rempel wrote:
> Extend 'micrel_phy.h' with additional definitions for KSZ886X PHY
> Special Control/Status Register (Reg 31), for upcoming usage in
> subsequent patches.
> 
> Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
> ---

I think you can squash this into patch 2.

[PATCH net-next v2 2/3] net: dsa: microchip: ksz8: Enable MIIM PHY Control reg access

[Oleksij Rempel]

Provide access to MIIM PHY Control register (Reg. 31) through
ksz8_r_phy_ctrl() and ksz8_w_phy_ctrl() functions. Necessary for
upcoming micrel.c patch to address forced link mode configuration.

Closes: https://lore.kernel.org/oe-kbuild-all/202310112224.iYgvjBUy-lkp@intel.com/
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
---
 drivers/net/dsa/microchip/ksz8795.c | 86 ++++++++++++++++++++++++++++-
 1 file changed, 83 insertions(+), 3 deletions(-)

diff --git a/drivers/net/dsa/microchip/ksz8795.c b/drivers/net/dsa/microchip/ksz8795.c
index 91aba470fb2f..4bf4d67557dc 100644
--- a/drivers/net/dsa/microchip/ksz8795.c
+++ b/drivers/net/dsa/microchip/ksz8795.c
@@ -632,6 +632,50 @@ static void ksz8_w_vlan_table(struct ksz_device *dev, u16 vid, u16 vlan)
 	ksz8_w_table(dev, TABLE_VLAN, addr, buf);
 }
 
+/**
+ * ksz8_r_phy_ctrl - Translates and reads from the SMI interface to a MIIM PHY
+ *		     Control register (Reg. 31).
+ * @dev: The KSZ device instance.
+ * @port: The port number to be read.
+ * @val: The value read from the SMI interface.
+ *
+ * This function reads the SMI interface and translates the hardware register
+ * bit values into their corresponding control settings for a MIIM PHY Control
+ * register.
+ *
+ * Return: 0 on success, error code on failure.
+ */
+static int ksz8_r_phy_ctrl(struct ksz_device *dev, int port, u16 *val)
+{
+	const u16 *regs = dev->info->regs;
+	u8 reg_val;
+	int ret;
+
+	*val = 0;
+
+	ret = ksz_pread8(dev, port, regs[P_LINK_STATUS], &reg_val);
+	if (ret < 0)
+		return ret;
+
+	if (reg_val & PORT_MDIX_STATUS)
+		*val |= KSZ886X_CTRL_MDIX_STAT;
+
+	ret = ksz_pread8(dev, port, REG_PORT_LINK_MD_CTRL, &reg_val);
+	if (ret < 0)
+		return ret;
+
+	if (reg_val & PORT_FORCE_LINK)
+		*val |= KSZ886X_CTRL_FORCE_LINK;
+
+	if (reg_val & PORT_POWER_SAVING)
+		*val |= KSZ886X_CTRL_PWRSAVE;
+
+	if (reg_val & PORT_PHY_REMOTE_LOOPBACK)
+		*val |= KSZ886X_CTRL_REMOTE_LOOPBACK;
+
+	return 0;
+}
+
 int ksz8_r_phy(struct ksz_device *dev, u16 phy, u16 reg, u16 *val)
 {
 	u8 restart, speed, ctrl, link;
@@ -769,12 +813,10 @@ int ksz8_r_phy(struct ksz_device *dev, u16 phy, u16 reg, u16 *val)
 				FIELD_GET(PORT_CABLE_FAULT_COUNTER_L, val2));
 		break;
 	case PHY_REG_PHY_CTRL:
-		ret = ksz_pread8(dev, p, regs[P_LINK_STATUS], &link);
+		ret = ksz8_r_phy_ctrl(dev, p, &data);
 		if (ret)
 			return ret;
 
-		if (link & PORT_MDIX_STATUS)
-			data |= KSZ886X_CTRL_MDIX_STAT;
 		break;
 	default:
 		processed = false;
@@ -786,6 +828,38 @@ int ksz8_r_phy(struct ksz_device *dev, u16 phy, u16 reg, u16 *val)
 	return 0;
 }
 
+/**
+ * ksz8_w_phy_ctrl - Translates and writes to the SMI interface from a MIIM PHY
+ *		     Control register (Reg. 31).
+ * @dev: The KSZ device instance.
+ * @port: The port number to be configured.
+ * @val: The register value to be written.
+ *
+ * This function translates control settings from a MIIM PHY Control register
+ * into their corresponding hardware register bit values for the SMI
+ * interface.
+ *
+ * Return: 0 on success, error code on failure.
+ */
+static int ksz8_w_phy_ctrl(struct ksz_device *dev, int port, u16 val)
+{
+	u8 reg_val = 0;
+	int ret;
+
+	if (val & KSZ886X_CTRL_FORCE_LINK)
+		reg_val |= PORT_FORCE_LINK;
+
+	if (val & KSZ886X_CTRL_PWRSAVE)
+		reg_val |= PORT_POWER_SAVING;
+
+	if (val & KSZ886X_CTRL_REMOTE_LOOPBACK)
+		reg_val |= PORT_PHY_REMOTE_LOOPBACK;
+
+	ret = ksz_prmw8(dev, port, REG_PORT_LINK_MD_CTRL, PORT_FORCE_LINK |
+			PORT_POWER_SAVING | PORT_PHY_REMOTE_LOOPBACK, reg_val);
+	return ret;
+}
+
 int ksz8_w_phy(struct ksz_device *dev, u16 phy, u16 reg, u16 val)
 {
 	u8 restart, speed, ctrl, data;
@@ -926,6 +1000,12 @@ int ksz8_w_phy(struct ksz_device *dev, u16 phy, u16 reg, u16 val)
 		if (val & PHY_START_CABLE_DIAG)
 			ksz_port_cfg(dev, p, REG_PORT_LINK_MD_CTRL, PORT_START_CABLE_DIAG, true);
 		break;
+
+	case PHY_REG_PHY_CTRL:
+		ret = ksz8_w_phy_ctrl(dev, p, val);
+		if (ret)
+			return ret;
+		break;
 	default:
 		break;
 	}
-- 
2.39.2

[PATCH net-next v2 3/3] net: phy: micrel: Fix forced link mode for KSZ886X switches

[Oleksij Rempel]

Address a link speed detection issue in KSZ886X PHY driver when in
forced link mode. Previously, link partners like "ASIX AX88772B"
with KSZ8873 could fall back to 10Mbit instead of configured 100Mbit.

The issue arises as KSZ886X PHY continues sending Fast Link Pulses (FLPs)
even with autonegotiation off, misleading link partners in autoneg mode,
leading to incorrect link speed detection.

Now, when autonegotiation is disabled, the driver sets the link state
forcefully using KSZ886X_CTRL_FORCE_LINK bit. This action, beyond just
disabling autonegotiation, makes the PHY state more reliably detected by
link partners using parallel detection, thus fixing the link speed
misconfiguration.

With autonegotiation enabled, link state is not forced, allowing proper
autonegotiation process participation.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
---
 drivers/net/phy/micrel.c | 32 +++++++++++++++++++++++++++++---
 1 file changed, 29 insertions(+), 3 deletions(-)

diff --git a/drivers/net/phy/micrel.c b/drivers/net/phy/micrel.c
index 927d3d54658e..599ebf54fafe 100644
--- a/drivers/net/phy/micrel.c
+++ b/drivers/net/phy/micrel.c
@@ -1729,9 +1729,35 @@ static int ksz886x_config_aneg(struct phy_device *phydev)
 {
 	int ret;
 
-	ret = genphy_config_aneg(phydev);
-	if (ret)
-		return ret;
+	if (phydev->autoneg != AUTONEG_ENABLE) {
+		ret = genphy_setup_forced(phydev);
+		if (ret)
+			return ret;
+
+		/* When autonegotation is disabled, we need to manually force
+		 * the link state. If we don't do this, the PHY will keep
+		 * sending Fast Link Pulses (FLPs) which are part of the
+		 * autonegotiation process. This is not desired when
+		 * autonegotiation is off.
+		 */
+		ret = phy_set_bits(phydev, MII_KSZPHY_CTRL,
+				   KSZ886X_CTRL_FORCE_LINK);
+		if (ret)
+			return ret;
+	} else {
+		/* If we had previously forced the link state, we need to
+		 * clear KSZ886X_CTRL_FORCE_LINK bit now. Otherwise, the PHY
+		 * will not perform autonegotiation.
+		 */
+		ret = phy_clear_bits(phydev, MII_KSZPHY_CTRL,
+				     KSZ886X_CTRL_FORCE_LINK);
+		if (ret)
+			return ret;
+
+		ret = genphy_config_aneg(phydev);
+		if (ret)
+			return ret;
+	}
 
 	/* The MDI-X configuration is automatically changed by the PHY after
 	 * switching from autoneg off to on. So, take MDI-X configuration under
-- 
2.39.2

Re: [PATCH net-next v2 3/3] net: phy: micrel: Fix forced link mode for KSZ886X switches

[Vladimir Oltean]

Hi Oleksij,

On Thu, Oct 12, 2023 at 08:55:02AM +0200, Oleksij Rempel wrote:
> Address a link speed detection issue in KSZ886X PHY driver when in
> forced link mode. Previously, link partners like "ASIX AX88772B"
> with KSZ8873 could fall back to 10Mbit instead of configured 100Mbit.
> 
> The issue arises as KSZ886X PHY continues sending Fast Link Pulses (FLPs)
> even with autonegotiation off, misleading link partners in autoneg mode,
> leading to incorrect link speed detection.
> 
> Now, when autonegotiation is disabled, the driver sets the link state
> forcefully using KSZ886X_CTRL_FORCE_LINK bit. This action, beyond just
> disabling autonegotiation, makes the PHY state more reliably detected by
> link partners using parallel detection, thus fixing the link speed
> misconfiguration.
> 
> With autonegotiation enabled, link state is not forced, allowing proper
> autonegotiation process participation.
> 
> Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
> ---

Have you considered denying "ethtool -s swpN autoneg off" in "net.git"
(considering that it doesn't work properly), and re-enabling it in
"net-next.git"?

>  drivers/net/phy/micrel.c | 32 +++++++++++++++++++++++++++++---
>  1 file changed, 29 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/phy/micrel.c b/drivers/net/phy/micrel.c
> index 927d3d54658e..599ebf54fafe 100644
> --- a/drivers/net/phy/micrel.c
> +++ b/drivers/net/phy/micrel.c
> @@ -1729,9 +1729,35 @@ static int ksz886x_config_aneg(struct phy_device *phydev)
>  {
>  	int ret;
>  
> -	ret = genphy_config_aneg(phydev);
> -	if (ret)
> -		return ret;
> +	if (phydev->autoneg != AUTONEG_ENABLE) {
> +		ret = genphy_setup_forced(phydev);
> +		if (ret)
> +			return ret;

__genphy_config_aneg() will call genphy_setup_forced() as appropriate,
and additionally it will resync the master-slave resolution to a forced
value, if needed. So I think it's better to call genphy_config_aneg()
from the common code path, and just use the "if (phydev->autoneg)" test
to keep the vendor-specific register in sync with the autoneg setting.

> +
> +		/* When autonegotation is disabled, we need to manually force
> +		 * the link state. If we don't do this, the PHY will keep
> +		 * sending Fast Link Pulses (FLPs) which are part of the
> +		 * autonegotiation process. This is not desired when
> +		 * autonegotiation is off.
> +		 */
> +		ret = phy_set_bits(phydev, MII_KSZPHY_CTRL,
> +				   KSZ886X_CTRL_FORCE_LINK);
> +		if (ret)
> +			return ret;
> +	} else {
> +		/* If we had previously forced the link state, we need to
> +		 * clear KSZ886X_CTRL_FORCE_LINK bit now. Otherwise, the PHY
> +		 * will not perform autonegotiation.
> +		 */
> +		ret = phy_clear_bits(phydev, MII_KSZPHY_CTRL,
> +				     KSZ886X_CTRL_FORCE_LINK);
> +		if (ret)
> +			return ret;
> +
> +		ret = genphy_config_aneg(phydev);
> +		if (ret)
> +			return ret;
> +	}
>  
>  	/* The MDI-X configuration is automatically changed by the PHY after
>  	 * switching from autoneg off to on. So, take MDI-X configuration under
> -- 
> 2.39.2
> 

Re: [PATCH net-next v2 3/3] net: phy: micrel: Fix forced link mode for KSZ886X switches

[Oleksij Rempel]

Hi Vladimir,

On Fri, Oct 13, 2023 at 03:26:46PM +0300, Vladimir Oltean wrote:
> Hi Oleksij,
> 
> On Thu, Oct 12, 2023 at 08:55:02AM +0200, Oleksij Rempel wrote:
> > Address a link speed detection issue in KSZ886X PHY driver when in
> > forced link mode. Previously, link partners like "ASIX AX88772B"
> > with KSZ8873 could fall back to 10Mbit instead of configured 100Mbit.
> > 
> > The issue arises as KSZ886X PHY continues sending Fast Link Pulses (FLPs)
> > even with autonegotiation off, misleading link partners in autoneg mode,
> > leading to incorrect link speed detection.
> > 
> > Now, when autonegotiation is disabled, the driver sets the link state
> > forcefully using KSZ886X_CTRL_FORCE_LINK bit. This action, beyond just
> > disabling autonegotiation, makes the PHY state more reliably detected by
> > link partners using parallel detection, thus fixing the link speed
> > misconfiguration.
> > 
> > With autonegotiation enabled, link state is not forced, allowing proper
> > autonegotiation process participation.
> > 
> > Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
> > ---
> 
> Have you considered denying "ethtool -s swpN autoneg off" in "net.git"
> (considering that it doesn't work properly), and re-enabling it in
> "net-next.git"?

Yes, but for ksz8 task I don't have budget to go this way.

> >  drivers/net/phy/micrel.c | 32 +++++++++++++++++++++++++++++---
> >  1 file changed, 29 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/net/phy/micrel.c b/drivers/net/phy/micrel.c
> > index 927d3d54658e..599ebf54fafe 100644
> > --- a/drivers/net/phy/micrel.c
> > +++ b/drivers/net/phy/micrel.c
> > @@ -1729,9 +1729,35 @@ static int ksz886x_config_aneg(struct phy_device *phydev)
> >  {
> >  	int ret;
> >  
> > -	ret = genphy_config_aneg(phydev);
> > -	if (ret)
> > -		return ret;
> > +	if (phydev->autoneg != AUTONEG_ENABLE) {
> > +		ret = genphy_setup_forced(phydev);
> > +		if (ret)
> > +			return ret;
> 
> __genphy_config_aneg() will call genphy_setup_forced() as appropriate,
> and additionally it will resync the master-slave resolution to a forced
> value, if needed. So I think it's better to call genphy_config_aneg()
> from the common code path, and just use the "if (phydev->autoneg)" test
> to keep the vendor-specific register in sync with the autoneg setting.

ack. Will update it.

Regards,
Oleksij
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