How to implement Precision Time Protocol (PTP) on Rpi4?

[lineker10]

I used Precision Time Protocol (PTP)/IEEE-1588 on Raspberry pi3b+ by linuxptp refereed this site. Recently, I upgraded to Raspberry pi 4 and I try to use PTP on Raspberry pi 4. Unfortunately, I cannot use it on raspberry pi 4. Because, I don't see SOF_TIMESTAMPING_TX_SOFTWARE listed.
If anybody knows the solution of it, please answer my problem.

[fortrieb]

Hi @lineker10 ,

there is a Kernel 5.x at Raspberry Pi kernel repository (https://github.com/raspberrypi/linux/tree/rpi-5.3.y). I get PTP working on Raspberry Pi 4 with this kernel and following official documentation on compiling custom kernel (https://www.raspberrypi.org/documentation/linux/kernel/building.md).

Adding mentioned configuration option here after make bcm2711_defconfig and continue compiling.

[lineker10]

Hi @fortrieb
Thank you very much. I will try your advice.

[mikebrady]

Thanks @lineker10. I was able to get software timestamping on the ethernet port with your hint.

pi@raspberryPi4B:~ $ uname -a
Linux raspberryPi4B 5.3.18-v7l+ #1 SMP Wed Jan 8 09:57:24 GMT 2020 armv7l GNU/Linux
pi@raspberryPi4B:~ $ sudo ethtool -T eth0
Time stamping parameters for eth0:
Capabilities:
	software-transmit     (SOF_TIMESTAMPING_TX_SOFTWARE)
	software-receive      (SOF_TIMESTAMPING_RX_SOFTWARE)
	software-system-clock (SOF_TIMESTAMPING_SOFTWARE)
PTP Hardware Clock: none
Hardware Transmit Timestamp Modes: none
Hardware Receive Filter Modes: none
pi@raspberryPi4B:~ $ sudo ethtool -T wlan0
Time stamping parameters for wlan0:
Capabilities:
	software-receive      (SOF_TIMESTAMPING_RX_SOFTWARE)
	software-system-clock (SOF_TIMESTAMPING_SOFTWARE)
PTP Hardware Clock: none
Hardware Transmit Timestamp Modes: none
Hardware Receive Filter Modes: none
pi@raspberryPi4B:~ $ 

[lineker10]

Thank you @mikebrady
I try to run by your help...

[yobertyosua]

I have a question again.
I wanna try to install PTP on my RaspPi 4, but for another Kernel (4.19.y-rt). I did the step https://github.com/twteamware/raspberrypi-ptp for the current Kernel and it works. But if I try to do the same steps but into Kernel 4.19.y-rt, it didnt work. Is PTP not support Kernel 4.19.y-rt?

Thanks before

[gizero]

What exactly "didn't work"? where did you get your kernel 4.19.y-rt from?

[yobertyosua]

Thanks for the response.
So, here are what i got:

where did you get your kernel 4.19.y-rt from?

I got it from https://github.com/raspberrypi/linux/tree/rpi-4.19.y-rt. I typed git clone https://github.com/raspberrypi/linux.git -b rpi-4.19.y-rt on my terminal to get the kernel 4.19.y.rt.
Here is the picture of my actual kernel:

What exactly "didn't work"?

SOF_TIMESTAMPING_TX_SOFTWARE is missing after i rebooted the kernel 4.19.y-rt. I noticed it after i checked it using ethtool -T eth0

Correct me if I'm wrong. I think the answer is https://github.com/twteamware/raspberrypi-ptp/blob/master/kernel-patching.md. And I should patch https://github.com/twteamware/raspberrypi-ptp/blob/master/patches/0001-smsc95xx-use-generic-ethtool_op_get_ts_info-callback.patch using patch
Should I put that patch file in the same folder, where my linux kernel is?

Actually I dont understand how to patch. I just did this:

Can you please help me to understand it?
I already read https://github.com/twteamware/raspberrypi-ptp/issues/3, but it still doesnt help me to understand, how to patch it.

Sorry if I ask too much

[michael-gosselin]

there is a Kernel 5.x at Raspberry Pi kernel repository (https://github.com/raspberrypi/linux/tree/rpi-5.3.y)

@fortrieb thanks for this, super helpful. Does it have to be kernel 5.3.y ? I tried this with a newer kernel (5.15.y) and it didn't work:

$ sudo ethtool -T eth0

gives:

Time stamping parameters for eth0:
Capabilities:
	software-transmit
	software-receive
	software-system-clock
PTP Hardware Clock: none
Hardware Transmit Timestamp Modes: none
Hardware Receive Filter Modes: none

I also notice that ptp4l is not running after I boot:

$ sudo systemctl status ptp4l

gives,

Unit ptp4l.service could not be found.

I am using a raspberry pi 4B.

[fortrieb]

Hi @michael-gosselin, i didn't try a newer kernel then 5.3.y.

[Grisly00]

@michael-gosselin Similarly I am using a new Kernel (5.15.0-1024-raspi) with a RPI4 and I have the exact same issue as you with ethtool not showing support and ptp4l.service not found.
Did you manage to find a workaround?
According to the readme (https://github.com/twteamware/raspberrypi-ptp#enable-software-timestamping-in-ptp4l-configuration) it should be enough to enable software support.