From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mx1.redhat.com ([209.132.183.28]:55954 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932534Ab2EVUlq (ORCPT ); Tue, 22 May 2012 16:41:46 -0400 Message-ID: <4FBBFAF8.8080203@redhat.com> Date: Tue, 22 May 2012 22:45:44 +0200 From: Hans de Goede MIME-Version: 1.0 To: =?ISO-8859-1?Q?R=E9mi_Denis-Courmont?= CC: Antti Palosaari , Linux Media Mailing List , Hans Verkuil , Ondrej Zary Subject: Re: RFC: V4L2 API and radio devices with multiple tuners References: <4FB7E489.10803@redhat.com> <4FB7E827.7070701@iki.fi> <201205221926.38970.remi@remlab.net> In-Reply-To: <201205221926.38970.remi@remlab.net> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-media-owner@vger.kernel.org List-ID: Hi, On 05/22/2012 06:26 PM, Rémi Denis-Courmont wrote: > Le samedi 19 mai 2012 21:36:23 Antti Palosaari, vous avez écrit : >> On 19.05.2012 21:20, Hans de Goede wrote: >>> Currently the V4L2 API does not allow for radio devices with more then 1 >>> tuner, >>> which is a bit of a historical oversight, since many radio devices have 2 >>> tuners/demodulators 1 for FM and one for AM. Trying to model this as 1 >>> tuner >>> really does not work well, as they have 2 completely separate frequency >>> bands >>> they handle, as well as different properties (the FM part usually is >>> stereo capable, the AM part is not). >>> >>> It is important to realize here that usually the AM/FM tuners are part >>> of 1 chip, and often have only 1 frequency register which is used in >>> both AM/FM modes. IOW it more or less is one tuner, but with 2 modes, >>> and from a V4L2 API pov these modes are best modeled as 2 tuners. >>> This is at least true for the radio-cadet card and the tea575x, >>> which are the only 2 AM capable radio devices we currently know about. >> >> For DVB API we changed just opposite direction - from multi-frontend to >> single-frontend. I think one device per one standard is good choice. > > If I understand Hans correctly, he suggests to use two tuners on a *single* > radio device node, much like a single video device nodes can have multiple > video inputs. So I think you agree with Hans, and so do I. Correct, although the plan has changed in the mean time to model the 1 tuner as 1 tuner, and extend the v4l2 tuner API to deal with a tuner which can tune multiple bands. Which seems the best way forward :) Regards, Hans