[linux-dvb] Re: Budget DVB-C tuning problems; dirty solution

[Antti Kaihola <antti.kaihola@linux-aktivaattori.org>]

on 2004-02-07 at 12:57, I wrote:
> > The rule seems to be:
> > If I wait for more than 8 seconds after a successful tuning, the
> tuning will fail.
> > An immediate re-tuning attempt after a failed or successful tuning
> will succeed.


OK, here's a dirty modification which makes the no-lock problem go away.
This is from someone who doesn't understand shit about the driver and
has never seen any hardware specifications, but was just poking around
in the dark... :)  I just hope it helps others figure out what the real
problem is.


In dvb_frontend.c function dvb_frontend_set_parameters(), add an extra
call and a delay before the dvb_frontend_internal_ioctl call:

dvb_frontend_internal_ioctl (frontend, FE_SET_FRONTEND, param); /* wake
up! */
dvb_delay(100); /* clear your head before action */
err = dvb_frontend_internal_ioctl (frontend, FE_SET_FRONTEND, param);


Somehow the extra ioctl call wakes the card up and properly prepares it
for the real action. I'm kind of simulating the
two-tunings-in-a-row-succeed phenomenon I've encountered before.

With this ugly fix dvbtune now works correctly, i.e. tunes successfully
also after a longer pause than 8 seconds.

I haven't experimented too much with the delay in between, I just
noticed that if I remove it, I still get some no-locks.




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