[alsa-devel] Invalid PCM pointer with CMI8738 and pcm.c buffer underuns
Continued from here: http://article.gmane.org/gmane.linux.alsa.devel/121575
http://www.alsa-project.org/main/index.php/XRUN_Debug
# Enable basic debugging and dump stack, check hardware pointer on the period update # Usefull to just see, if PCM stream is stopped for a reason (usually wrong audio process timing from scheduler) # And to check the values from driver
echo 11 > /proc/asound/card0/pcm0p/xrun_debug
Okay, I not compiled my own kernel with CONFIG_SND_PCM_XRUN_DEBUG, CONFIG_SND_VERBOSE_PROCFS, CONFIG_SND_DEBUG all enabled in the kernel configuration, I have an xrun_debug file, but it doesn't seem to list anything, then I also tried with cat instead of echo, and just a 0 showed up:
___________________________________________________________________ $ echo 11 > /proc/asound/card0/pcm0p/xrun_debug bash: /proc/asound/card0/pcm0p/xrun_debug: Permission denied
# echo 11 > /proc/asound/card0/pcm0p/xrun_debug bash: /proc/asound/card0/pcm0p/xrun_debug: Permission denied
$ cat /proc/asound/card0/pcm0p/xrun_debug 0 ___________________________________________________________________
Continued from here:
http://article.gmane.org/gmane.linux.alsa.devel/121575
http://www.alsa-project.org/main/index.php/XRUN_Debug
# Enable basic debugging and dump stack, check hardware pointer on the period update # Usefull to just see, if PCM stream is stopped for a reason (usually
wrong
audio process timing from scheduler) # And to check the values from driver
echo 11 > /proc/asound/card0/pcm0p/xrun_debug
Okay, I not compiled my own kernel with CONFIG_SND_PCM_XRUN_DEBUG, CONFIG_SND_VERBOSE_PROCFS, CONFIG_SND_DEBUG all enabled in the kernel configuration, I have an xrun_debug file, but it doesn't seem to list anything, then I also tried with cat instead of echo, and just a 0 showed
up:
$ echo 11 > /proc/asound/card0/pcm0p/xrun_debug bash: /proc/asound/card0/pcm0p/xrun_debug: Permission denied
# echo 11 > /proc/asound/card0/pcm0p/xrun_debug bash: /proc/asound/card0/pcm0p/xrun_debug: Permission denied
$ cat /proc/asound/card0/pcm0p/xrun_debug 0
You need root privilege to debug
sudo echo 11 > /proc/asound/card0/pcm0p/xrun_debug
Check the system log , you should find the hwptr change at 10ms interval if vlc use period time of 10ms
Try different period time/size to verify that the hardware really support any arbitrary period time/size requested by the application ?
You need root privilege to debug
sudo echo 11 > /proc/asound/card0/pcm0p/xrun_debug
___________________________________________________________ $ sudo echo 11 > /proc/asound/card0/pcm0p/xrun_debug ___________________________________________________________
implies: ___________________________________________________________ # echo 11 > /proc/asound/card0/pcm0p/xrun_debug ___________________________________________________________
So I did have root priviledges when I executed that command, and it still gives me a Permission denied error.
I tried the command under root and it accepted the command but didn't print anything after issuing the command. So I guess it worked?
Check the system log , you should find the hwptr change at 10ms interval if vlc use period time of 10ms
Again, what system log? Be a little bit more specific please.
Try different period time/size to verify that the hardware really support any arbitrary period time/size requested by the application ?
VLC doesn't have any options or terminal parameters to be able to change the period as you mention.
Okay, nevermind, the OS froze as I've tried to change the level on the PCM channel, so I rebooted and tried to look for anything that might have left a trace for what has happened, and I think I found what you were looking for: http://pastebin.com/YfP61KBk
It was under /var/log/messages.0 (same things also under /var/log/syslog for some weird reason) I haven't been able to see what caused the freezing.
Also found this, not sure if it's useful: _______________________________________________________________________ Apr 12 23:30:50 flying-topsoil kernel: [18087.771787] [<c12b3777>] ? dump_stack+0xa/0x13 Apr 12 23:30:50 flying-topsoil kernel: [18087.771813] [<f819d839>] ? xrun+0x9a/0xb2 [snd_pcm] Apr 12 23:30:50 flying-topsoil kernel: [18087.771824] [<c104e65d>] ? ktime_get_ts+0x30/0x77 Apr 12 23:30:50 flying-topsoil kernel: [18087.771838] [<f819e43c>] ? snd_pcm_update_hw_ptr0+0x91/0x744 [snd_pcm] Apr 12 23:30:50 flying-topsoil kernel: [18087.771847] [<c103bca3>] ? hrtimer_start_range_ns+0x20/0x25 Apr 12 23:30:50 flying-topsoil kernel: [18087.771853] [<c103b9c2>] ? hrtimer_try_to_cancel+0x4a/0x51 Apr 12 23:30:50 flying-topsoil kernel: [18087.771864] [<f8198cbb>] ? snd_pcm_hwsync+0x30/0x46 [snd_pcm] Apr 12 23:30:50 flying-topsoil kernel: [18087.771874] [<f819ab7b>] ? snd_pcm_common_ioctl1+0x5c/0xa0f [snd_pcm] _______________________________________________________________________
participants (2)
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andoru -
Raymond Yau