From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail.kapsi.fi ([217.30.184.167]:60246 "EHLO mail.kapsi.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757232Ab2ESSg1 (ORCPT ); Sat, 19 May 2012 14:36:27 -0400 Message-ID: <4FB7E827.7070701@iki.fi> Date: Sat, 19 May 2012 21:36:23 +0300 From: Antti Palosaari MIME-Version: 1.0 To: Hans de Goede CC: Linux Media Mailing List , Hans Verkuil , Ondrej Zary Subject: Re: RFC: V4L2 API and radio devices with multiple tuners References: <4FB7E489.10803@redhat.com> In-Reply-To: <4FB7E489.10803@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: 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. From DVB FE change there is now some problems as a frequency limits and other parameters are shared between all the standards... For example cxd2820r demod, which is DVB-T/T2/C, says it supports even DVB-C2 as 2nd generation flag is derived from the DVB-T2. regards Antti -- http://palosaari.fi/