On Tue, May 05, 2020 at 08:35:05AM +0200, Oleksij Rempel wrote: > This UAPI is needed for BroadR-Reach 100BASE-T1 devices. Due to lack of > auto-negotiation support, we needed to be able to configure the > MASTER-SLAVE role of the port manually or from an application in user > space. > > The same UAPI can be used for 1000BASE-T or MultiGBASE-T devices to > force MASTER or SLAVE role. See IEEE 802.3-2018: > 22.2.4.3.7 MASTER-SLAVE control register (Register 9) > 22.2.4.3.8 MASTER-SLAVE status register (Register 10) > 40.5.2 MASTER-SLAVE configuration resolution > 45.2.1.185.1 MASTER-SLAVE config value (1.2100.14) > 45.2.7.10 MultiGBASE-T AN control 1 register (Register 7.32) > > The MASTER-SLAVE role affects the clock configuration: > > ------------------------------------------------------------------------------- > When the PHY is configured as MASTER, the PMA Transmit function shall > source TX_TCLK from a local clock source. When configured as SLAVE, the > PMA Transmit function shall source TX_TCLK from the clock recovered from > data stream provided by MASTER. > > iMX6Q KSZ9031 XXX > ------\ /-----------\ /------------\ > | | | | | > MAC |<----RGMII----->| PHY Slave |<------>| PHY Master | > |<--- 125 MHz ---+-<------/ | | \ | > ------/ \-----------/ \------------/ > ^ > \-TX_TCLK > > ------------------------------------------------------------------------------- > > Since some clock or link related issues are only reproducible in a > specific MASTER-SLAVE-role, MAC and PHY configuration, it is beneficial > to provide generic (not 100BASE-T1 specific) interface to the user space > for configuration flexibility and trouble shooting. > > Signed-off-by: Oleksij Rempel <o.rem...@pengutronix.de>
Reviewed-by: Andrew Lunn <and...@lunn.ch> One issue we might run into in the future is that there is a PHY which has standardized auto-neg, but not master/slave support. The PHY driver cannot override genphy_read_master_slave(phydev) and genphy_setup_master_slave(phydev). So we might need to provide ops for these in the driver structure. But we can delay this until we have such a device. Andrew