hdmi audio stops at 10 minutes after boot --- always.

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1

I have hdmi audio working up until 10 minutes from boot time. Exactly 10 minutes…every boot.

I test with ‘speaker-test’. Running continuously. Output stops exactly at TimeBoot + 10mins.

There is no outward appearance of a problem:

  1. The output of speaker-test is not affected. Blissfully continues to test: “Right channel…Left channel…Right channel…etc”.
  2. No message in dmesg.
  3. No message in /var/log/*

How can I debug?

Any hypotheses?

Thanks

root@beaglebone:~# uname -a
Linux beaglebone 4.4.30-ti-r64 #1 SMP Fri Nov 4 21:23:33 UTC 2016 armv7l GNU/Linux

root@beaglebone:~# cat /etc/debian_version
8.6

2

Do you have a serial debug cable ?
I have seen posts here saying that some messages only get spit out on
that port.

3

I’d probably try to run your executable through strace, and output into a file.

4

No. I don’t have a serial debug cable.

If you have a link to the other messages, can you provide a reference (a link or search string or something) so I can read them too?

What exactly do you mean /that some messages only get spit out on that port’? I don’t know what action to take from this.

Can you elaborate?

Thanks.

5

What do you think strace would show?

I used strace a long time ago. Back then, it traced the system calls of an application process. What should I look for in that output?

Thanks,
John

6

Ok so then you know what strace is then I suppose. In your case, I would
*imagine* strace would make things really easy to understand what is
happening at that 10 minute mark. Since in your shoes, I'd run everything
normally, but through strace. There is very likely going to be a lot of
output. So you'd want to output that to a file, using the -o option( dash
oh, as in Oscar ). Passed that I then( I would think ) becomes a matter of
reading the file in reverse, until you find a potential culprit. That is:
start of the end of the output file reading towards the beginning.

Quite honestly, I have no idea what you should be looking for, But I
suspect you'll know it when you see it. But if you do not, You could paste
the last 10 lines of output here, or so. Then see if any one else here can
spot a potential problem. I think that it could be very likely you will not
see an exact cause, but instead see something that should give a very good
indication as to what the problem is.

7

One thing that does come to mind is that having just recently removed the kernel module from loading at boot on my own system here. Is that it could be related to DMA. As it seems the sound modules do include a dma sound module. Which, there has been some issues with DMA on this platform in the past. I only remember seeing issues with dma in relation to SPI, but perhaps it’s also an issue for sound too ? Pure speculation on my behalf.

8

William,

Thanks.

If your suggestion is that the speaker-test program itself is silencing the hdmi output with some driver call…I’m really doubtful. I hope you don’t mind me saying so. For a couple of reasons, but mainly: The audio stops 10 minutes after boot time even if there is no audio process running at the time. For example, I can run speaker-test before 10min mark to prove audio comes out right after boot. Then turn off speaker-test before the 10min mark, and run it after. There is no audio.

Do I understand you correctly? That is, strace speaker-test?

…or maybe I should strace another process that maybe disabling sound. Guessing which one is the root question anyway.

John

9

$ strace -o /path/file speaker-test

It’ll at least tell you where it stops, and most likely why.

10

More to the point. Try running the command I gave above AFTER the audio already stops. That’ll at least tell you where, and why it fails. After that you can investigate these reason why. Perhaps providing a fruitful google search, or at minimum giving you something to report.

11

Ok, my bad, I completely missed the part where you said it still output, just no sound from speakers . . .

Well then, that will be problematic to troubleshoot.

With that said, which kernel version are you running ? Ok, 4.4.30-ti-r64

Have you tried different kernels ? newer, and older.

12

So this is not guaranteed to work, but worth exploring. Give the following a shot:
$ sudo alsa force-reload

But if that does not work. Try running:

$ sudo apt-get update

$ sudo apt-get install --fix-missing

$ sudo alsa force-reload

$ sudo reboot

I’ve seen mention of this multiple times, but always for Ubuntu it seems. So maybe it’ll cure your problems, maybe it won’t.