Hi,
we are trying to evaluate if we can implement an ethernet port on the i.MX95 that is able to support the following ethernet speeds:
- 10GBASE-T
- 5GBASE-T
- 2.5GBASE-T
- 1000BASE-T
- 100BASE-TX
- 10BASE-Te
In general this requires us to place a 10Gbit capable ethernet PHY on our design and connect it to the i.MX95 ethernet controller via one of two interfaces: USXGMII or XFI
From our understanding the USXGMII interface is a multi-rate interface in theory, meaning it can facilitate all speeds from 10Gbit to 10bit over one link.
In contrast the XFI interface is a single-rate interface that can only facilitate 10Gbit.
According to the i.MX95 reference manual (e.g. section 104.2, table 621) the i.MX95 supports both XFI and "10G-USXGMII". So initially it looks like our desired interface USXGMII seems to be supported.
There are several points that confuse us however:
1. The declaration "10G-USXGMII" could be interpreted to mean that the interface is a USXGMII link in theory but it only really works in the 10Gbit mode.
2. The NXP eval board IMX95LPD5EVK-19 implements a 10GBase-T port using a Marvell AQR113C PHY.
a) In the block diagram in figure 1, section 1.1 the PHY looks to be connected to the USXGMII interface:
b) In the associated section 2.11.3 "10 Gbit Ethernet Interface" the AQR113C ethernet transceiver is said to support all data rates from 10Gbit to 10bit, hinting at true USXGMII:
c) This section also mentions that the interface used to connect the ethernet PHY is XFI:
So in conclusion we are confused wether or not the i.MX95 supports the full multi-rate USXGMII or only a 10Gbit-only version.
We tried to look at the NXP eval board as a reference but we are not sure either if the 10GbE port on that board is connected via USXGMII (allowing multi-rate from 10Gbit to 10bit) or via XFI (10Gbit only).
Could you please clarify for us: Is it possible to implement a true multi-rate 10GbE port on the i.MX95 that supports speeds from 10Gbit to 10bit?
This clears up any confusion on our side!
1. Meaning of "10G-USXGMII"
"10G-USXGMII" refers to the standard multi-rate USXGMII protocol, not a 10G-only mode. The "10G" denotes the fixed SerDes lane speed, while USXGMII supports in-band rate adaptation for 10M, 100M, 1G, 2.5G, 5G, and 10G Ethernet.
On i.MX95, this mode is represented by the PCS_PROT_10G_SXGMII setting.
2. Interface Used on the i.MX95 EVK
The i.MX95 EVK uses XFI (10GBASE-R) rather than USXGMII. In imx95-19x19-evk.dts, enetc_port2 is configured as:
phy-mode = "10gbase-r";
Therefore, the onboard AQR113C operates in XFI mode.
3. Is True Multi-Rate USXGMII Supported?
Yes. The i.MX95 NETC hardware supports USXGMII, and the Linux ENETC4 driver handles speed changes through enetc4_set_port_speed(). The Marvell AQR113C also supports USXGMII host-interface mode.
4. What Is Needed on a Custom Board?
To enable full multi-rate operation:
Configure the device tree:
phy-mode = "usxgmii";
managed = "in-band-status";
Configure the AQR113C firmware for USXGMII host mode instead of XFI.
The EVK uses XFI for its 10GbE port, but a custom i.MX95 design can use USXGMII with the AQR113C (or a similar PHY) to support 10M/100M/1G/2.5G/5G/10G over a single MAC-to-PHY link.
Thanks
I am not the original poster but I am also trying to get usxgmii working.
Has NXP ever validated if usxgmii works on the BSP kernel? I am trying to use it with a mv-cux3610 phy but I get these errors:
[ 43.063202] nxp_enetc4 0002:00:10.0 (unnamed net_device) (uninitialized): MAC returned PCS which does not support usxgmii
[ 43.074224] nxp_enetc4 0002:00:10.0 (unnamed net_device) (uninitialized): failed to validate link configuration for inband
[ 43.085308] nxp_enetc4 0002:00:10.0: Failed to create phylink
[ 43.091726] nxp_enetc4 0002:00:10.0: probe with driver nxp_enetc4 failed with error -22it seems to be caused by the netc PCS not advertising usxgmii support, only 10gbase-r, 2500-basex and sgmii:
(this is on the lf-6.18.y linux-imx branch)
Last question from my side: Is it possible to configure the enetc_port2 and the AQR113C on the i.MX95 EVK to USXGMII mode? Would this allow us to test the multi-rate functionality of the USXGMII interface on the EVK?
the driver has been included in NXP Linux BSP, link:
Simply "switching the DTS to usxgmii" on the EVK is only a software-level attempt.
You would also have to re-provision the AQR113C with USXGMII firmware, and because of the EVK's XFI-oriented board design, this is not a reliable path for multi-rate validation.
If the goal is to validate true multi-rate USXGMII (10M/100M/1G/2.5G/5G/10G), we recommend building a custom board designed for USXGMII (SerDes routing + AQR113C in USXGMII host-mode firmware + phy-mode = "usxgmii").
You can use EVK board, after obtaining the USXGMII provisioning firmware for the AQR113C, but please be aware of its limitations.
Thanks