From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail.kapsi.fi ([217.30.184.167]:46036 "EHLO mail.kapsi.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751602Ab3LMT1Y (ORCPT ); Fri, 13 Dec 2013 14:27:24 -0500 Message-ID: <52AB5F99.7070405@iki.fi> Date: Fri, 13 Dec 2013 21:27:21 +0200 From: Antti Palosaari MIME-Version: 1.0 To: Hans Verkuil CC: linux-media@vger.kernel.org, Mauro Carvalho Chehab Subject: Re: [PATCH RFC 4/4] v4l: 1 Hz resolution flag for tuners References: <1386806043-5331-1-git-send-email-crope@iki.fi> <1386806043-5331-5-git-send-email-crope@iki.fi> <52A96C00.8060607@xs4all.nl> <52A9F0C7.2050602@iki.fi> <52AB1447.9090601@xs4all.nl> <52AB2B02.3090300@iki.fi> <52AB30E9.40209@xs4all.nl> In-Reply-To: <52AB30E9.40209@xs4all.nl> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: On 13.12.2013 18:08, Hans Verkuil wrote: > On 12/13/2013 04:42 PM, Antti Palosaari wrote: >> On 13.12.2013 16:05, Hans Verkuil wrote: >>> On 12/12/2013 06:22 PM, Antti Palosaari wrote: >> I really appreciate that as simply has no enough knowledge from V4L2 API >> and API changes are needed. I will try to list here shortly some SDR >> devices in general level enough. >> >> ant = antenna >> host = host computer, PC (SW modulator/demodulator) >> ADC = analog to digital converter >> DAC = digital to analog converter >> amp = amplifier >> mixer = "TX tuner" >> >> receiver: >> ant <> RF tuner <> ADC <> bridge <> host >> ant <>ADC <> bridge <> host >> ant <> up-converter <> RF tuner <> ADC <> bridge <> host >> >> transmitter: >> ant <> amp <> mixer <> DAC <> bridge <> host >> ant <> mixer <> DAC <> bridge <> host >> ant <> DAC <> bridge <> host >> >> Those are the used building blocks in some general view. ADC (DAC) is >> most important hardware block, but RF tuner is also critical in practice. >> >> So what I understood, V4L2 API "tuner" is kinda logical entity that >> represent single radio device, containing RF tuner, demodulator and so. >> That same logical entity in DVB API side is frontend, which is mostly >> implemented by demodulator with a help of RF tuner. >> >> So what is needed is to make V4L2 API entity (tuner I guess) that could >> represent both ADC and RF tuner. > > Well, a V4L2 tuner represents the hardware that requires a frequency. > Which for typical radio and TV devices means the RF tuner + demodulator > combo. So externally you see only one tuner, but internally there are > often two devices (tuner and modulator) that have to be controlled. > > For SDR you have an RF Tuner with a frequency and an ADC with a frequency, > and the two frequencies can be set independently. So representing that > as two tuners seems like a sensible mapping to me. Correct. Both RF tuner and ADC are independent each others and both must be possible to adjust runtime. Shortly, all-in-all, I will implement those as a tuner#0 is ADC and tuner#1 is RF tuner. Patches with corrections follow soon. regards Antti -- http://palosaari.fi/