[linux-dvb] Re: Another issue: frontend timeout value and low symbol rates

[Johannes Stezenbach <js@convergence.de>]

Andrew de Quincey wrote:
> 
> > In the meantime, I've found another problem in dvb_frontend.c:
> >
> > Although the code has the ability to scan about on frequencies surrounding
> > the requested frequency, it isn't actually being given the time to do so.
> > The following patch fixes this, and ensures at least one cycle of scanning
> > completes before giving up. The reason I haven't checked this in is because
> > I'm worried it breaks something else, and I want to give anyone time to
> > object.
> 
> Actually on second thoughts that big initial delay on the first tune seems to 
> be about 3 seconds.... and the initial value of delay in the frontend_thread 
> IS 3*HZ... 
> 
> In that case, the first attempt to tune if it needed a zigzag scan would fail 
> because the initial delay is so huge. Then the next attempt would work, as 
> long as the thread hadn't died too fast. 
> 
> Sound familiar anyone?

IMHO the sane thing to do would be:
- FE_SET_FRONTEND sets some flag meaning "were are changing channels"
  and then wakes up the frontend thread
- FE thread then reinitializes "delay" to some sane initial value

The schedule_timeout(1) in FE_SET_FRONTEND is just bogus.

But the whole update_delay() thing is the result of many
experiments done by Holger, and works fine most of the time...

I would be happy if you could clean this up.

Johannes


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