[mythtv-users] Firewire Issues

[Bruce Markey]

DISAFAN wrote:
> I confess, I am suffering from a lack of understanding of how to proceed 
> on my firewire issues. Positively, all of the analog channels...the 
> basic cable stuff...seems to come through on my SA3250HD. The HD 
> channels seem to come through. The digital versions of the analog feed 
> aren't tuning...but I figure if I can get rid of the PVR-150 hooked into 
> the box output, it will allow me to free up a PCI slot for another QAM 
> tuner.
> 
> That said, my firewire recording, like many peoples, is inconsistent. 
> When it records, it records. When it doesn't, it doesn't, and I have to 
> stop MythTV, reset the firewire bus, and that seems to clear the problem.
> 
> I have high hopes a future bugfix will stabilize the connection...it 

Wed, 18 Jul 2007 is actually in the past. If you are using a 64
bit kernel, there is a bug that causes a memory error which make
recording and firewire_tester appear to fail due to a connection
problem. However, it is a kernel memory error and the connection
is actually okay. "grep dma_region_alloc /var/log/syslog".

: root at bigboy \# ; zcat /var/log/syslog.4.gz | grep dma_region_alloc
Oct  3 21:54:54 bigboy kernel:  [<ffffffff880652c7>] :ieee1394:dma_region_alloc+0x37/0x126
Oct  3 21:54:54 bigboy kernel: dma_region_alloc: vmalloc_32() failed
Oct  3 21:54:56 bigboy kernel:  [<ffffffff880652c7>] :ieee1394:dma_region_alloc+0x37/0x126
...

I had to go back in my logs to find these as they haven't happened
since I applied this patch the evening of Oct 3:

http://lkml.org/lkml/2007/7/18/34

Since booting the patched kernel, I have never had one firewire
recording fail. I need to run "firewire_tester -p -n 0 -R" once
after rebooting then the connection stays good until the next
reboot (the memory bug would make firewire_tester give a false
negative but most likely the connection was always good).

...
> I have searched through the archives and seem no closer to a best 
> solution, so I decided to seek commentary.

You missed the dev list thread "LFireDev Error: Starting A/V
streaming: Cannot allocate memory". I'm lining up my ducks
to submit a complete and proper bug report for kernel.org so
this can be fixed without patching in future kernels.

--  bjm