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Application Note
How to Integrate Linux Driver Into Your System

Alvaro Reyes
ABSTRACT
Linux drivers are essential software components that allow the operating system to communicate with hardware
devices such as graphics cards, printers, and Ethernet physical layer devices (PHY). Without the drivers, Linux
is unable to use the hardware effectively, resulting in devices not being recognized or functioning properly. This
document aims to provide comprehensive guidance for developers seeking to integrate PHY functionality into
Linux-based systems. By detailing the intricacies of PHY driver implementation within the Linux kernel, this
application note equips developers with the knowledge and tools necessary to make sure seamless integration,
designed for performance, and compatibility across a wide range of hardware platforms.

Table of Contents
1 Texas Instruments Ethernet PHY Drivers............................................................................................................................. 2
2 Ethernet PHY Driver Overview.............................................................................................................................................. 2
2.1 Exploring Linux Driver Types............................................................................................................................................. 3
3 Driver Integration....................................................................................................................................................................4
3.1 Linux Device Tree.............................................................................................................................................................. 4
3.2 Integrating Driver................................................................................................................................................................7
4 Common Terminal Commands.............................................................................................................................................. 8
4.1 Initialization Commands..................................................................................................................................................... 8
4.2 Functional Commands..................................................................................................................................................... 10
4.3 Diagnostic Commands..................................................................................................................................................... 12
5 Summary............................................................................................................................................................................... 16
6 References............................................................................................................................................................................ 16
Trademarks
All trademarks are the property of their respective owners.

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Texas Instruments Ethernet PHY Drivers www.ti.com

1 Texas Instruments Ethernet PHY Drivers

All Ethernet drivers, RTOS and Linux, can be found at TI's Ethernet software github.
Table 1-1. TI Ethernet PHY Drivers
Driver Supported Devices U-boot Driver Linux Driver
dp83822.c DP83822 N/A Yes, all can be found here: TI's
Ethernet software github
DP83825 N/A
DP83826 N/A
dp83848.c DP83848 N/A
DP83620 N/A
dp83867.c DP83867 Yes
dp83869.c DP83869 Yes
dp83tc811.c DP83TC812 N/A
dp83tc812.c DP83TC812 N/A
DP83TC813 N/A
DP83TC814 N/A
dp83tg720.c DP83TG720 N/A
DP83TG721 N/A

2 Ethernet PHY Driver Overview

Ethernet PHY Linux drivers play a crucial role in enabling communication between the network interface
controller (NIC) and the physical Ethernet medium. The drivers interact with the Linux kernel's networking
subsystem, providing a standardized interface for high-level networking protocols and applications. Implementing
Ethernet PHY drivers involves handling tasks such as auto-negotiation, link detection, speed and duplex
configuration, and error handling. Additionally, these drivers often support various Ethernet standards, including
10/100/1000Mbps Ethernet.
Figure 2-1 serves as an example that illustrates the role of an Ethernet PHY driver. Starting from the top, the
user inputs a command through the Terminal (an ethtool command, for example). Ethtool, a Linux network utility,
takes the input provided by the user in the terminal and checks if the parameters given are valid. This is an
important step that provides a high-level interface for the user to interact with the kernel, without having direct
Kernel control. If the parameters are correct, ethtool passes the command to the MAC and PHY drivers. The
drivers have function definitions to execute the commands that were originally provided by the user and apply
them to the hardware.

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Console Terminal (User Input)

Network Utilities
Applications iperf ping ethtool

User Space

Kernel Space

Linux Network Support

Ctrl/Status
MAC Driver PHY Driver

Software

Hardware

Data Flow Ethernet Cable

MAC PHY

Figure 2-1. Linux Driver Block Diagram

2.1 Exploring Linux Driver Types

Within the Linux operating system, there are two main driver types that are discussed in this application note:
Kernel and U-boot.
2.1.1 U-Boot Driver
A U-boot driver is a software component designed specifically for the U-Boot bootloader, which is commonly
used in embedded systems and bootstrapping processes. These drivers enable U-Boot to interact with and
control various hardware peripherals during the boot-up sequence. This provides proper system initialization and
hardware setup before handing over control to the operating system kernel.
2.1.2 Kernel Driver
A kernel driver, also known simply as driver, is a software component that enables the operating system
kernel to communicate with and control hardware devices. These drivers are integrated into the kernel and
are responsible for managing the interactions between software applications and hardware peripherals such as
network adapters, storage drives, input or output devices, and more. Kernel drivers handle tasks such as device
initialization, data transfer, interrupt handling, power management, and error handling.

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3 Driver Integration
Integrating a driver into a Linux system involves several key steps to provide seamless compatibility and
functionality. Initially, developers must compile the driver code to generate a loadable kernel module or
incorporate the code directly into the kernel (the latter is preferred for faster PHY recognition during MDIO
probe).
The following sections describe the process in greater detail with the following setup. The J721EXCPXEVM
common processor board is used with the J721EXSOMG01EVM TDA4VM and DRA829V socketed system on
module. The Linux-RT SDK is used to evaluate Linux Kernel version 5.10 on the board. The common processor
board natively has one Ethernet port, using the DP83867E Ethernet PHY. A plug in daughter card with four
additional Ethernet ports is plugged into the common processor board's EVM expansion connector, where the
drivers for the Ethernet PHYs are not included in the processor's SDK.
3.1 Linux Device Tree
A Linux device tree is a data structure used to describe the hardware components and configuration in
embedded systems. The device tree provides a standardized way for the operating system to understand the
hardware layout, including details about the processor, memory, buses. and peripherals. Device tree data is
typically stored in a binary format (.dtb file) and is passed to the Linux kernel during boot-up. The kernel then
uses this information to dynamically bind device tree nodes and initialize hardware components, allowing for
efficient and flexible hardware support across different embedded platforms without the need for hard-coding
hardware details into the kernel.
The Device Tree Codeblock is an example of how four Ethernet PHYs on the daughter card are configured in the
device tree file. CPSW refers to the MAC interface of the processor and the main node definitions to consider
are:
• &cpsw0 {} which initializes four RGMII interfaces
• cpsw0_portn {} which initializes further details for each port
– phy-mode: sets the MAC interface of that port
– phy-handle: defines how to set up the PHY
• <&cpsw9g_phyx> is used to set the PHY Address
– Note that x does not set the PHY Address and is only a naming convention. The address is
assigned lower in the Device Tree Codeblock, inside the cpsw9g_mdio{} definition.
• reg = <x>;
•
RGMII delays can be set here too, an example can be seen in the J721E common processor board dts
file, line 744, and in the RGMII Codeblock.
– Typically our RGMII delay recommendation is to configure the PHY to delay both TX and RX CLK
by 2.0ns (referred to as shift mode), while the processor is set to 0 delay (referred to as align
mode). See Table 3-1 for more information.
• However, many TI processors have an internal 2.0ns delay on the TX lines that cannot be
disabled. In the RGMII Codeblock, only RX delay is configured on the PHY for this reason.
– phys
• Setting which eth# each port is assigned
– <&cpsw0_phy_gmii_sel n>

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Table 3-1. RGMII Shift Configurations

MAC Configuration Required PHY Configuration
Align on RX Shift on RX
Shift on RX Align on RX
Align on TX Shift on TX
Shift on TX Align on TX

RGMII Codeblock:

&davinci_mdio {
phy0: ethernet-phy@0 { //PHY0 is defined and passed to phy-handle
reg = <0>;
ti,rx-internal-delay = <DP83867_RGMIIDCTL_2_00_NS>;
ti,fifo-depth = <DP83867_PHYCR_FIFO_DEPTH_4_B_NIB>;
};
};

&cpsw_port1 {
phy-mode = "rgmii-rxid";
phy-handle = <&phy0>;
};

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Device Tree Codeblock:

&cpsw0 {
status = "okay";
pinctrl-names = "default";
pinctrl-0 = <&mdio_pins_default
&rgmii1_pins_default
&rgmii2_pins_default
&rgmii3_pins_default
&rgmii4_pins_default
>;
};

&cpsw0_port1 {
phy-handle = <&cpsw9g_phy0>;
phy-mode = "rgmii-rxid";
mac-address = [00 00 00 00 00 00];
phys = <&cpsw0_phy_gmii_sel 1>;
};

&cpsw0_port2 {
phy-handle = <&cpsw9g_phy4>;
phy-mode = "rgmii-rxid";
mac-address = [00 00 00 00 00 00];
phys = <&cpsw0_phy_gmii_sel 2>;
};

&cpsw0_port3 {
phy-handle = <&cpsw9g_phy5>;
phy-mode = "rgmii-rxid";
mac-address = [00 00 00 00 00 00];
phys = <&cpsw0_phy_gmii_sel 3>;
};

&cpsw0_port4 {
phy-handle = <&cpsw9g_phy8>;
phy-mode = "rgmii-rxid";
mac-address = [00 00 00 00 00 00];
phys = <&cpsw0_phy_gmii_sel 4>;
};
&cpsw9g_mdio {
bus_freq = <1000000>;
#address-cells = <1>;
#size-cells = <0>;

cpsw9g_phy0: ethernet-phy@0 {
reg = <0>;
};
cpsw9g_phy4: ethernet-phy@4 {
reg = <4>;
};
cpsw9g_phy5: ethernet-phy@5 {
reg = <5>;
};
cpsw9g_phy8: ethernet-phy@8 {
reg = <8>;
};
};

When the board is running, the terminal command dmesg grep | mdio can be used to confirm the PHY address
(phy[x]) and eth port (ethn).

davinci_mdio c000f00.mdio: phy[0]: device c000f00.mdio:00, driver TI DP83TG720CS1.1

davinci_mdio c000f00.mdio: phy[4]: device c000f00.mdio:04, driver TI DP83TG721CS1.0
davinci_mdio c000f00.mdio: phy[5]: device c000f00.mdio:05, driver TI DP83TC812CS2.0
davinci_mdio c000f00.mdio: phy[8]: device c000f00.mdio:08, driver TI DP83TC814CS2.0
am65-cpsw-nuss c000000.ethernet eth4: PHY [c000f00.mdio:08] driver [TI DP83TC814CS2.0] (irq=POLL)
am65-cpsw-nuss c000000.ethernet eth3: PHY [c000f00.mdio:05] driver [TI DP83TC812CS2.0] (irq=POLL)
am65-cpsw-nuss c000000.ethernet eth2: PHY [c000f00.mdio:04] driver [TI DP83TG721CS1.0] (irq=POLL)
am65-cpsw-nuss c000000.ethernet eth1: PHY [c000f00.mdio:00] driver [TI DP83TG720CS1.1] (irq=POLL)

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3.2 Integrating Driver

This section describes how to add a driver (newDriver.c, where newDriver is an Ethernet PHY) to an SDK on a
linux system that is either missing the driver or using an outdated version.
In the SDK, find the Linux kernel directory (LKD). An example file path looks like:
SDK_Install_Directory/board-support/TI-linux-kernel/

TI-Linux-kernel is the LKD in this example. From here, you can navigate to:
LKD/drivers/net/phy/

Copy newDriver.c into this directory. Within this same directory are Makefile and Kconfig , both files need to be
edited for newDriver.c to be built.
Edit Makefile
Add the following line to the Makefile. Note the assignment is newDriver.o and not newDriver.c
obj-$(CONFIG_newDriver_PHY) += newDriver.o

Edit Kconfig
Add the following lines to the Kconfig,
config newDriver PHY
tristate "<Insert Company name> newDriver PHY"
--help--
Supports the newDriver PHY.

After both the Makefile and Kconfig files have been edited, return to the LKD. From here, go to:
LKD/arch/arm64/configs

Note
If your processor is 32 bit instead of 64 bit, go into the 'arm' folder instead of 'arm64'.

Here you can find a defconfig file, add the following line:
CONFIG_newDriver_PHY = y

The naming convention, CONFIG_newDriver_PHY, needs to match what was set in the Makefile.
From here, you can return to the SDK install directory and run the make command on the terminal.

Note
Not all kernel's can be built by running make, consult your SDK's documentation for correct procedure
to build kernel, u-boot, and dtb files.

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4 Common Terminal Commands

The following are several commands accompanied with descriptions, use cases, and terminal outputs.
4.1 Initialization Commands
After system bootup, the following commands state whether the driver was loaded correctly or not.
4.1.1 dmesg | grep -i mdio
Dmesg is a Linux command that displays messages written to the kernel. The | symbol is known as the
pipe command, which connects the output of one command directly into the input of another. Grep is a Linux
command used to find strings and the -i parameter ignores the case of the string. Overall, dmesg | grep -i mdio
finds all messages written to the kernel and filters for those containing mdio. The MDIO interface is how the
processor can access the PHY's registers.
The purpose of this command is to confirm if the driver is loaded correctly or provide several debug clues on
what is causing the PHY to misbehave from a software standpoint.
Examples of bad output:

davinci_mdio c000f00.mdio: phy[10]: device c000f00.mdio:0a, MDIO device at address 10 is missing.

This message indicates that the PHY is not found on the MDIO bus, which can be caused by several issues. The
most common being a missing or incorrect device tree (see Section 3.1 for more information), but can also be
due to a non-functional PHY or a bad MDIO connection.
Once the PHY can be detected on the MDIO bus, another common error message is:

am65-cpsw-nuss c000000.ethernet eth1: PHY [c000f00.mdio:0a] driver [Generic PHY] (irq=POLL)

davinci_mdio c000f00.mdio: phy[10]: device c000f00.mdio:0a, driver unknown

Both the driver unknown and Generic PHY messages indicate that the driver file is not loaded correctly, built,
or completely missing; and Linux loaded a generic driver that won't function well with the PHY. In this case,
verify that the driver was successfully compiled and added to Linux. See Section 3.2 for more information on this
process.
Finally, an example of a good output looks like this:

root@j7-evm:~# dmesg | grep mdio

davinci_mdio 46000f00.mdio: phy[0]: device 46000f00.mdio:00, driver TI DP83867
am65-cpsw-nuss 46000000.ethernet eth0: PHY [46000f00.mdio:00] driver [TI DP83867] (irq=POLL)

Here we can see the phy[0] is identified as the DP83867 and assigned as port eth0

Note
PHY[n], where n represents the PHY Address can be different than the ethx where x represents which
port that PHY is assigned to. For example, PHY address can be 8 while being assigned to port eth0.

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4.1.2 ifconfig
ifconfig(case sensitive) is a Linux terminal command that displays network interfaces and can also be used to
determine if the driver has been loaded correctly. ifconfig -ethx down deactivates the interface and ifconfig
-ethx up activates it; which loads the driver again, similarly to when the board is powered on initially.
root@j7-evm:~# ifconfig
docker0: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500 metric 1
inet 172.17.0.1 netmask 255.255.0.0 broadcast 172.17.255.255
ether 02:42:f9:5b:d7:a4 txqueuelen 0 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

eth0: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500 metric 1

ether 34:08:e1:59:5c:d2 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

eth1: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500 metric 1

ether d2:eb:75:2d:68:21 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536 metric 1

inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 1000 (Local Loopback)
RX packets 82 bytes 6220 (6.0 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 82 bytes 6220 (6.0 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

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4.2 Functional Commands

The commands listed in this section provide a service or function.
4.2.1 Phytool
Phytool is a Linux command for MDIO register access, this provides an easy way to read and write registers of a
PHY. This tool is already integrated into TI SDK’s but can be downloaded by entering the following sudo apt-get
install -y net-tools.
Phytool command:
• phytool read ethx/PHYADDRESS/desiredRegister
• phytool write ethx/PHYADDRESS/desiredRegister writeValue

root@j7-evm:~# phytool read eth1/10/0x0 //Read Register 0x0

0x1140 //Result
root@j7-evm:~# phytool write eth1/10/0x0 0x0140 //Write Reg 0x0 = 0x0140
root@j7-evm:~# phytool read eth1/10/0x0 //Read again to confirm write command
0x0140

4.2.2 Ethtool
Ethtool is used to access or change network driver settings.
• Ethtool -ethx
– Ethx represents which network device you are referring to. If a board has two Ethernet ports, there can be
eth0 and eth1
– Command tells current status and configuration of that Ethernet device
• This is an easy way to confirm the PHYADDRESS of a port

ethtool eth0
Settings for eth0:
Supported ports: [ TP MII ]
Supported link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Full
Supported pause frame use: Symmetric
Supports auto-negotiation: Yes
Supported FEC modes: Not reported
Advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Full
Advertised pause frame use: Symmetric
Advertised auto-negotiation: Yes
Advertised FEC modes: Not reported
Link partner advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Full
Link partner advertised pause frame use: Symmetric Receive-only
Link partner advertised auto-negotiation: Yes
Link partner advertised FEC modes: Not reported
Speed: 1000Mb/s
Duplex: Full
Auto-negotiation: on
master-slave cfg: preferred slave
master-slave status: slave
Port: Twisted Pair
PHYAD: 0
Transceiver: external
MDI-X: Unknown
Supports Wake-on: ubgs
Wake-on: d
SecureOn password: 00:00:00:00:00:00
Current message level: 0x000020f7 (8439)
drv probe link ifdown ifup rx_err tx_err hw
Link detected: yes

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4.2.3 Forced Master/Slave

This function forces the network interface into Master/Slave, without the user needing to know which registers
to write to. This is particularly important for Single Pair Ethernet devices (SPE). In SPE communication, there
needs to be a Master and Slave, both cannot be Master or Slave.
In the following codeblock, the ethtool command is used to check the current state of the PHY, then the state is
changed to the other and checked again.
Command:
• ethtool -s ethx master-slave forced-master
• ethtool -s ethx master-slave forced-slave

Note
This command has no output. ethtool eth3 | grep master-slave is run to check the current status

root@j7-evm:~# ethtool eth3 | grep master-slave

master-slave cfg: forced master
master-slave status: master
root@j7-evm:~# ethtool -s eth3 master-slave forced-slave
root@j7-evm:~# ethtool eth3 | grep master-slave
master-slave cfg: forced slave
master-slave status: slave
root@j7-evm:~#

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4.3 Diagnostic Commands

The commands listed in this section are for debugging Ethernet specific application issues.
4.3.1 SQI
Signal Quality Indicator (SQI), a feature that is not implemented in all PHYs, is used to check the quality of the
signal (0 being no link and 7 the best possible). Useful for debugging the origin of errors, for example: link is
stable but the system is seeing packet loss. A low SQI value indicates the issue is likely within the MDI interface
(connector side). If SQI is implemented in the device's driver, SQI can be found in the ethtool command. If you
only want to display the SQI, you can use ethtool ethx | grep SQI.
ethtool eth3
Settings for eth3:
Supported ports: [ TP MII ]
Supported link modes: 100baseT/Full
Supported pause frame use: Symmetric
Supports auto-negotiation: No
Supported FEC modes: Not reported
Advertised link modes: Not reported
Advertised pause frame use: Symmetric
Advertised auto-negotiation: No
Advertised FEC modes: Not reported
Speed: 100Mb/s
Duplex: Full
Auto-negotiation: off
master-slave cfg: forced master
master-slave status: master
Port: Twisted Pair
PHYAD: 5
Transceiver: external
MDI-X: Unknown
Supports Wake-on: d
Wake-on: d
Current message level: 0x000020f7 (8439)
drv probe link ifdown ifup rx_err tx_err hw
Link detected: yes
SQI: 4/7
ethtool eth3 | grep SQI
SQI: 4/7

4.3.2 TDR
Time Domain Reflectometer (TDR) is a function that identifies a fault in the cable. Not all Ethernet PHYs have
the TDR feature, be sure to check the PHY's data sheet to confirm. For TI's automotive single pair Ethernet
(SPE) PHYs to correctly run TDR, the Master/Slave state of the PHY must be known.
When PHY is Master:
• If cable is connected (good link)
– PHY drops link, performs TDR, and regains link
• If cable is disconnected or damaged
– PHY performs TDR and outputs:
• Fault Type
– Open or Short
• Distance of fault in meters
When PHY is Slave:
• If cable is connected (good link)
– Link partner (Master) needs to be forced silent (not transmitting any packets), otherwise TDR will fail
• Cable can be disconnected from Master to run TDR as Slave
In the codeblock below, eth3 is initially linked up with a known good cable and configured as Master. TDR is run
and completes as expected, with no fault detected. After TDR is completed, the cable is unplugged from the link
partner, resulting in eth3: Link is Down. TDR is then run again.

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TDR command: ethtool --cable-test ethx

root@j7-evm:~# ethtool --cable-test eth3
am65-cpsw-nuss c000000.ethernet eth3: Link is Down
PHY is set as Master.
Cable test started for device eth3.
Cable test completed for device eth3.
Pair A code OK
TDR HAS COMPLETED AND PASSED
root@j7-evm:~# No Fault Detected.
am65-cpsw-nuss c000000.ethernet eth3: Link is Up - 100Mbps/Full - flow control off

am65-cpsw-nuss c000000.ethernet eth3: Link is Down

root@j7-evm:~# ethtool --cable-test eth3

PHY is set as Master.
Cable test started for device eth3.
Cable test completed for device eth3.
Pair A code Open Circuit
TDR HAS COMPLETED AND PASSED
Open Cable Detected
Length of Fault: 3 Meters

In the codeblock below, eth4 is initially linked up with a known good cable and configured as Slave. TDR is run
and fails as expected. Next the cable is unplugged from the link partner, resulting in eth4: Link is Down. TDR is
then run again.
root@j7-evm:~# ethtool --cable-test eth4
am65-cpsw-nuss c000000.ethernet eth4: Link is Down
PHY is set as Slave.
Cable test started for device eth4.
Cable test completed for device eth4.
TDR HAS FAILED
root@j7-evm:~# am65-cpsw-nuss c000000.ethernet eth4: Link is Up - 100Mbps/Full - flow control off

am65-cpsw-nuss c000000.ethernet eth4: Link is Down

root@j7-evm:~# ethtool --cable-test eth4

PHY is set as Slave.
Cable test started for device eth4.
Cable test completed for device eth4.
Open Circuit
TDR HAS COMPLETED AND PASSED
Open Cable Detected
Length of Fault: 3 Meters

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4.3.3 Throughput Testing - Ping and iPerf

Throughput testing refers to sending data from one board to another. An initial ping test can be performed first to
confirm communication with the destination is possible. The following example demonstrates the most basic type
of ping, where the host is directly connected to the destination. This example does not include any kind of switch,
hub, or router.
Ping Example:A testboard running Linux is connected to a Linux PC through an Ethernet cable.
1. On the Linux PC, open a terminal and run the ifconfig command to find the IPV4 Address
a. (169.254.132.246 in this example, labeled inet)
2. On the testboard, run ifconfig 169.254.132.250 to assign a static IP address
a. Note that the address only has the final three decimals changed to be unique
i. Known as the host ID
b. The rest of the address (169.254.132) must be the same
i. Known as the network ID
3. From the testboard, run ping 169.254.132.246(the IP address of the Linux PC)
a. Ping begins and can be stopped by pressing 'ctrl' and 'c' at the same time.
The codeblock below is captured from the testboard pinging to the Linux PC, but ping can be performed both
ways, for example, Linux PC can also ping the testboard.

Linux Test Board Ethernet Cable Linux PC

(169.254.132.250) (169.254.132.246)

Figure 4-1. Ping Block Diagram Example

root@j7-evm:~# ifconfig eth0 169.254.132.250

root@j7-evm:~# ifconfig eth0
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 metric 1
inet 169.254.132.250 netmask 255.255.0.0 broadcast 169.254.255.255
inet6 fe80::3608:e1ff:fe59:5cd2 prefixlen 64 scopeid 0x20<link>
ether 34:08:e1:59:5c:d2 txqueuelen 1000 (Ethernet)
RX packets 133 bytes 16347 (15.9 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 481 bytes 117318 (114.5 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

root@j7-evm:~# ping 169.254.132.246

PING 169.254.132.246 (169.254.132.246): 56 data bytes
64 bytes from 169.254.132.246: seq=0 ttl=64 time=0.579 ms
64 bytes from 169.254.132.246: seq=1 ttl=64 time=0.546 ms
64 bytes from 169.254.132.246: seq=2 ttl=64 time=0.587 ms
64 bytes from 169.254.132.246: seq=3 ttl=64 time=0.557 ms
64 bytes from 169.254.132.246: seq=4 ttl=64 time=0.518 ms
64 bytes from 169.254.132.246: seq=5 ttl=64 time=0.574 ms
64 bytes from 169.254.132.246: seq=6 ttl=64 time=0.548 ms
64 bytes from 169.254.132.246: seq=7 ttl=64 time=0.561 ms
^C
--- 169.254.132.246 ping statistics ---
8 packets transmitted, 8 packets received, 0% packet loss
round-trip min/avg/max = 0.518/0.558/0.587 ms
root@j7-evm:~#

With ping successfully working, we can attempt to perform a throughput test using iPerf, an open-source tool
used to measure network performance/bandwidth. iPerf needs to be installed on both machines (testboard and
Linux PC) to function.

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www.ti.com Common Terminal Commands

iPerf Example:
1. On the test board, run the command iperf -s to configure the test board as the server.
2. On the Linux PC, run the command iperf -c 169.254.132.250 (the IP address of the server), to configure the
Linux PC as a client and connects to the server.
The codeblock below is captured from the testboard. Here we can see 1.09 GB of data successfully transferred
and the Bandwidth is very close to the advertised speed of the network port (1000Mbps).
root@j7-evm:~# iperf -s
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 128 KByte (default)
------------------------------------------------------------
[ 4] local 169.254.132.250 port 5001 connected with 169.254.132.246 port 37356
[ ID] Interval Transfer Bandwidth
[ 4] 0.0-10.0 sec 1.09 GBytes 933 Mbits/sec //This step happens after the Linux PC connects
as a client

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Summary www.ti.com

5 Summary
This application note provides a comprehensive overview of basic Linux PHY driver terminology, guiding users
through the integration of a new Ethernet driver into a system and offering insights into common terminal
commands for debugging purposes. From foundational concepts to practical implementation, this resource
equips developers with the knowledge and tools necessary to navigate the complexities of Linux driver
development efficiently.
6 References
• Texas Instruments, ti-ethernet-software Github.
• Ethtool, Linux Manual Page.
• iPerf, Speed Test Tool.

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