[mythtv] an update on SVN firewire recordings

Steven Adeff adeffs.mythtv at gmail.com
Sun Jun 24 22:33:14 UTC 2007

On 6/24/07, Daniel Kristjansson <danielk at cuymedia.net> wrote:
> On Sat, 2007-06-23 at 17:10 -0400, Steven Adeff wrote:
> > On 6/23/07, Jim Westfall <jwestfall at surrealistic.net> wrote:
> > > Steven Adeff <adeffs.mythtv at gmail.com> wrote [06.23.07]:
> > > > I've finally finished my move and got my mythtv backend up and running
> > > > again. I've got two DCT6200 boxes daisy chained to one firewire port
> > > > on my motherboard.
> > > >
> > > > A while back Daniel mentioned commenting a  line out to do a bus
> > > > reset, which I've done. The problem is I still see some recordings not
> > > > working after a bus reset. If I happen to be around and paying
> > > > attention I can run firewire_tester -B, sometimes a few times, to get
> > > > it to work, but the firewire recording code doesn't seem to have the
> > > > same ability?
> > >
> > > You dont want to have the reset code enabled if you have 2+ STBs.  It
> > > resets all devices on the firewire bus, which while fixing one STB it
> > > will cause the other to break.  You can end up with 2 recorder threads
> > > fighting trying to fix their STB, but in doing so breaking the other.
> >
> > well, there should to be a way to get the firewire_tester "fix" code
> > into the backend then or one tuner can just sit there not outputting
> > anything and the backend does nothing but wait for it to start
> > streaming data, which it won't.
> The code in MythTV that you enabled does basically what
> firewire_tester does. The reason it is disabled by default

then why does running firewire_tester on its own when the problem
occurs fix the problem?

> is because Linux drivers don't like it if there is another
> bus master on the bus that tries to do bandwidth allocation,
> so we end up having to do multiple bus resets to actually
> reset the bus. With one bandwidth allocating device on
> the bus we need two resets. I don't know how many we need
> with 2,3,4,etc.

sometimes the bus reset works, sometimes not. when it doesn't and I'm
around to catch it, running firewire_tester manually gets it working.

> I no longer have a FireWire STB so I'm not likely to be
> improving this. If you have one firewire recorder you
> can enable the automatic resets, but if you have more
> than one firewire recorder on the same bus YMMV.
> The Linux drivers may improve, one of the firewire guys is
> writing a completely new driver from scratch that will do
> bandwidth allocation. But this may take several years and
> he's only planning to support the newest firewire chips.

and by then i feel none of it will matter, i figure they'll lock
everything down by then so firewire capture is no longer possible =(


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