On Thu, Jan 14, 2021 at 08:38:12AM +0000, ashid...@fujitsu.com wrote:
> Hi Andrew
>
> > For T1, it seems like Master is pretty important. Do you have
> > information to be able to return the current Master/slave
> > configuration, or allow it to be configured? See the nxp-tja11xx.c for
> > an example.
>
> Do you know how to switch between master/slave?
There was a patch to ethtool merged for this:
commit 558f7cc33daf82f945af432c79db40edcbe0dad0
Author: Oleksij Rempel <o.rem...@pengutronix.de>
Date: Wed Jun 10 10:37:43 2020 +0200
netlink: add master/slave configuration support
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
-------------------------------------------------------------------------------
Andrew
