Re: [PATCH 08/10] dvb_frontend: create a new ops to help returning signals in dB

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> add a new ops that will allow tuners to better report the
> dB level of its AGC logic to the demod drivers. As the maximum
> gain may vary from tuner to tuner, we'll be reversing the
> logic here: instead of reporting the gain, let's report the
> attenuation. This way, converting from it to the legacy DVBv3
> way is trivial. It is also easy to adjust the level of
> the received signal to dBm, as it is just a matter of adding
> an offset at the demod and/or at the bridge driver.

Mauro,

Have you verified this work with a detailed spectrum analysis study?
If so then please share. For example, by measuring the I/F out of
various tuners in a mix of use cases, with and without the AGC being
driven by any downstream demodulator? Also, taking into consideration
any external LNA variance.

I'm concerned that a tuner AGC Gain is a meaningless measurement and
in practice demodulators don't actually care, and tuners don't
implement their gain reporting capabilities correctly at all.

This feels like a solution to a problem that doesn't exist.

-- 
Steven Toth - Kernel Labs
http://www.kernellabs.com
+1.646.355.8490
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