Commit 9e62bed6 authored by Oleksij Rempel's avatar Oleksij Rempel Committed by Jakub Kicinski
Browse files

net: dsa: microchip: implement PHY loopback configuration for KSZ8794 and KSZ8873 



Correct the PHY loopback bit handling in the ksz8_w_phy_bmcr and
ksz8_r_phy_bmcr functions for KSZ8794 and KSZ8873 variants in the ksz8795
driver. Previously, the code erroneously used Bit 7 of port register 0xD
for both chip variants, which is actually for LED configuration. This
update ensures the correct registers and bits are used for the PHY
loopback feature:

- For KSZ8794: Use 0xF / Bit 7.
- For KSZ8873: Use 0xD / Bit 0.

The lack of loopback support was seen on KSZ8873 system by using
"ethtool -t lanX". After this patch, the ethtool selftest will work,
but only if port is not part of a bridge.

Signed-off-by: default avatarOleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: default avatarVladimir Oltean <vladimir.oltean@nxp.com>
Acked-by: default avatarArun Ramadoss <arun.ramadoss@microchip.com>
Link: https://lore.kernel.org/r/20240124123314.734815-4-o.rempel@pengutronix.de


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent d1b7d0d8

drivers/net/dsa/microchip/ksz8795.c

+69 −7
Original line number Diff line number Diff line
@@ -632,6 +632,57 @@ static void ksz8_w_vlan_table(struct ksz_device *dev, u16 vid, u16 vlan) 
	ksz8_w_table(dev, TABLE_VLAN, addr, buf);

}



/**

 * ksz879x_get_loopback - KSZ879x specific function to get loopback

 *                        configuration status for a specific port

 * @dev: Pointer to the device structure

 * @port: Port number to query

 * @val: Pointer to store the result

 *

 * This function reads the SMI registers to determine whether loopback mode

 * is enabled for a specific port.

 *

 * Return: 0 on success, error code on failure.

 */

static int ksz879x_get_loopback(struct ksz_device *dev, u16 port,

				u16 *val)

{

	u8 stat3;

	int ret;



	ret = ksz_pread8(dev, port, REG_PORT_STATUS_3, &stat3);

	if (ret)

		return ret;



	if (stat3 & PORT_PHY_LOOPBACK)

		*val |= BMCR_LOOPBACK;



	return 0;

}



/**

 * ksz879x_set_loopback - KSZ879x specific function  to set loopback mode for

 *			  a specific port

 * @dev: Pointer to the device structure.

 * @port: Port number to modify.

 * @val: Value indicating whether to enable or disable loopback mode.

 *

 * This function translates loopback bit of the BMCR register into the

 * corresponding hardware register bit value and writes it to the SMI interface.

 *

 * Return: 0 on success, error code on failure.

 */

static int ksz879x_set_loopback(struct ksz_device *dev, u16 port, u16 val)

{

	u8 stat3 = 0;



	if (val & BMCR_LOOPBACK)

		stat3 |= PORT_PHY_LOOPBACK;



	return ksz_prmw8(dev, port, REG_PORT_STATUS_3, PORT_PHY_LOOPBACK,

			 stat3);

}



/**

 * ksz8_r_phy_ctrl - Translates and reads from the SMI interface to a MIIM PHY

 *		     Control register (Reg. 31).
@@ -731,16 +782,20 @@ static int ksz8_r_phy_bmcr(struct ksz_device *dev, u16 port, u16 *val) 
	if (ret)

		return ret;



	if (restart & PORT_PHY_LOOPBACK)

		*val |= BMCR_LOOPBACK;



	if (ctrl & PORT_FORCE_100_MBIT)

		*val |= BMCR_SPEED100;



	if (ksz_is_ksz88x3(dev)) {

		if (restart & KSZ8873_PORT_PHY_LOOPBACK)

			*val |= BMCR_LOOPBACK;



		if ((ctrl & PORT_AUTO_NEG_ENABLE))

			*val |= BMCR_ANENABLE;

	} else {

		ret = ksz879x_get_loopback(dev, port, val);

		if (ret)

			return ret;



		if (!(ctrl & PORT_AUTO_NEG_DISABLE))

			*val |= BMCR_ANENABLE;

	}
@@ -1001,8 +1056,7 @@ static int ksz8_w_phy_bmcr(struct ksz_device *dev, u16 port, u16 val) 


	restart = 0;

	restart_mask = PORT_LED_OFF | PORT_TX_DISABLE | PORT_AUTO_NEG_RESTART |

		PORT_POWER_DOWN | PORT_AUTO_MDIX_DISABLE | PORT_FORCE_MDIX |

		PORT_PHY_LOOPBACK;

		PORT_POWER_DOWN | PORT_AUTO_MDIX_DISABLE | PORT_FORCE_MDIX;



	if (val & KSZ886X_BMCR_DISABLE_LED)

		restart |= PORT_LED_OFF;
@@ -1022,8 +1076,16 @@ static int ksz8_w_phy_bmcr(struct ksz_device *dev, u16 port, u16 val) 
	if (val & KSZ886X_BMCR_FORCE_MDI)

		restart |= PORT_FORCE_MDIX;



	if (ksz_is_ksz88x3(dev)) {

		restart_mask |= KSZ8873_PORT_PHY_LOOPBACK;



		if (val & BMCR_LOOPBACK)

		restart |= PORT_PHY_LOOPBACK;

			restart |= KSZ8873_PORT_PHY_LOOPBACK;

	} else {

		ret = ksz879x_set_loopback(dev, port, val);

		if (ret)

			return ret;

	}



	return ksz_prmw8(dev, port, regs[P_NEG_RESTART_CTRL], restart_mask,

			 restart);

drivers/net/dsa/microchip/ksz8795_reg.h

+1 −0
Original line number Diff line number Diff line
@@ -265,6 +265,7 @@ 
#define PORT_AUTO_MDIX_DISABLE		BIT(2)

#define PORT_FORCE_MDIX			BIT(1)

#define PORT_MAC_LOOPBACK		BIT(0)

#define KSZ8873_PORT_PHY_LOOPBACK	BIT(0)



#define REG_PORT_1_STATUS_2		0x1E

#define REG_PORT_2_STATUS_2		0x2E