[mythtv] DVB channel flipping hang

[Tom Hughes]

In message <1124924091.13428.127.camel at thesis.kristjansson.com>
          Daniel Kristjansson <danielk at cuymedia.net> wrote:

> On Wed, 2005-08-24 at 23:14 +0100, Mark Weaver wrote:
>
> > The backend hangs if I repeatedly flip channels with the latest SVN
> > code, mythbackend -v siparser,channel,record and gdb backtrace are at:
> 
> It appears that the FE_SET_FRONTEND ioctl is non-blocking and we are
> treating it as if it is blocking... this appears to be an old problem..

This is the infamous blank recordings bug - if you look back in the
archives you'll various posts where I reached the same conclusion.

I've been running 0.18.1 with a patch that uses FE_READ_STATUS to
wait for tuning to complete rather than FE_GET_EVENT because the
kernel source looked like that would block properly but I still
loose recording sometimes.

In 0.18.1 what happens is that the the FE_SET_FRONTEND call is
made and Myth then decides tuning is complete and starts looking
for the PMT and one arrives from the old multiplex before tuning
is actually complete and because the requested service is missing
Myth ignores the PMT and reports a PMT timeout rather than waiting
for another PMT from the new multiplex.

Tom

-- 
Tom Hughes (tom at compton.nu)
http://www.compton.nu/