[linux-dvb] [PATCH] Garbage diseqc messages emitted by bt8xx/dst module

Yeasah Pell yeasah at schwide.com
Fri Jun 9 16:56:28 CEST 2006

Gnome42 Gnome42 wrote:

> Hi Yeasah, I tried this patch to improve tuning with a twinhan 1020A
> with diseqc.
> I had to disable this bit of code in order for it to work at all.
> Without this code disabled, it sounded like the card never got power,
> or possibly it turned the power on and off really quickly?
>> +       /* apparently the actual voltage is set in the tuner command. 
>> ugh. */
>> +       if (need_cmd) {
>> +               dst_set_polarization(state);
>> +               dst_write_tuna(fe);
>> +       }
Sorry, yeah -- I didn't realize anybody was using that patch. That part 
was actually an attempt to resolve another issue with the card, but it 
didn't work very well as you discovered. The problem is that the dst 
can't actually change voltage between 18V and 13V without issuing a 
tuning command (it can only turn the voltage off or back to whatever the 
last tuning command set it at), but the software I'm working on wants to 
be able to control the voltage without actually tuning.

So I put an extra tuning command in there to try to get the voltage 
switch to happen immediately, but the dst bridge really doesn't like it 
when you send multiple tuning requests in rapid succession, which is 
what happens in the normal case -- i.e. the software sets the voltage 
and shortly thereafter issues a tuning request.

You should definitely leave in the set_polarization line though (just 
take out the write_tuna), or alternatively I have an updated patch with 
some more stuff fixed if you're interested.

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