[linux-dvb] Re: [RFC] multi std silicon tuners and analog tuners

Manu Abraham abraham.manu at gmail.com
Mon Apr 9 19:02:21 CEST 2007


Manu Abraham wrote:
> Hi All,
> 
> Currently, we have silicon tuners loading FIR filter specific DSP boot
> codes for tuners as well, of course Silicon tuners. While working with
> the STB6100 silicon tuner which had been a rogue for that matter, found
> that the same could be extended for tuners as well.
> 
> Some tuners as what i see, loads delivery system specific firmware to
> optimize the FIR filter characteristics on the teeny DSP of the silicon
> tuner. In some cases the DSP boot code is as well included in the
> firmware which needs a reset of the DSP, but in many cases doesn't need so
> 
> The approach can be used for *all* hybrid tuners how complex it might be
> since it leaves room for future expansion as well.
> 
> My thoughts go like this.
> 
> currently the existing infrastructure is assumed to be thus ...
> 
> DVB API is modified with the multiproto API update which thus has the
> enhanced Silicon tuner changes already for the STB6100.
> 
> with regards to the DVB API , the userspace sets a delivery system for
> the demodulator, which can be a cached parameter at the bridge(ie, the
> card config to be precise, which is also known as the glue logic)
> 
> so when subsystem A acquires control, a lock is acquired by the bridge
> (the bridge can be imagined as a fulcrum for switching between systems)
> This locking would be a FSM for handling different switches.
> 
> now the bridge can acquire/release locks, needs some code additions to
> the bridge to have this, for old devices it doesn't matter at all.
> 
> now when subsystem B request control, it makes a request to the control
> manager on the bridge, the control is passed all the way down from the
> frontend(DVB)/ tuner(V4L) so it still remains quite independent the
> tuner/frontend part from the bridge
> 

[..]

> with regards to TUNER (V4L) the same can be achieved using set standard
> or similar.
> Will have additionally one more callback (a new one)
> 

A possible implementation patch i have attached to this post. The base
tree is at http://jusst.de/manu/stb0899-v4l-dvb.tar.bz2

The bridge specific locking code also i have included in the tuner
driver. In reality it should go all the way down to the bridge driver.
The driver doesn't actually do any real read/writes, but just provides
the placeholders for the same. All delivery systems(DVB)/standards(V4L)
are used in it. In real life one wouldn't have so many standards and
delivery systems (for illustrational purposes)


Awaiting comments

Manu

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