[mythtv-users] Random DMA errors

[John Drescher]

On 11/19/06, Peter Carlsson <maillist.peter at home.se> wrote:
>
> Hello!
>
> I have recently observed random DMA errors. Since I haven't had
> this problem before I haven't taken notice when there was a
> discussion about DMA errors on this list. Now I have checked
> the earlier posts but it does not seems to be the exact same
> problem.
>
> I have not done any deep investigation but I thought I would
> share some observations with the list.
>
> In /var/log/syslog I sometimes get the following message when
> recording a program:
>
> Nov 18 22:44:11 htpc kernel: ivtv0 warning: ENC: (0) DMA Error 0x0000000b
> Nov 18 22:44:42 htpc last message repeated 9 times
> Nov 18 22:45:43 htpc last message repeated 37 times
> Nov 18 22:46:01 htpc last message repeated 13 times
> Nov 18 22:46:04 htpc kernel: ivtv0 warning: ENC: REG_DMAXFER 2 wait failed
> Nov 18 22:46:08 htpc kernel: ivtv0 warning: ENC: DMA still Pending while
> stopping
> capture!
>
> The problem is that it seems like it only happens when mythfrontend
> is running. Any suggestions appreciatad.
>
> /Peter
>
> htpc:~# uname -a
> Linux htpc 2.6.16-2-k7 #1 Fri Aug 18 19:48:42 UTC 2006 i686 GNU/Linux
>
> htpc:~# dpkg -l *ivtv*
> Desired=Unknown/Install/Remove/Purge/Hold
> | Status=Not/Installed/Config-files/Unpacked/Failed-config/Half-installed
> |/ Err?=(none)/Hold/Reinst-required/X=both-problems (Status,Err:
> uppercase=bad)||/
> Name           Version        Description
>
> +++-==============-==============-============================================
> ii  ivtv-firmware  1.8.22037      firmware for use with the ivtv kernel
> driver
> ii  ivtv0.6-module 0.6.3-1+2.6.16 ivtv Linux kernel module (0.6 branch)
> ii  ivtv0.6-source 0.6.3-1        source for ivtv drivers (0.6 branch)
> ii  ivtv0.6-utils  0.6.3-1        utilities for use with the ivtv kernel
> drive
> ii  libvideo-ivtv- 0.13-3         Perl extension for using V4l2 in the
> ivtv pe
> htpc:~#
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>

This is a known problem with ivtv and some hardware and cpu powersaving.
Check the ivtv user list for some help and a selection of workarounds.
http://ivtvdriver.org/index.php/Mailinglists

Is this error causing video or audio artifacts? Can you easily upgrade your
kernel to 2.6.18 and ivtv to 0.8?

John
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