Fix for ppstest timeout

[fitzy89]

With a recent update to Raspbian, it's necessary to add arm_64bit=0 to /boot/config.txt and reboot in order to get the pps working

[domschl]

I am using PPS with arm_64bit=1 but with Manjaro. So there's probably something else going on? Maybe the access rights for /dev/pps0 changed? Do you have some more information (e.g. dmesg logs?)

[fitzy89]

I was following your guide using the latest Raspbian on a Pi 4B and at the point of running ppstest I was seeing timeout errors, the same issue as mentioned in this post - raspberrypi/linux#5430 which is what led me to the above solution which seems to work fine for me.

[domschl]

Interesting! A kernel bug seems to be the cause: a patch intended for 32bit got wrongly applied to 64bit. Did you try the fix suggested in:

raspberrypi/linux#5430 (comment)

namely:

sudo rpi-update pulls/5478

which pulls a new 64bit kernel patch? (so arm_64bit=1 for the patched kernel).

Edit:

A simple sudo rpi-update should probably do the trick too, my guess is that the fix to the i2c-bcm2835 that was required is now awailable via standard kernel updates.

Note however that kernel updates are not recommended for normal use, since there's always the probability that something else breaks.

[OdessaEyes]

For me it didn't work.
Rpi3b, 5.15.76-v7+ #1597 SMP armv7l GNU/Linux, Raspbian GNU/Linux 11 (bullseye)
sudo rpi-update or/and add arm_64bit=0 to /boot/config.txt didn't solve the problem.

If you have any other ideas I'd be happy to try.

Linux rpi3b 6.1.45-v8+ #1671 same situation.

[domschl]

@OdessaEyes : You might be encountering a different problem, since you are running 32bit Raspbian.
If your error is not timeouts on ppstest with messages like:

time_pps_fetch() error -1 (Connection timed out)

then it might be best to open a separate bug report describing what you tried?

[Nebulosa-Cat]

after using sudo rpi-update update to Linux Pi-Server 6.1.61-v8+ #1696 SMP PREEMPT Thu Nov 2 16:44:46 GMT 2023 aarch64
still got time_pps_fetch() error -1 (Connection timed out)
maybe only sudo rpi-update pulls/5478 will work?

[Nebulosa-Cat]

and looks sudo rpi-update pulls/5478 not work

[domschl]

The issue seems to be fixed with current (2023-12) bookworm release of Raspberry Pi OS. No more patches are needed. Please re-check, and let me know if there are still issues.

[romm32]

Hello. I am running the Raspberry OS, I downloaded the current version (2023-12, 32-bit version) and then ran raspi-update. I am now running an updated version from Jan 22 of 2024. I followed all the instructions with a fresh install of the OS (before starting to run the suggested commands, I ran an apt update then apt upgrade), until I got the connection timeout error in the ppstest. I added the arm64bit line to /boot/config.txt, then rebooted, and nothing happened. I also tried with the raspi-update (as previously mentioned), and a reboot, and it is still not working. I am quite new to Raspberry Pis and don't know if there is something I am doing wrong, or if the issue is a bug in the OS, but I would appreciate any help available.
Thanks in advance

[domschl]

@romm32 : Non of the fixes should be necessary anymore. Which model of Raspberry Pi are you using?
Please paste the ppstest command together with it's output into the bug-report.
E.g. for me it looks like:

sudo ppstest /dev/pps0
trying PPS source "/dev/pps0"
found PPS source "/dev/pps0"
ok, found 1 source(s), now start fetching data...
source 0 - assert 1706619523.000001477, sequence: 1233465 - clear  0.000000000, sequence: 0
source 0 - assert 1706619524.000001080, sequence: 1233466 - clear  0.000000000, sequence: 0

I should update the instructions once we figure out what happened with your installation.

[domschl]

I just checked: there is still ongoing work on this bug here Raspberry kernel pps issue 5430 .
One thing (if you have one of the newer models) you can try is to use Raspberry OS 64bit?

[romm32]

I am using a Raspberry 4 Model B. I was first using it with Ubuntu 22, then switched to Raspberry OS and tried both for 32bit then for 64bit (versions from December 2023, following what was mentioned here). I tried the arm64bit change and it didn't work, nor did a raspi-update. The output was similar to yours, except I was getting the following line right after the "ok, found 1 source(s)...".

time_pps_fetch() error -1 (Connection timed out)

Given I am following this guide for my undergraduate final project, and this was one of many things left on my to-do list, I kept trying with different settings yesterday. I eventually switched to Raspberry OS for 64bit, an archive version from September 2022, and everything worked just fine (no need to try any fixes). I know it is not exactly a solution, but I guess this should be enough for the project I am working on. I was able to get chrony working, but I don't see the PPS as one of the sources. My GPS antenna is kind of bad, and I was working indoors, so I am planning on testing everything when I have a decent amount of GPS satellites available (about 10), and hopefully I will see the PPS as one of the sources.

Thank you for your quick answer, I will continue following these issues just in case someone finds another fix I could try in the future.

[aGGreSSiv]

Hello,
It's an interesting problem. The NTP server is currently installed in 3 different models, pi3, pi4 and pi5. Pi4 and pi5 have the same operating system. The versions are the same. both are 64bit. (I'm not sure if it is independent of the operating system, the kernal versions are the same) However, while pi3 and pi4 work without any problems, I am experiencing this problem on pi5. I tried every suggestion I found here and online. none of them helped. As I mentioned in my previous questions, I am not very good at Linux. If everything is the same, what's left? If you find a solution or see an update released that will solve this problem, can you write it here?

[Nebulosa-Cat]

after I'm fully manuly upgrade to PiOS lite Bookworm (follow this guide: https://gist.github.com/jauderho/6b7d42030e264a135450ecc0ba521bd8)

and i delete the bcm2708.pps_gpio_pin=4 at /boot/firmware/cmdline.txt
(the cmdline.txt and config.txt looks move to /boot/firmware at bookworm)

now it work normally

[domschl]

Thank you @Nebulosa-Cat for this information! I will update the guide.