[mythtv] Ticket #1945: DVB-S/diseqc patch

Christer Roth christer at roth.cc
Wed Jul 26 13:41:28 UTC 2006

Yeasah Pell wrote:

>Mark Buechler wrote:
>>Yeasah, I did notice a few times today something odd with your switch 
>>code. The very first switch command sent (as the backend starts) 
>>doesn't seem to work on either on my switches, or doesn't always work, 
>>anyway. I'm wondering if your diseqc reset is throwing the switch for 
>>a loop for a brief period. What's the wait time between switch 
>>commands? Is this reset necessary? Tomorrow I'll test by taking out 
>>the reset to see if that helps though this problem doesn't happen all 
>>the time for me.
>>- Mark.
>The reset is there just to get everything into an initialized state -- 
>it only does it when the frontend device is first opened, as you say. It 
>isn't strictly required, since all the devices should be explicitly 
>reset to their desired values anyway, it's just in there to make sure 
>everything is completely sane before proceeding.
>DiSEqCDevTree::ResetDiseqc is where the reset is done, you can look 
>there for details on what exactly happens at reset time. Basically the 
>reset delays are 100ms, and by default currently it power cycles the 
>diseqc devices as well. It would be interesting to know if the situation 
>improved if you disabled the power cycle (change it to call ResetDiseqc 
>with a the hard_reset parameter set to false).
>Does this happen on more than one kind of DVB card, or have you only 
>noticed it on one type so far? I think you have a couple of twinhan dst 
>cards in your setup, don't you? I have a couple of patches outstanding 
>for that driver, one of which has been accepted but doesn't yet seem to 
>be in the main hg tree yet. One of them improves tone/power control, but 
>more importantly the other one improves error reporting. Without that 
>patch,  failed commands would often not be reported to the application 
>(and in my experience there are times when the driver won't successfully 
>complete commands for extended periods of time, 100s of ms -- hence the 
>relatively lengthy ioctl retry sequences in the diseqc code.) I could 
>easily see that being part of the problem...

I would very much like to try out your patches for the dvb-s twinhan dst 
card. I am running SVN 10628 and a week old mercurial v4l-hg, but still 
have problems when changing a channel to another when these reside on 
different multiplexes, as I quite frequently experience the cards are 
not able to get a lock. I am running 8 cards connected to a multiswitch 
controlling 4 quattro lnbs. Also, will increasing the dvb_tuning_delay 
(currently at 0) in the capturecard table help me at all for these 
cards? Appreciate your help on this.


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