[linux-dvb] Re: [Patch] Adding support for the Hauppage HVR1100

Mauro Carvalho Chehab mchehab at brturbo.com.br
Wed Nov 30 19:01:23 CET 2005


Em Ter, 2005-11-29 às 09:47 -0500, Steve Toth escreveu:
> Johannes Stezenbach wrote:
> > On Mon, Nov 28, 2005, Steve Toth wrote:

> 3) A totally different, longer term approach. (My actual preference). 
> Have a single tuner.ko module which deals with ALL plls and tuning 
> requirements (analog/digital). Have demods (and/or cx88) call a 
> registratation mechansim "tuner_register_pll" with a number of callbacks 
> and capabilities. This would require a lot of rework on all of the 
> demods but nicely bring tuning back into a single place. tuner.ko would 
> then be a dependency on dvb_core (?) and cx88xx (or possibly even a 
> newer v4l_core / v4l2_compat?).
	IMHO, this is a good approach, and not so difficult to handle. In fact,
from V4L side, we have two tuner handlers (both currently merged at
tuner.ko):
	tuner-core.c - generic functions, capable of handling any kind of
tuners. It handles V4L ioctls and passes, via callback, to specific
tuners;
	tuner-simple.c - for "simple tuners" that have:
- cut-off freqs/switch control byte
- a generic way to configure the device:

	div= freq + Video IF + offset

	(freq is, in fact, freq / 62500; Video IF maybe also Radio IF, for
radio mode)

	4 values to be passed to tuner (div MSB, div LSB, config switch,
generic control byte)

	Specific tests for a few tuners.

	This about the same as dvb-pll.c does:

        div = (freq + desc->entries[i].offset) /
desc->entries[i].stepsize;
        buf[0] = div >> 8;
        buf[1] = div & 0xff;
        buf[2] = desc->entries[i].cb1;
        buf[3] = desc->entries[i].cb2;


	Also:

	1) most (all?) dvb plls are also at V4L;
	2) tuner struct at V4L2 API have a reserved value that means it is
Digital TV. There are also some control functions to enable/disable 
tuner mode (from radio <--> TV) that can be extended to include also
Digital TV. This way, tuner can do proper enabling/disabling
analog/digital modes on hybrid cards.

	So, for me, it seems that would be easy to integrate both codes into
one. 

> Steve
> 
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Cheers, 
Mauro.




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