On Thu, May 28, 2020 at 01:54:13PM +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> > ---
The patch looks good from technical point of view but I don't like the inconsistency of user interface: 1. Similar to what we discussed earlier on kernel side, you use "Port mode" in "ethtool <dev>" output but the corresponding command line argument for "ethtool -s <dev> ..." is "master-slave". Even if it's documented, it's rather confusing for users. 2. The values for "master-slave" parameter are "master-preferred" and "master-force" (and the same for "slave"). Please use the same form for both, i.e. either "prefer / force" or "preferred / forced". Also, it would be friendlier to users to make the values consistent with "ethtool <dev>" output, e.g. if it says "preferred Master", setting should use something as close as possible, i.e. "preferred-master". Michal
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