On 03/11/2006 01:10 PM, Hans Verkuil wrote:

>On Saturday 11 March 2006 18:44, Chris Schanzle wrote:
>  
>
>>Cut to the chase:
>>
>>Mar 11 11:58:31 localhost kernel: ivtv0 warning: ENC: (0) DMA Error
>>0x0000000b
>>Mar 11 12:01:03 localhost kernel: ivtv0 warning: ENC: (0) DMA Error
>>0x0000000b
>>Mar 11 12:01:37 localhost last message repeated 5 times
>>Mar 11 12:02:19 localhost last message repeated 3 times
>>Mar 11 12:03:40 localhost kernel: ivtv0 warning: ENC: (0) DMA Error
>>0x0000000b
>>Mar 11 12:03:54 localhost kernel: ivtv0 warning: ENC: (0) DMA Error
>>0x0000000b
>>Mar 11 12:04:25 localhost kernel: ivtv0 warning: ENC: REG_DMAXFER 2
>>wait failed
>>Mar 11 12:04:29 localhost kernel: ivtv0 warning: ENC: DMA still
>>Pending while stopping capture!
>>
>>Sir Hans, have you or will you in the near future have a chance to
>>look into the causes of the above DMA errors?  These errors cause
>>corrupt video and audio from the point when the message starts until
>>the system is rebooted (rmmod/modprobe ivtv doesn't help).
>>    
>>
>
>Don't count on it. It has always been my intention to look into this 
>when I start a cleanup of that code, but that has been delayed. It is 
>also surprisingly rare: only on one card do I occasionally get this 
>error. The PVR350 that I actually use for my recordings (as opposed to 
>driver development) never encountered this error.
>
>It is likely that the cause of the problem is somewhere in 
>dma_from_device() in ivtv-irq.c: I suspect that some value is not reset 
>or a buffer not flushed in case of a DMA error. The DMA error itself is 
>not the cause, that just triggers a retry.
>
>How well can you reproduce it? If you get it often then I could give you 
>patches to apply and test.
>
>Regards,
>
>       Sir Hans  :-)
>  
>

Yay!  My problem is *VERY* reproducable - within tens of minutes.  My
system is basically unusable (generates unwatchable recordings) with DMA
enabled on the PVR-250.  Willing to test any patches.  Thanks in advance!


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