5.4-stable review patch. If anyone has any objections, please let me know.
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From: Claudiu Beznea claudiu.beznea.uj@bp.renesas.com
[ Upstream commit e398822c4751017fe401f57409488f5948d12fb5 ]
The RZ/G3S SMARC Module has 2 KSZ9131 PHYs. In this setup, the KSZ9131 PHY is used with the ravb Ethernet driver. It has been discovered that when bringing the Ethernet interface down/up continuously, e.g., with the following sh script:
$ while :; do ifconfig eth0 down; ifconfig eth0 up; done
the link speed and duplex are wrong after interrupting the bring down/up operation even though the Ethernet interface is up. To recover from this state the following configuration sequence is necessary (executed manually):
$ ifconfig eth0 down $ ifconfig eth0 up
The behavior has been identified also on the Microchip SAMA7G5-EK board which runs the macb driver and uses the same PHY.
The order of PHY-related operations in ravb_open() is as follows: ravb_open() -> ravb_phy_start() -> ravb_phy_init() -> of_phy_connect() -> phy_connect_direct() -> phy_attach_direct() -> phy_init_hw() -> phydev->drv->soft_reset() phydev->drv->config_init() phydev->drv->config_intr() phy_resume() kszphy_resume()
The order of PHY-related operations in ravb_close is as follows: ravb_close() -> phy_stop() -> phy_suspend() -> kszphy_suspend() -> genphy_suspend() // set BMCR_PDOWN bit in MII_BMCR
In genphy_suspend() setting the BMCR_PDWN bit in MII_BMCR switches the PHY to Software Power-Down (SPD) mode (according to the KSZ9131 datasheet). Thus, when opening the interface after it has been previously closed (via ravb_close()), the phydev->drv->config_init() and phydev->drv->config_intr() reach the KSZ9131 PHY driver via the ksz9131_config_init() and kszphy_config_intr() functions.
KSZ9131 specifies that the MII management interface remains operational during SPD (Software Power-Down), but (according to manual): - Only access to the standard registers (0 through 31) is supported. - Access to MMD address spaces other than MMD address space 1 is possible if the spd_clock_gate_override bit is set. - Access to MMD address space 1 is not possible.
The spd_clock_gate_override bit is not used in the KSZ9131 driver.
ksz9131_config_init() configures RGMII delay, pad skews and LEDs by accessesing MMD registers other than those in address space 1.
The datasheet for the KSZ9131 does not specify what happens if registers from an unsupported address space are accessed while the PHY is in SPD.
To fix the issue the .soft_reset method has been instantiated for KSZ9131, too. This resets the PHY to the default state before doing any configurations to it, thus switching it out of SPD.
Fixes: bff5b4b37372 ("net: phy: micrel: add Microchip KSZ9131 initial driver") Signed-off-by: Claudiu Beznea claudiu.beznea.uj@bp.renesas.com Reviewed-by: Maxime Chevallier maxime.chevallier@bootlin.com Reviewed-by: Andrew Lunn andrew@lunn.ch Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/phy/micrel.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/drivers/net/phy/micrel.c b/drivers/net/phy/micrel.c index 721153dcfd15..caaa51a70cbd 100644 --- a/drivers/net/phy/micrel.c +++ b/drivers/net/phy/micrel.c @@ -1156,6 +1156,7 @@ static struct phy_driver ksphy_driver[] = { /* PHY_GBIT_FEATURES */ .driver_data = &ksz9021_type, .probe = kszphy_probe, + .soft_reset = genphy_soft_reset, .config_init = ksz9131_config_init, .read_status = genphy_read_status, .ack_interrupt = kszphy_ack_interrupt,